Functional Neurology, Rehabilitation and Ergonomics

Functional Neurology, Rehabilitation and Ergonomics Volume 2 Number 3 Table of Contents Editorial Guilty by Explanation Gerry Leisman

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Scientific Papers Appropriate Usage, Training Requirements and Public Safety Issues Pertaining to Needle EMG and Electrodiagnostics Joel B. Brock and Albert Comey The Use of Computerized Dynamic Posturography in the Functional Neurology Practice Frederick R. Carrick, Susan E. Esposito, James L. Duffy, Derek Barton, and Diana M. Stephens Restoring of Brain Entropy and Complexity after Rehabilitation of Traumatic Brain Injury Nazareth P. Castellanos, Elisa Rodríguez-Toscano, Javier García-Pacios, Pilar Garcés, Nuria Paúl, Pablo Cuesta, Ricardo Bajo, Juan García-Prieto, Francisco del-Pozo, and Fernando Maestú Intersensory Integration in Functional Neurology: An Engineer's Perspective of Music as an Interventionary Medium Farah Jubran and Gerry Leisman

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Nutritional and Dietary Considerations for Basal Ganglia Disorders Datis Kharrazian

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Postural Disturbances Associated with Whiplash Injuries to the Cervical Spine Adam Klotzek and Frederick R. Carrick

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The Brain on Art: Auditory, Visual, Spatial Aesthetic, and Artistic Training Facilitates Brain Plasticity Gerry Leisman

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Connectivity Cognition and Psychosis in the Physical Brain Avi Peled

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Intestinal and Blood-Brain Barrier: Interface between Health and Diseases Aristo Vojdani and Joel Bautista

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Poster Abstracts 3rd Annual Conference of the International Association of Functional Neurology and Rehabilitation - Abstracts from the Conference IAFNR News and Events Tricia Merlin

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Literature Calling: A Review of Recent Publications of Interest to Functional Neurology

New York

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Journal of

Functional Neurology, Rehabilitation, and Ergonomics The Official Journal of the International Association of Functional Neurology and Rehabilitation The aim of this interdisciplinary journal is to provide a forum for the fields of Biomedical and Rehabilitation Engineering, Neuropsychology, Clinical Neurology, Human Factors and Ergonomics, and vocational assessment and training to present critical ideas, theories, proofof-concept for technology solutions, and data-based evaluative research to facilitate return to work or more effective functional development in children and adults. FNRE is published quarterly by Nova Science Publishers, Inc. 400 Oser Avenue, Suite 1600 Hauppauge, New York 11788, USA Phone: (631) 231-7269 Fax: (631) 231-8175 E-mail: [email protected] Web: www.novapublishers.com ISSN: 2156-941X Institutional Subscription Rates per Volume (2012) Print: $295

Electronic: $295

Combined Print and Electronic: $442

Additional color graphics might be available in the e-version of this journal. Copyright © 2012 by Nova Science Publishers, Inc. All rights reserved. Printed in the United States of America. No part of this Journal may be reproduced, stored in a retrieval system, or transmitted in any form or by any means: electronic, electrostatic, magnetic, tape, mechanical, photocopying, recording, or otherwise without permission from the Publisher. The Publisher assumes no responsibility for any statements of fact or opinion expressed in the published papers.

Editor-In-Chief Gerry Leisman Garden City, NY USA Jerusalem, Israel Co-Editor-In-Chief Robert Melillo Garden City, NY USA Assistant Editor Production Janet Groschel Gilbert, AZ USA

Assistant Editor Production Alicia M. Zelsdorf Charlotte, NC USA

Assistant Editor News and Events Tricia Merlin Cape Canaveral, FL USA

Sergio Azzolino San Francisco, CA USA

Editorial Board Members Newton Howard Cambridge, MA USA

Jackie Oldham Manchester, UK

Randy Beck Perth, Australia

Megan L. Hudson West Springfield, MA USA

Chandler Phillips Dayton, OH USA

Paul Berger-Gross Bayside, NY USA

Efraim Jaul Jerusalem, Israel

Anthony L. Rosner Boston, MA USA

Eti Ben-Simon Tel-Aviv, Israel

Datis Kharrazian Carlspoor, CA USA

Peter Scire Peachtree City, GA USA

John A. Brabyn San Francisco, CA USA

Samuel Landsberger Los Angeles, CA USA

Fredric Schiffer Boston, MA USA

Lynn M. Carlson West Springfield, MA USA

Calixto Machado Havana, Cuba

Suryakumar Shah Pomona, NJ USA

Ted Carrick Cape Canaveral, FL USA

Joy MacDermid Hamilton, Ontario Canada

Emmanuel Donchin Tampa, FL USA

Joav Merrick Jerusalem, Israel

Maria E. Stalias Manhasset, NY USA, Athens, Greece Joseph Weisberg Great Neck, NY USA

Andrew L. Egel College Park, MD USA

Raed Mualem Nazareth, Israel

Leslie Weiser Boston, MA USA

Khosrow Eghtesadi West Palm Beach, FL USA

Paul Noone Hampton E. Victoria, Australia

Seung Won Lee Seoul, Korea

Barbara Hicks Kingsford, MI USA

Editorial

Funct Neurol Rehabil Ergon 2012;2(3):pp. 159-160

ISSN: 2156-941X © 2012 Nova Science Publishers, Inc.

Guilty by Explanation Gerry Leisman Editor-in-Chief FNRE Scientific Director F. R. Carrick Institute for Clinical Ergonomics, Rehabilitation, and Applied Neuroscience-USA The National Institute for Brain and Rehabilitation Sciences, Nazareth Academic Institute, Nazareth, Israel

Have you ever gotten a traffic ticket and noticed on the back of the form that there is a box that you can tic off for “not guilty,” “guilty,” or “guilty with an explanation?” The first two are simple to explain, simply pay the fine or go to court and pay the fine. The “guilty with an explanation” is fundamentally more interesting. When we feel insecure in what we know and in who we are, I think that we have an overwhelming tendency and need to explain. When we go before the traffic court judge to explain why it is that we committed this “horrible crime” we may get a reduced fine, but for sure, we are going to pay. For some strange reason we have an overwhelming need to explain phenomena. The reason that we exist is because there was “Big Bang” and that plus the principles of evolution, coupled with Newtonian and Einsteinian physics allows us to explain phenomena. Now that we have explained a particular phenomenon, we apparently feel more secure in our relationship with the universe and perhaps G-d or his absence, no mind whether Einsteinian and Newtonian physics works or not. Unfortunately, Newtonian physics does not explain why gravitational force is proportional to inertial mass, that gravitational force violates special relativity, and that there exists a fundamental error in Newtonian thought in the Perihelion shift of Mercury (43 sec arc per century). With reference to Einsteinian physics, his concept of the universe was static and closed (i.e. has hyperspherical topology and positive spatial curvature), and

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Gerry Leisman

contains uniform dust and a positive cosmological constant with value precisely , where G is Newtonian gravitational constant, ρ is the energy density of the matter in the universe and is the speed of light. The radius of the curvature of space of the Einstein universe is equal to:

Because the universe is now known to be expanding, the Einstein universe is no longer regarded as a viable model for our universe. Moreover, it is unstable in the sense that any change in the value of the cosmological constant, the matter density, or the spatial curvature will result in a universe that either expands and accelerates forever or re-collapses to a big crunch. So, both Newton and Einstein explanations have major problems in explaining the nature of things. Now that we have gone through this little exercise in explaining, do we feel any more content in our understanding the nature of life? I would venture to say that we would, those of us who are not physicists. Physicists, however, would be perturbed and that perturbation would prompt more and better science. So what is the function of science then? Simply stated, it is the examination of relationships. Any explanation whatsoever is not science but rather “hand waving.” Science does not deal with cause – only with relationship. That is why we can talk about “Big Bang” but cannot talk about pre “Big Bang” – cause is the subject of Religion and Philosophy. So, why on earth is it necessary to talk about such concepts as “GABA challenge” and “leaky brains” or even “leaky guts.” The GABA Challenge Test is claimed to be important because it can help identify a

leaky blood-brain barrier (BBB). If the Blood-Brain-Barrier is intact, the claim is that one will not feel an effect from the GABA - GABA itself should not be able to cross the brain’s protective barrier. If one does feel a change, then there is a requirement that one will need to repair both leaky gut and the leaky blood-brain barrier. My question is very simple, where on earth is the evidence for such a statement? One can say that a substance is administered and a particular change is noted, one can remove that substance and an individual returns to baseline condition, but one has no confidence in making causal statements. These statements are not-scientific within the context of the above definition of science and serve only to allegedly placate individuals and entities whom you think require those explanations. DO NOT EXPLAIN ANYTHING! Deal with clinical outcome only! A-B-A is the name of the game. Problem-relevant treatment-pull relevant treatment-see if problem returns. Period! You cannot explain and if you do, you become “Guilty by Explanation.”

Scientific Papers



Appropriate Usage, Training Requirements and Public Safety Issues Pertaining to Needle EMG and Electrodiagnostics Joel B. Brock1,2 and Albert Comey1 Carrick Institute for Graduate Studies, Cape Canaveral, FL 32920, USA ²FR Carrick Institute for Clinical Ergonomics, Rehabilitation and Applied Neurosciences, Garden City, NY 11530, USA



Correspondence: Dr. Joel Brock, Carrick Institute for Graduate Studies, Cape Canaveral, FL. 32920 Email: [email protected]

Abstract Electrodiagnostic studies, including nerve conduction velocity testing, needle electromyography and evoked potential studies, are a vital part of healthcare. This is especially true in the genre of neurology, soft tissue injuries, and determining the extent of various types of injury. In addition, electrodiagnostics offer imperative information that aids in accurately determining the area of injury, extent of injury, and important factors that relate to an appropriate diagnosis, prognosis, and issues related to patient recovery and predicted outcomes of various treatments When performed properly, invaluable details about an injury can be provided to a wide variety of requesting providers, from the surgeon needing to know whether a case is surgical in nature, to the provider attempting to prescribe medication, to the conservative practitioner who is determining if conservative care is the appropriate course of action. In order to keep this perspective clear, it is important to understand the history and groups utilizing this type of diagnostic testing and then discuss training necessary to provide valid studies, as well as discuss public safety issues.

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Joel B. Brock and Albert Comey

Keywords: Electrodiagnosis, Nerve conduction velocity, electromyography, evoked potentials, Electrodiagnosis

Introduction The history of electrodiagnostic testing goes back some time, in particular, to the days when electromyography (EMG) was being performed in the early 1970s at the Mayo Clinic and the equipment was rudimentary. EMG was coined by Weddell et. al. in the early 1940s [1]. At that time the machines were based on vacuum tube technology, were large and cumbersome, took up most of the room, and had to be tweaked and calibrated and heavily filtered. Filters had to be set manually for each patient as well as for each test. Heating lamps, for adequate room temperature, were not necessary because the heat alone from these machines in a small room was enough to keep patients warm and make the neophyte trainee perspire, especially when the instructor entered the room [2].

Equipment Technology has advanced and companies have designed machines which have greatly decreased the machine size. The equipment and software available has become very efficient in capturing and manipulating testing data into a form that is more usable to the clinician. This greater portability and greater ease of gathering data due to software development has allowed a greater interest in performing such studies. There are several components related to electrodiagnostic equipment to become familiar with in order to keep up with the evolution of hardware and software. First there is the base unit, which is the brain of

the testing equipment. I supplies the power and coordiantes all of the devises attached to it that are used to perform the different forms of testing. Next there is the amplifier. This is used to plug the lead, ground, and active cables into. A stimulator is used to generate a small electrical current to administer to the patient evoking a response to be recorded in NCSs (nerve conduction studies) as well as various EPs (evoked potential studies) [3]. Electrodes are used to record the potentials and may be in the form of a tab or needle. The equipment has evolved since the inception of testing. It is more durable, has better filtering systems and has more advanced software which ultimately allows for more rapid waveform generation, data crunching and calculations. It makes data more diagnostic and allows technicians and providers alike the chance to see more patients, be more accurate when testing and have data that is more reproducible. It is anticipated that both the hardware and the software components of EDX testing will continue to evolve in the future and appropriate education should be offered to allow better usage and utilization of evolving technology. Appropriate education and implementation of technological change is estimated to significantly reduce technical artifact and user error when testing is performed. Currently all programs that adequately teach and instruct electromyography and electrodiagnosis should include concepts related to electricity, machine hardware, advancements in analytical software and ways to generate more usable data. This is a key component of patient and public safety.

Appropriate Usage, Training Requirements and Public Safety Issues …

Electromyography (EMGs) Electrodiagnostic testing is comprised of several different types of testing. EMG was the first electrodiagnostic test to be developed and utilized for determining pathology. This procedure involves the placement of a needle into various muscles to record different stages of muscle activity, including muscle at rest, minimal contraction, and maximal activity. At rest, normal muscle is electrically silent. Damaged muscle tissue may result in spontaneous depolarization of individual or groups of muscle fibers. This abnormal activity can be detected during the needle examination portion of the electrodiagnostic examination [4,5]. Determining the presence of spontaneous depolarization in the form of altered insertion activity, fibrillation

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potentials, positive sharp waves, fasciculations, complex repetitive discharge (CRD), myotonia, myokymia, neuromyotonia, and cramping is imperative and can suggest a destructive or actively denervating process [5]. End plate spikes and end plate noise at times can also be present during EMG testing. These potentials do not typically suggest an actively denervating process. It is imperative when testing that the electromyographer avoid confusion when determining the presence of end plate potentials verses other spontaneous potentials which could suggest active denervation. Lacking the ability to differentiate these potential types can easily generate misdiagnosis, unnecessary surgical procedures and inappropriate medical treatment.

Figure 1. Motor unit and related areas that various pathologies and potentials might manifest.

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The needle EMG is designed to determine if there is active denervation potentials that are present in a given muscle group or determine if there has been any form of reinnervation as a result of a previously actively denervating process based on the model exemplified in Figure 1. The extent of damage can be determined with needle EMG as well as pathology that might translate clinically into a neuropathic, myopathy, a peripheral process or even a central process. This makes needle EMG a very valuable tool to the clinician that is trying to determine the extent of injury, the type of treatment that might be necessary and the prognosis of recovery that can be expected [1,2,4,5].

Nerve Conduction Studies (NCSs) Nerve conduction studies (NCSs) are an important part of the complete electrodiagnostic exam. Various nerve condition studies exist, including motor, autonomic and sensory NCV testing as well as blink and repetitive nerve stimulation. In an NCS examination, an electrical charge is delivered to a peripheral nerve via stimulation. That charge is carried down the nerve and generates a muscle contraction [6]. A recording electrode is placed on a muscle innervated by that nerve, and information about the impulse can be recorded, including its latency (the time needed for the impulse to travel from stimulus to recording). The nerve conduction velocity can also be calculated to determine the travel speed of various short segments of peripheral nerve (distance between two stimulation sites/time difference in latencies). Latency prolongation and conduction delays can be suggestive of complex peripheral nerve damage, in particular myelin pathology.

Amplitude of generated waveforms on nerve conduction studies can also be evaluated for morphological change or loss in negative or total area. These measurements are considered a sensitive indicator of peripheral nerve damage, in particular the axonal component. The needle electromyographic along with the nerve conduction study work together diagnostically to determine the location of a lesion, the fiber type involved, various components of a nerve that might be damaged, whether there is active denervation or any form of reinnervation, patterns of pathology, extent of injury and valuable data that aids the practitioner with patient prognosis and necessary treatment measures [7].

Evoked Potentials (EPs) Evoked potentials (EPs) are electrical signals generated by the nervous system in response to sensory stimuli. EP testing is the application of electrodiagnostic testing to the central nervous system (CNS) with limited diagnostic application related to the PNS as well.

Eps Are a Clinically Useful Means to Do the Following 



 

Demonstrate abnormal sensory function when the neurologic examination results do not reveal abnormalities. Reveal clinically unsuspected pathology when demyelinating diseases are suggested. Determine the anatomic distribution of a disease process. Objectively monitor a patient's progress or deterioration over time.


Varieties of EP Testing Includes     

Somatosensory EPs (SSEPs) Visual EPs (VEPs) Brainstem auditory EPs (BAEPs) Dermatomal EPs Myotomal EPs

Recording electrodes may be either surface electrodes or small subdermal needles placed anywhere along the neuropathway, including the spine and scalp [7]. Evoked potential studies are more useful when looking at pathways of the central nervous system and at times proximal portions of the PNS. EMG and NCS studies are more useful at evaluating the PNS. At times, the combination of EPs, NCVs and EMGs is the only way to get a complete clinical picture. These tests are an extension of a comprehensive subjective patient intake and physical examination. At times the outcomes of the aforementioned EDX studies has to be corroborated with other labs and imaging services.

Somatosensory Evoked Potentials (SSEPs) SSEP studies are the most widely used form of EP test testing. Stimulation occurs at the extremity and recordings are made on the scalp, near the sensory cortex and at various other levels including the cervical spine and at times over Erb’s point or the plexus region. This technique may be used to locate the level of the injury in the nerve root, spinal cord or brain. In CNS insults, such as spinal cord trauma and stroke, SSEP testing has been helpful in establishing the degree of insult and in determining its prognosis, especially when imaging does not give an accurate explanation of clinical presentation. EPs can at times give a

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physiological explanation whereas imaging only gives an anatomical description of a given pathological process. SSEPs can also be used to localize demyelinating diseases, such as multiple sclerosis, and root level injuries in cervical and lumbar radiculopathies, especially those related to the dorsal root region as opposed to the ventral root region which is more easily evaluated by the needle EMG. In addition, they can be used to aid in determining the level of coma and to evaluate for brain death. SSEPs are also useful for intraoperative monitoring of patients undergoing various neurosurgical procedures. This type of monitoring reduces the chance that a surgeon is damaging or compromising neurological tissue during a surgical procedure. The real time feedback during intraoperative monitoring can be invaluable.

Visual Evoked Potentials (VEPs) Brainstem Auditory Evoked Potentials (BAEPs) In VEP testing, the practitioner uses a photoelectric or checkerboard-pattern flash to stimulate the optic nerve. This pattern is then recorded on the cortex, arriving at the occiput, near the visual centers. Injuries along the optic nerve, including demyelination or compression, can result in a delay of the latency and loss of the amplitude of the signal, similar to the results in NCVs. In cases of multiple sclerosis, for example, abnormalities in the VEP are often the first indicator of the disease process. Optic chiasm tumors also produce recordings suggesting abnormalities. Visual acuity may be determined in infants with suspected visual disturbances. Brainstem auditory evoked responses are used to evaluate the integrity of auditory pathways. The can help determine pathology

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and evaluate for various types of neurological compromise in the auditory system. EP studies are a great diagnostic tool. The difficulty with evoked studies is that they must be done in a room or area that has very little environmental or electrical disturbance so that waveform distortion does not occur. There is also a lot of technical skill involved when performing them. It is very easy to generate studies that are nothing but artifact. This creates a scenario of escalating healthcare cost for studies that offer no diagnostic benefit and can lead to misdiagnosis and unnecessary procedures. Evoked studies must be used to evaluate the right conditions, by trained individuals in a fashion that generates good data and billed appropriately when performed.

The American Board of Electrodiagnostic Specialties (ABES) It is important that the field of electrodiagnosis be regulated and standards established so that the individuals practicing in the field do so in a safe and educated fashion. Monitoring educational programs available for learners, updating educational standards, educating other stakeholders and offering feedback about the electrodiagnostic profession to its members is necessary for public safety. The American Board of Electrodiagnostic Specialties (ABES) is a multidisciplinary board that is a sub-agency of the American College of Functional Neurology and is the credentialing authority for electrodiagnosis for the American Chiropractic Neurology Board (ACNB) of the American Chiropractic Association’s Council on Neurology. The ACNB is accredited by the National Commission for Certifying Agencies (NCCA) and is recognized by the American Chiropractic Association (ACA) as the sole authority for

credentialing in neurology for the chiropractic profession. The ABES awards the FABES - Fellow of the American Board of Electrodiagnostic Specialties, to those who complete the required training and pass the examinations as outlined by the ABES. The purpose of the Electrodiagnostic certification programs of the ABES is to conduct certification activities in a manner that upholds standards for competent practice in the health care specialty of Electrodiagnostics as a subspecialty of Functional Neurology. The Board also conducts recertification designed to enhance the continued competence of the individual [8]. Certification standards and training requirements in neurological subspecialties are under constant review by the ACNB who directed the ABES to establish the minimum training required to perform electrodiagnostic testing at a competent level, while also protecting the public from injury or misdiagnosis. The ABES mandates that clinicians obtain a minimum of 250 academic credit hours in Electrodiagnosis from an accredited Institution in association with clinical training and experience [9]. The ABES addressed a need for a solid foundation in the related anatomy and differential diagnosis, so that the clinician knows what testing to perform, where to perform that testing, and how to perform the testing in a real time manner. This knowledge base must be in place so that the clinician can then apply the technical skills to the didactic portion of the training. It is of the upmost importance that competent technical skills be applied to the principles of electrodiagnostic testing. This technical training does not only involve mastering the techniques of clean workspace, proper handling of the needle, proper handling of the stimulator, but maintaining patient comfort and safety as well. These technical skills need to be

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Appropriate Usage, Training Requirements and Public Safety Issues … developed and used in conjunction with the learned base of knowledge, as electrodiagnostic testing should be performed and modified while it is being administered, rather than running a generic set of tests and interpreting the results later. Each patient is an individual, has a different health history, a separate differential diagnosis, and unique electrodiagnostic findings. It would not be appropriate to administer the same NCV, EMG or evoked potential tests to every patient as this would not be an ethical performance or utilization of testing provided. Not to mention that the appropriate diagnosis may not be reached, which is the desired result of the testing in the first place. The primary challenge in offering a training program to meet these standards is to make sure that the learners would have ample time for hands-on training and practical portions so that a sufficient didactic foundation is established. Ensuring that the learners are well versed in diagnosis, differential diagnosis, outcome assessment as well as necessary treatment measures has also been a goal of the ABES. It is important that anyone doing EDX studies be sound pertaining to technique, performance, interpretation, recommendations, report writing, billing and ethics. The ABES has made it a point to mandate that any program seeking accreditation offer well rounded programs so that competent specialists be educated and certified. There are not many reference programs available that might assist in the creation of a training program in Electrodiagnosis. The only set of standards available is that of the American Association of Neuromuscular and Electrodiagnostic Medicine [10]. They have a variety of position statements that make recommendations, but they do not approve individual training programs. The AANEM recommends a six-month residency training program in which 200

complete EDX performed [11].

evaluations

must

be

The Current Requirements from the ABES Include the Following 

300 Needle Insertions (EMG) which are to be monitored, supervised and recorded in a log.  100 Nerve Stimulations (NCV) that must be monitored, supervised, and recorded in a log.  Five (5) Upper SSEP studies.  Five (5) Lower SSEP studies.  Three (3) BAEP studies.  Three (3) VEP studies.  Hundreds of sample cases are evaluated and report writing is mandatory.  The learner must demonstrate that the or she can perform an entire study before completing any program with no technical error.  The practicum and testing for certification looks at technical, professional and diagnostic skills along with patient safety, ethics and medical necessity. ABES standards emphasize not only the technical components of the NCV and EMG, but other important and relevant topics as well. Electrodiagnostic training must include a thorough instruction in anatomy of the peripheral nervous system and central nervous system, and their relationship to the nerves and muscles being tested in the practice of electrodiagnostics. Clinicians must also be trained in the proper evaluation and examination of the neurologic and musculoskeletal systems and demonstrate competency in developing an appropriate differential diagnosis and eventual diagnosis. This may include disorders of the nerves, muscles, neuromuscular junction, central nervous system, as well as genetic, inherited,

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acquired, nutritional, toxic, infectious, autoimmune, vasculitic and ventral horn cell pathology [11-23]. Training programs must address various diagnostic imaging and diagnostic laboratory testing central to neurological practice [23]. Report writing and how to provide the referring provider with not only a diagnosis, but relevant recommendations based on the findings is emphasized. Finally, testing should be ordered and provided only when medically necessary, with proper utilization, and in an ethical manner. It is the position of the ABES that clinicians who complete this required training and subsequently pass both a written and a practical examination will possess the skills and training necessary to provide appropriate, ethical, and safe electrodiagnostic testing. In addition, yearly continuing education in Electrodiagnosis would be required in order to maintain the Certification or Fellowship.

Public Safety Issues The issues pertaining to public safety and electrodiagnosis are not without significant controversy in the field. In various states and geographical regions, there has been much debate about scope of practice and who is qualified to offer such studies. The debate has ranged from whether using a needle is incisive, invasive, surgical, beveled or conical. There has also been the inclusion of diagnostic competency or ability to render a diagnosis in a clinical setting. The ABES has determined that there are many factors that are relevant on the topic of public safety, including but not limited to damage that can be inflicted from usage of a needle, risk of infection, shock injury and most importantly, misdiagnosis due to poor skill or ability. Other issues that

are of more concern to the ABES are performing practitioners lacking knowledge pertaining to the detail of peripheral and central neurological anatomy, neuromuscular physiology, pathophy siology, principles of electricity, technical and testing considerations, physical examination skills, laboratory and blood chemistry evaluation knowledge as well as differential diagnosis pertaining to not just the neuromuscular and neurological arena, but other diseases that could impact testing and outcomes as well. The ABES feels that it is important to briefly discuss these issues in light of public safety issues. The usage of a needle for the purpose of rendering a diagnosis does not go without the possibility of consequence, needle EMG not being excluded. The most obvious concern is that of infection, anatomic damage and pneumothorax; however, other problems can at times be a factor. The two greatest concerns being hematoma and compartment syndrome during needle EMG performance, especially in high-risk muscle groups and anticoagulated patients. Mandatory education standards implemented by the ABES suggest that any educational program accredited offer information regarding medications and certain disease processes that might pose a greater risk for uncontrolled bleeding and hematoma formation during needle testing. Learners should be able to factor and consider such risks in each patient. Various studies suggest that patient usage of anticoagulant therapy combined with high-risk muscle groups have little correlation with subclinical or clinical hematoma formation, especially when INR is therapeutic [24]. Available literature suggests that when clinical correlation is considered, the usage of needle EMG is relatively safe with anticoagulated patients and less problematic than possible complications that might arise with the

Appropriate Usage, Training Requirements and Public Safety Issues … removal of anticoagulant therapy for the purpose of EMG testing. This suggests that the usage of a needle for the purpose of diagnostic EMG is safe in the vast majority of patients on anticoagulants, especially when appropriate technique is used [25]. Diseases that create uncontrolled bleeding should be considered as a standard in all patients outside of realm of anticoagulant therapy. All curriculums must iterate the components of sanitary testing conditions as well as clean and at times sterile techniques. The risk of infection or contamination during testing can be minimalized significantly and the public can be safe when various standards are taught to and met by EDX practitioners. The greatest concern regarding EDX testing outside of immediate danger to that of the patient during the procedure is misdiagnosis. Electromyography seemed to be the most concerning. Misdiagnosis in the form of not being able to discern the difference between end plate potentials and active denervation was particularly of concern. Poor muscle identification, the inability to understand innervation, nerve root involvement and proper muscle activation has also been a concern. It is also noted upon observation of multiple disciplines that perform electromyography that many do not even perform motor unit analysis and few understand or accurately perform and analyze recruitment and or activation. This renders EDX as more dangerous not from the point of view of infection, hematoma or injury from the needle, but rather from the stand point of misdiagnosis due technical difficulty and totally irrelevant and inaccurate data gathering. It is clear that poor data gathering can create scenarios in which unnecessary surgery or other forms of care are suggested or performed. The ABES sees this as the greatest danger and concern

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surrounding the topic of needle EMG and it does not feel that concerns related to EDX can be limited to the usage of a needle. These issues and problems are clearly not limited to chiropractors, physical therapists or general practitioners, but medical neurologists as well as physiatrists. Nerve conduction studies have traditionally been discussed as safer, less invasive, and its practice of gathering data, more acceptable by technicians and nondoctoral trained practitioners. The ABES sees this as a flawed view and stance Technicians must be skilled in anatomy, physiology and have the skill to determine clinical presentation as a study is performed so that the longitudinal level of the lesion can be further assessed in a real time situation. At times a clinician may need to add further studies outside of a typically performed battery of tests to get an accurate representation or sampling in order to render an accurate diagnosis or list of differentials. An example would be the addition of nonstandard axillary, suprascapular or musculocutaneous nerves in order to get a better evaluation of the brachial plexus or additional nerves to further assess a possible polyneuropathic process. Regardless of the condition, in depth differential diagnostics skills as well as physical examination abilities is necessary to do an appropriate NCS and much of the medical profession has underestimated this in order to create an avenue to substantiate that technicians can do these, so that they do not have to expend the time or the energy to do such studies. The ABES sees this as a problem, especially when anatomical variants are present or difficult body types are tested. The delegation of any form of EDX testing, whether with a needle, or done superficially is not suggested by the ABES. The history, intake, physical examination, NCS, EP or needle EMG study all coalesce into a big

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picture that must be done accurately at each interval in order to get a reliable diagnostic picture. Delegating any of these portions to technicians or someone not trained in any or all of the aforementioned steps can lead to misdiagnosis or unreliable diagnostic data. The physical examination is a clear concern pertaining to EDX testing. The market is expanding and more studies and responsibility related to EDX are being delegated to under-qualified technicians and health care providers, many of which do not even do a physical examination. Many of those that do a physical, lack the skill or ability to interpret any of the findings that might be gathered from the physical examination. A basic yet concerning example is the ever growing observation that many providers doing studies do not the know the difference between upper or lower motor neuron disease, proximal verses distal peripheral nerve damage, primary muscle verses neuromuscular junction pathology or various patterns pertaining to poly neuropathy. Any electrodiagnostic study is an extension of concepts that are created and generated by the physical examination. If that examination is not done, performed by under qualified practitioners or if that examination generates erroneous information, then the trajectory of the entire EDX study can be skewed, mislead or inaccurate. The ABES has noted that regardless of degree or educational background, this a problem across the spectrum of those providing EDX services. All educational programs that submit a curriculum to the ABES must demonstrate that the art and performance of the physical examination is addressed in conjunction with EDX specific technique and related differential diagnostic ability. Detailed knowledge related to regions being tested and understanding how to properly code for those services is essential [26]. Testing should be billed in an ethical

manner. Without adequate training and knowledge of anatomy there may be confusion on how many or the type of units billed during any given battery of tests or procedures. Proper training and education is necessary when understanding the true definition of generated CPT codes, and what services are entailed in fulfilling that code. When training and detailed understanding of anatomy and physiology is absent or lacking it can lead to inadvertent, unethical or inappropriate billing and collections procedures. This is a danger to the public because this practice leads to higher healthcare costs which can ultimately lead to stricter and limited access of diagnostic services to deserving patients. The knowledge of when to perform electrodiagnostic studies is important to the overall discussion. A properly performed test without medical necessity is not only unethical, but could be construed as malpractice or even fraud. Knowing what signs and symptoms and examination findings are present provides the basis as to whether or not electrodiagnostic should be performed. Many times a delegated technician does not have the ability to clinically discern the difference in testing that is or is not medically necessary. Electrodiagnostic testing is an extension of the patient history and physical examination. Regardless of the source of the referral, medical necessity must be established before any testing is initiated and the provider performing the testing has the obligation to determine need. Once medical necessity has been verified, then the patient can be further evaluated diagnostically to determine the diagnosis and course of care based on those findings.


Conclusion Electrodiagnostic studies must be done when clinically necessary and appropriate. Practitioners must be aware of the potential of over-utilization for any purpose, including inappropriate monetary gain as well as issues related to under-utilization, especially when lower motor pathology or active denervation might be present. A thorough and competent knowledge of clinical necessity in concert with technical ability is promoted by accredited programs of education and clinical experience at the level mandated by the ABES. The Council on Neurology of the American Chiropractic Association maintains that practitioners who obtain data in the form of an electrodiagnostic study or anyone who formulates an opinion or reads any form of generated data must also have accredited training in anatomy, physiology and pathology, and be skilled in differential diagnosis. Technical safety must be considered for those who perform studies. This includes detailed understanding of anatomy as well as common pitfalls in all arenas of electrodiagnosis. The training necessary to perform electrodiagnostic studies in a safe fashion and in a manner that ensures public safety is promoted by appropriate training and board certification in the discipline.

[3]

[4]

[5]

[6]

[7]

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[12]

[13]

[14]

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Jones LK. Nerve Conduction Studies: Basic Concepts and Patterns of Abnormalities. Neurol. Clin. 2012;30:405-427. Rubin DI. Needle Electromyography: Basic Concepts and Patterns of Abnormalities. Neurol. Clin. 2012;30:429-456. Preston DC, Shapiro BE. Needle electromyography Fundamentals, normal and abnormal patterns. Neurol. Clin. 2002;20:361–396. Wilbourn, A. Nerve conduction studies Types, components, abnormalities, and value in localization, Neurol. Clin. 2002;20:305338. Agranoff, AB, Andary MT, Moberg-Wolff, EA, Rosenberg, JN, Talavera, F. Electrodiagnosis. Retrieved from http://emedicine.medscape.com/article/3070 96-overview, 2011. www.acfnsite.org.http://www.acfnsite.org/su bspecialtycertification.php?pg=4#3 Brock B, Comey A, Fedor D, Brodkin R, Cook C, Hoxie, S. (2012, February 15, 2012). ABES Position Paper [Electronic mailing list message]. Retrieved from www.acfnsite.org AANEM Website. (n.d.). http://www. aanem.org/Practice/Position-Statements.aspx American Association of Electrodiagnostic Medicine Educational Guidelines for Electrodiagnostic Training Programs. (1997). Retrieved from http://www.aanem.org/ getmedia/470fb367-ee3b-473b-85752af659695691/ed_gl_for_edx_tp.PDF.aspx Chad DA. Electrodiagnostic approach to the patient with suspected motor neuron disease. Neurol. Clin. N. Am. 2002;20: 527–555. Herrmann DN, Logigian, EL. Electrodiagnostic approach to the patient with suspected mononeuropathy of the upper extremity. Neurol. Clin. 2002;20:451–478. Katirji, B, Kaminski HJ. Electrodiagnostic approach to the patient with suspected neuromuscular junction disorder. Neurol. Clin. 2002;20:557–586. Klein CJ. The Inherited Neuropathies. Neurol. Clin. 2007;25:173–207. Kumar N. Nutritional Neuropathies. Neurol. Clin. 2007;25:209–255. Lacomis D. Electrodiagnostic approach to the patient with suspected myopathy. Neurol. Clin. 2002;20:587–603.

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Received: June 17 2012 Revised: June 27 2012 Accepted: June 28 2012



The Use of Computerized Dynamic Posturography in the Functional Neurology Practice Frederick R. Carrick1,2,3 , Susan E. Esposito3, James L. Duffy3, Derek Barton3, and Diana M. Stephens3 1

FR Carrick Institute for Clinical Ergonomics, Rehabilitation and Applied Neuroscience, Garden City, NY, USA 2 Carrick Institute for Graduate Studies, Cape Canaveral, Fl, USA 3 Life University Functional Neurology Center, Marietta, GA, USA

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Correspondence: Prof Dr Frederick Carrick, 2038941 Lake Drive, Cape Canaveral, Fl 32920 USA. E-Mail: [email protected]

Abstract Background: Many neurological syndromes are associated with pathology of balance and gait. The use of Computerized Dynamic Posturography is common in the practice of Neurology, yet there are no published guidelines or accepted procedures for its use in a Functional Neurology Application. Methods: The procedures and applications involving the use of Computerized Dynamic Post urography at a University Based Functional Neurology Clinic were reviewed. We have detailed the utilization of a variety of instruments specific to the diagnosis and rehabilitation of pathology of balance and gait and presented an overview and reference guide specific to this technology. Conclusions: The use of Computerized Dynamic Posturo graphy is recommended as a standard diagnostic tool in the Functional Neurology Clinic. An overview of the issues regarding human balance, vestibular and balance testing, basic clinical management of balance patients, and an illustration of some of the applications and benefits of using the technology are presented. We have experience in the utilization of a variety of technologies and we have detailed the use of the CAPS™ system that we find most useful in our applications.

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Frederick R. Carrick, Susan E. Esposito, James L. Duffy et al.

Keywords: Psoturography, Functional Neurology, Balance, Gait

Introduction Many neurological syndromes are associated with pathology of balance and gait. The use of Computerized Dynamic Posturography is common in the practice of Neurology, yet there are no published guidelines or accepted procedures for its use in a Functional Neurology Application. We have a large University Based Functional Neurology Clinic that receives patient referrals from around the globe with diverse neurological syndromes. We have used Computerized Dynamic Posturography for many years and have reviewed and detailed our utilization of a variety of instruments specific to the diagnosis and rehabilitation of pathology of balance and gait. We felt a need for both an overview and reference guide specific to this technology and have prepared a summary of the issues regarding human balance, vestibular and balance testing, basic clinical management of balance patients, and an illustration of some of the applications and benefits of using the technology.

Human (Postural) Balance In biomechanics, the study of human movement, “balance” is the ability to maintain the projection of the center of gravity (vertical line from center of gravity to the ground) of a body within the base of support with minimal postural sway. Functionally speaking “balance” is the ability to maintain the desired posture of the body against gravity when subjected to internal and external perturbations. Sway is the horizontal movement of the center of

gravity that occurs even when a person is apparently standing still. A certain amount of sway is essential and inevitable due to small perturbations within the body (e.g., breathing, cardiac activity, bowel movement, shifting body weight for one foot to the other or from heels to toes) or from external sources (e.g., air currents, floor vibration, contact with other persons). Balancing on two feet that are relatively small compared to the entire body is one of the most complicated activities a human routinely performs. The act is so complex that even healthy humans still fall, i.e., lose balance, in their early teenage years, albeit less and less frequently the more they’re balancing mechanisms improve. Because it requires a lot of practice, research has shown [1] that healthy humans reach their best balance performance only in their 4th decade of life. It has also shown that a healthy individual can still have extremely good balance at an advanced age [1]. Balance involves four different aspects: knowing where we are in space (both our head and each part of our body); sensing the perturbations to our stance; deciding on the appropriate corrective actions to compensate for those perturbations; and finally executing the appropriate corrective actions. The “sensing” of where we are in space and the recognition of the perturbations to our stance is accomplished by three systems: 1. Vestibular system: is part of the inner ear and senses linear and angular accelerations of the head. The linear and angular acceleration signals from the vestibular system are integrated by the vestibular nuclei in the brain, providing the brain the linear and angular velocities and the position of the head. The brain uses this information not only to maintain balance but also to stabilize the

The Use of Computerized Dynamic Posturography … images on the retina of the eyes to compensate for the motion of the head via the Vestibulo‑Ocular Reflex (VOR). Since slight head movements are present all the time, the VOR is very important for stabilizing vision: patients whose VOR is impaired find it difficult to read, because they cannot stabilize the eyes during small head tremors and movements, e.g., when walking. 2. Somatosensory system in general and proprioception in particular: these are aspects of the peripheral nervous system that provide information on the position of each articular joint, the contraction status of the skeletal muscles, and the presence of internal (e.g., cardiovascular, pulmonary and digestive activities), as well as external perturbing forces. 3. Visual system: provides similar and complementary information to the previous two systems (it allows us to know where the head and each body segment are, but also allows us to estimate visible external perturbations that are either perturbing or are about to perturb our stance). The information coming from the vestibular, proprioceptive/somatosensory and visual systems is largely redundant, i.e., these systems provide the brain with similar information. Standing and spending our lives in the very unstable upright position is so important for our species that we have several redundant systems to allow us to maintain balance even if a pathology affects negatively one, or sometimes even two, of those systems. This redundancy is also used in the learning and the “tuning” of the

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mechanisms. Redundancy however has its drawbacks: it can cause the brain to receive conflicting information leading to confusion (for instance motion sickness is often caused by conflicting sensory inputs to the brain). More importantly it can mask the presence of dysfunctions in some of the systems. In other words, it can allow a person to balance and function in an apparent normal way most of the time when the information from a dysfunctional system can be substituted with that obtained from other systems, thus hiding the existence of a problem. Unfortunately, it is not always possible to substitute the information from one system with that from another because the vestibular, proprioceptive/somatosensory and visual systems use different sensing modalities. In certain conditions (e.g., poor lighting, unstable or soft support surfaces, motion of the environment as a bus or an airplane) the redundancy can fail, making the dysfunction become apparent and compromising the ability to balance to the point of falling. Deciding on the appropriate actions to compensate for the perturbations of the stance occurs mostly in the central nervous system, both in the brain, and to a lesser extent in the spinal cord. A major role in maintaining balance is played, as in any muscular action, by the cerebellum. However, to some extent the entire central nervous system is involved, and the role of each part changes depending on the stance as well as the perturbation. Actuating the appropriate actions to maintain balance is, of course, the responsibility of the muscular system, mainly the skeletal muscles although all muscles might be used in some way in particularly difficult situations. It should therefore be clear that good balance requires the good functioning of the entire body. In other words, not just of the parts mentioned above but also of all the

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“supporting” systems and organs of the body such as the cardiovascular, respiratory, digestive systems, etc., since changes in any of them will eventually affect some or all of the systems used directly in the act of balancing. For instance, it appears quite obvious that a vestibular pathology will affect balance, and so will muscular weakness. But poor circulation or respiration will also cause poor balance as they impair both the central nervous system and the musculature. It is also important to remember that the balance abilities of an individual can change rapidly, even without the insurgence of pathologies. For instance a person's alertness, blood pressure and cardiac output can change even in a matter of seconds, mostly as a reaction to external conditions and the presence or absence of the need for physical action. Changes that can occur in a matter of minutes to hours include changes in tiredness, the amount of sugar and other nutrients in the blood, changes associated to digestion, the assumption of substances such as medications, alcohol, caffeine, nicotine, and others. Some changes might take days or weeks, like changes in weight and weight distribution, or changes of fitness level in the muscular but also cardiovascular and respiratory systems. These and other changes will almost always modify a person's ability to maintain balance.

Dizziness, Vertigo and Balance Dysfunctions Unfortunately because balance was not very well understood, over the years a lot of confusing terminology has been created and is still in use. First of all, a lot of confusion is created by the fact that when most persons, including clinicians, think of balance dysfunctions they think of acute and

often debilitating manifestations, mostly dizziness and, more specifically, vertigo or presyncope. The onset of dizziness usually occurs quite rapidly and violently and the affected persons clearly and quickly realize the difficulty in maintaining balance and the existence of a medical problem. According to the National Library of Medicine - Medical Subject Headings (MeSH) dizziness is “an imprecise term which may refer to a sense of spatial disorientation, motion of the environment, or lightheadedness” and is classified as a “sensation disorder” which is part of the “neurologic manifestations” of “nervous system diseases”. The term dizziness can be used to mean vertigo, presyncope, disequilibrium [2, 3], or a non-specific feeling such as giddiness or foolishness [3]. Dizziness is quite common, with an incidence of about 16% in middle-aged adults [4] and about 36% in elderly adults 70 years and older [5]. Dizziness is the primary complaint in 2.5% of all primary care visits [6]. Many conditions are associated with dizziness. However, the most common can be broken down as follows: 40% peripheral vestibular dysfunction, 10% central nervous system lesion, 25% presyncope/ dysequilibrium, 15% psychiatric disorder, and 10% nonspecific dizziness [3, 7]. Vertigo is a type of dizziness where there is a feeling of motion when one is stationary [11], and it is often associated with nausea and vomiting as well as difficulties standing or walking. According to MeSH, the definition of vertigo is “an illusion of movement, either of the external world revolving around the individual or of the individual revolving in space. Vertigo may be associated with disorders of the inner ear, vestibular nerve, brainstem, or cerebellar cortex. Lesions in the temporal lobe and parietal lobe may be associated with focal seizure that may feature vertigo as an ictal manifestation.

The Use of Computerized Dynamic Posturography … (From Adams et al., Principles of Neurology, 6th ed, pp. 300-1)”. Vertigo, like dizziness, is classified by MeSH as a “sensation disorder” which is part of the “neurologic manifestations” of “nervous system diseases” but, unlike dizziness in general, it is also classified as “vestibular disease”, a sub category of “otorhinolaryngologic diseases”. Vertigo is classified into either peripheral or central depending on the location of the dysfunction. Vertigo caused by problems within the inner ear or vestibular system is called "peripheral", "otologic" or "vestibular". The most common cause is benign paroxysmal positional vertigo (BPPV), but other causes include Ménière's disease, superior canal dehiscence syndrome, labyrinthitis and visual vertigo [12]. Any cause of inflammation such as common cold, influenza, and bacterial infections may cause transient vertigo if they involve the inner ear. Chemical insults (e.g., aminoglycosides and other ototoxic substances) or physical trauma (e.g., skull fractures) can also cause transient vertigo and permanent loss of vestibular function. Motion sickness is sometimes classified as a cause of peripheral vertigo. Vertigo caused by problems within the brain is called “central”, and is usually milder and has accompanying neurologic deficits such as slurred speech, double vision, or pathologic nystagmus. In general, the most common causes of vertigo are benign paroxysmal positional vertigo, concussions and vestibular migraine while less common causes include Ménière's disease and vestibular neuritis [11]. Presyncope is a state consisting of lightheadedness, muscular weakness, and feeling faint that is often the cause of dizziness. It does not result from primary central nervous system pathology, nor does it originate in the inner ear, but is most often cardiovascular in etiology. According the

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MeSH syncope is “a transient loss of consciousness and postural tone caused by diminished blood flow to the brain (i.e., brain ischemia)” and “presyncope refers to the sensation of lightheadedness and loss of strength that precedes a syncopal event or accompanies an incomplete syncope. (From Adams et al., Principles of Neurology, 6th ed, pp. 367-9).” But dizziness does not encompass all balance dysfunctions and all cases where a balance deficit exist. Because of phenomena such as habituation and compensation, many persons with pathologies or conditions that reduce balance below physiologic levels do not report dizziness except in acute conditions. For instance diabetes, poor blood circulation, decreased blood oxygen saturation, mild hypovolemia and hypotension, muscular weakness and many other conditions cause a decrease in balance with no manifestations commonly related to balance such as dizziness or vertigo. Similarly, permanent vestibular damage caused by trauma or ototoxicity often manifests with dizziness only in the acute phase and after few hour or days the subjects do not report any dizziness. The fact that dizziness (including vertigo, imbalance and faintness) is associated only with a small number of balance problems is proven by the fact that according to the U.S. Centers for Disease Control and Prevention (CDC) over 75% of Americans aged 70 years or older have a balance deficit [13] whereas about 36% of the elderly adults aged 70 years or older [5] report some type of dizziness. In our experience, approximately 2 out of 3 (66%) adults aged 65 years or older and 1 out of 3 (33%) adults under 65 years old suffer from a balance problem, whereas studies have shown 16% of middle aged adults report some type of dizziness [4]. So it seems dizziness in its various forms (vertigo, presyncope, disequilibrium,

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etc.) is present only in about half of the persons with a balance dysfunction! Another source of confusion originates from the fact that many people confuse “balance” with “vestibular”. This comes from the fact that the majority of dizziness cases (about 40% [3, 7]) are caused by peripheral vestibular dysfunction. Furthermore, as we have just seen, many people think that a balance disorder is the equivalent of dizziness. So it should not come as a surprise that so many think of balance dysfunctions as vestibular dysfunctions, while in fact vestibular pathologies with associated dizziness account for maybe 20% of all balance impairments (40% of dizziness patients who represent about 50% of the population with balance deficits). To successfully diagnose and treat persons with balance dysfunctions, it is necessary to stop thinking solely in terms of dizziness and vestibular system. It is a gross simplification that many clinicians have adopted for several reasons, including the fact that, if true, it would make their life much simpler by allowing them to focus their attention to only one area of the body when dealing with balance problems. Unfortunately, it is not that simple. As mentioned previously, good balance requires the good functioning of the entire body, and almost all pathologies of any part of the body cause a decrease in balance. This makes diagnosing and treating balance dysfunctions extremely complicated, time consuming, and difficult. Finally, it is worth mentioning another common terminology issue when talking about balance and balance dysfunctions. Often the terminology “normal” is used. This can be confusing because “normal” in statistical terms means “most frequent or common”, it does not mean “healthy” or “physiologic”. As more than half of the population aged 65 and older has a balance

deficit, “normal balance” in a statistical sense for that population actually means having a balance dysfunction, whereas “normal balance” commonly means “physiologic” i.e., “non-pathologic” balance. To avoid confusion, we feel that it would be more appropriate to use the terminology “physiologic balance” and “pathologic balance” instead of “normal balance” or “abnormal balance”.

Choice of Instrumentation Reference values are important for clinicians and the choice of technology is often dependent upon the integrity of instrumentation and established normative data. In our facility we were interested in the choice of instrumentation and have several types of posturography equipment from a variety of manufacturers. We feel that reference values are important in our clinical practice and in our research investigations. We have concluded that some manufacturers offering balance testing equipment use as reference values data obtained not from healthy subjects but from testing subjects randomly selected from the general population without consideration as to their actual health status. This can represent reference values obtained from a very large sample but it is actually difficult to find healthy subjects over 70 years old with no pathologies, and even more difficult and expensive to establish if they are actually healthy. We have noted a difference in reference values for all instrumentation available in our University Based Neurology center. The reference values for the CAPS™ from Vestibular Technologies, Cheyenne, WY, appear to be established with a greater rigor for detail and methodology in that [1] all subjects had to undergo a complete medical history evaluation as well as a

The Use of Computerized Dynamic Posturography … complete physical, neurological and otorhinolaryngologic visit to be considered healthy, and in many instances when there were doubts other testing like blood panels, MRI, CT and VNG were performed. This allows our team to obtain reference values based on the health status, so that when the CAPS™ equipment produces results that fall within the reference value range, we have a confidence in stating that a subject is healthy. We noted that our other posturographic instruments use the reference values established by research conducted on the CAPS™. Some of our instruments use reference values obtained without considering the health status of the subjects resulting in clinical conclusions suggesting that a subject is “normal” in the statistical sense, i.e., that the subject is like the majority of the population, nothing else. The choice of instrumentation in this center is based upon reliability of data and a correctness of approach that might be validated somewhat by the incidence of balance dysfunctions that is found to be in almost perfect agreement with the results of other studies such as those conducted by the CDC. As such we utilize many Computerized Dynamic Posturography systems but prefer the CAPS™.

Balance and Vestibular Testing There is confusion between the terms “balance” and “vestibular”, and many clinicians confuse balance testing with vestibular testing. However, balance testing and vestibular testing are not the same, they are only related by the fact that the vestibular system is one of the parts of the body used for maintaining balance and postural control. Whereas when performing “balance testing” we also test the vestibular system together with some or all the other

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parts of the body used to maintain balance, when performing “vestibular testing” we only test the vestibular system (and parts of the related central nervous system because we can't test the vestibular system in isolation). The terminology “balance testing” more appropriately indicates all testing that investigate balance in its entirety or use balance as the observed quantity, whereas “vestibular testing” should be used to indicate tests that investigate specifically the integrity and functionality of the vestibular system. This distinction, although it might seem as a simple matter of semantics, has very important practical consequences. Vestibular testing uses eye movements rather than balance as the observed quantity, and therefore will show abnormalities only if there are vestibular or central nervous system dysfunctions. However, these are present in only about 25% of all persons with a balance dysfunction. Similarly the term “balance testing”, since it uses balance as the observed quantity, will show abnormalities in all persons with a balance dysfunction. This is a significant difference that can change clinical applications. If clinicians limit themselves to vestibular testing and do not also embrace balance testing, about 50% of dizzy patients will go undiagnosed and untreated because they have no central or vestibular dysfunction; and most of the 75% of all persons with balance dysfunctions will go undiagnosed and untreated because they have no dizziness (so nobody knows they have a problem) or, if they do, they have no central or vestibular dysfunction. The 50% of all persons with balance dysfunctions that have acute symptoms like dizziness are in some ways the lucky ones, because even if undiagnosed and untreated, they know they have a balance problem and so they are careful in their movements and try to avoid falls. The other 50% (approximately 35% of

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the population 70 years old and older) most likely will not even realize they have a balance deficit until they fall, and even then they might not think there is anything clinically wrong with them and keep falling a few times before realizing there is a problem. Unfortunately, by the time they realize something is wrong with their balance, most of them will have already suffered the severe consequences of falls, including fractures and other severe injuries.

Vestibular Testing There are many common misconceptions/confusions when dealing with the topic of balance. It is at this time impossible to test the vestibular system alone because there is no methodology to measure the information transmitted from the vestibular system to the brain. It is only possible to test the vestibular system in conjunction with the brain. Unfortunately, it is currently also impossible to test the brain directly and it can only be investigated by observing its “outputs”, i.e., the external manifestations such as speech, muscular tone, movements, etc. Fortunately, the signals from the vestibular system are processed by the brain and used by the brain to move the eyes by what is referred to as the Vestibulo-Ocular Reflex (VOR). All vestibular testing (meaning all testing specific to the vestibular function and not non‑specific balance testing) relies on the observation or measurement of eye movements either fast (saccadic), slow (pursuit) or combined (nystagmus). Therefore, the terminology “vestibular testing” is also somewhat misleading, and our consensus suggests that it should be called “vestibulo-neuro-oculomotor testing”. Some tests used in “vestibular testing” (for instance the oculomotor tests, i.e., saccadic

tracking, smooth pursuit tracking, and optokinetic tracking) are actually neurologic tests that have little to do with the vestibular system, but are necessary to rule out the possibility that the eye movements seen when actually testing the vestibular system might actually be generated by some brain lesion and not a consequence of the signals coming from the vestibular system. It should be noted that of the six accelerations sensed by the vestibular system (the three angular accelerations sensed by the semicircular canals and the three linear accelerations sensed by the otolithic organs) only some elicit a VOR response (for instance pure anteriorposterior and medio-lateral linear accelerations do not cause the eyes to move, because no movement is required to stabilize the image on the retina). So conventional “vestibular testing” cannot test the entire the vestibular system and its functionality, albeit it is rare for only parts of the vestibular system and not the entire system (at least isolaterally) to be dysfunctional. The main purpose of vestibular testing is to find if there is a vestibular (peripheral) or a central nervous system (central) dysfunction, and if it is unilateral or bilateral. Together with an in-depth neurological assessment a highly trained clinician can determine the localization of a central dysfunction. Vestibular tests performed in our Center include electronystagmography (ENG) (and its modern version videonystagmography (VNG)) testing battery, the Dix-Hallpike Maneuver, Pneumatic Otoscopy, Head Shake Nystagmus test, Head Thrust Test, positional and positioning tests, caloric tests and rotational chair tests. In order to perform these tests in a measured and quantifying manner at our facility, it requires expensive equipment (rotational chair, and ENG and VNG equipment), time, and sometimes there may be severe discomfort to patients (for

The Use of Computerized Dynamic Posturography … instance rotational chair tests and caloric tests can induce severe vertigo, nausea and sometimes vomiting). However, with proper training and observational skill, several tests can be performed quickly (albeit subjectively and observationally without recording, measurement or quantification) as part of our clinical examination without much patient discomfort, e.g., observing the patient's eyes without the use of any equipment or using inexpensive tools like Frenzel lenses. Because of the time, cost and sometimes discomfort of many of the instrumented vestibular tests, we perform a complete evaluation of the patient's medical history and a detailed physical examination that includes specialized neurological and vestibular evaluations. Because peripheral vestibular dysfunctions are often associated with hearing loss, a hearing screening is also performed. In subjects with any form of dizziness (including vertigo, presyncope, disequilibrium) vestibular testing will indicate the presence of central lesions in about 10% of the cases, and the presence of vestibular lesions in about 40% of the subjects examined. Why the incidence of central lesion and vestibular lesions in the roughly 50% of the population that are affected by balance dysfunctions do not present with dizziness is unclear because of the lack of studies. However, it is possible that because of habituation and compensatory mechanisms their incidence could be as high as in the population that presents with dizziness.

Balance Testing “Balance testing” indicates all testing that investigate balance in its entirety and uses balance as the observed quantity. Most

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balance deficits exist without the subject or the physician being able to notice them because in every day conditions compensatory effects mask them. Balance is so essential to a human that several compensatory mechanisms exist to allow a person to maintain good balance at least in the most common situations (good visibility, hard and non slippery surface, without external perturbations). Balance testing is therefore essential to identify subjects with balance dysfunctions. Balance testing has a history dating back almost 200 years. One of the first tests was the Romberg’s test commonly performed during the neurological examination to evaluate the integrity of dorsal columns of the spinal cord. Moritz Heinrich von Romberg first described it in 1840. Since then, many other balance tests have been developed. Several are based on observing the subject (e.g., Modified Romberg’s, the Berg Balance Scale, the Tinetti Balance Test of the PerformanceOriented Assessment of Mobility Problems, the Balance Error Scoring System or BESS, the Y Balance Test Protocol), whereas others are based on measurements of body movements that is presently almost always automated and computerized (mainly posturography). Observation based balance tests (including those called “objective” because they use scales and scores and should therefore be more appropriately called “quantitative” rather than “objective”) are useful in our Neurology Center by advanced trained Fellowship level Clinicians. Such tests appear to be very attractive to general practitioners, as they require minimal investment in equipment. However, they have significant drawbacks for general practice because they are based on specialized observation such as available in this Neurology Center and not on automatic measurements. These tests require highly

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trained clinical staff that are Board Certified in Neurology to administer and observe/score the outcomes correctly. Such testing is time consuming and requires several minutes to complete, usually in the order of 10 to 15 minutes. The tests are subject to subjectivity as the clinician has to observe and evaluate the subject's movement, and as much as the test methodology tries to minimize the subjectivity, it is still inherent and unavoidable, as several studies have shown [14-17]. Efforts to increase inter examiner reliability in our facility are continuous and ongoing and we are impressed by our outcomes. It is agreed, however, that even with advanced training, most specialists cannot detect small abnormalities or changes in balance, and the minimum amount of change detectable depends on the clinician observing the test. There are many examples that might be useful to further explain the limitation of observation based balance testing, eg. consider a person walking on a tight rope or any narrow support: such a person usually appears to “sway” a lot, but in fact considering the proper and scientific definition of sway as “the movement of the center of mass of the body in the horizontal plane”, he or she is swaying very little (the weight has to stay on the very narrow support to avoid falling) and the balance is extremely good. Conversely, a person suffering from bradykinesia or even akinesia, such as that caused by Parkinson's disease, looks steady and immobile as a rock, but in fact sways a lot and has very poor balance because of the inability to control the movements of the center of mass of the body, with small perturbation typically resulting in a fall. Balance tests based on measurements of body movements are generally, and again somewhat incorrectly, referred to as posturography (it is incorrect because the term posturography actually refers to the

study of posture, not balance, although the two are related). Ideally, these tests would measure the actual sway of the body. Unfortunately, this is practically impossible to do and requires the measurement of the mass distribution and movement of each and every tissue and fluid in the body. Some systems have been developed that use accelerometers and similar motion sensors attached to the skin or strapped onto the body to measure the movement of the trunk, pelvis, head, and other body segments. These systems require careful and time consuming setup, only measure the movement of the location of the body they are attached or strapped to, can not measure internal movements of body masses (for instance those caused by respiratory, cardiovascular and peristaltic activity), and suffer from motion artifacts of the skin relative to the body making them inaccurate. All these issues make them ill suited for clinical practice. But even if sway cannot be practically measured, it is possible to measure the movements of the instantaneous Center of Pressure (CoP) of the ground reaction force, i.e., the point on the support surface where the resultant ground reaction force is applied. Research has shown that CoP movements track and correlate well with sway [18]. So computerized posturography systems such as the CAPS™ used in our facility, utilize force platforms to measure the movements of the CoP (some of our other in house systems utilize insoles or pressure sensitive mats, but whereas these can provide a map of the pressures under the feet, they have been found not sufficiently accurate to determine the movements of the CoP with the necessary resolution and accuracy). Several types of tests can be performed using these computerized posturography systems, but by far the most common ones are variations of the static balance test in which the person being tested tries to

The Use of Computerized Dynamic Posturography … minimize the sway of the body. The most commonly used variations of static tests comprise the modified Clinical Test of Sensor Integration in Balance (mCTSIB) protocol. It consists of four tests: Eyes Open on Firm Surface (NSEO), Eyes Closed on Firm Surface (NSEC), Eyes Open on Unstable Surface/Foam (PSEO), and Eyes Closed on Unstable Surface/Foam (PSEC). We use these tests to identify persons whose balance is pathologic, to provide some initial indication as to the localization of the problem (vestibular, visual, proprioceptive, or central) and to monitor the effects of interventions. We also use them to research the effects of various pathologies or conditions on balance and postural stability. To obtain meaningful results from any clinical test, it is necessary to understand the factors that might cause a change in the results. This of course holds true also for posturography and balance testing. Particularly, since balance involves the entire body, it can be affected by almost anything that affects the subject being tested. Postural control, the act of maintaining, achieving or restoring a state of balance during any posture or activity, may be affected by strategies that are either predictive or reactive [19]. Such strategies can be affected by several factors, one of which can be the instructions given to the subject [20]. Other factors include the time of day, possibly because of combined effects of fatigue and varying levels of nutrients [21-23]. Postural sway is increased in individuals who have been sleep deprived [24-26]. In fact, stability and sway intensity with eyes closed can show a circadian pattern with a peak at early morning hours and a recovery at 10:00 AM the following day [26]. Stretching of the calf muscles has the effect of increasing postural sway [27]. Sounds at low and middle frequencies result in a significant increase of body sway on the lateral plane and in the closed-eyes

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condition, suggesting that sound activates the vestibular system [28]. The response to different sound stimuli even affects the posture (lying or sitting) of 6-week-old infants [29] and is innately linked to the motor responses of humans. Unexpected sounds can elicit a startle response that produces muscle contractions throughout the body and may produce excessive and inappropriately directed contractions that may change posturographic readings [30]. The influence of sound image motion on postural reactions induces body displacement in the direction opposite to that of sound image [31] and the center of gravity deviates during exposure to a sound stimulus towards the side opposite the direction of movement of the sound source [32]. The integration between visual and vestibular input during quiet standing suggests a dual role for vestibular information. Vestibular information in quiet standing has a role in maintaining whole body postural stability, and may be differentially attenuated by visual stimulation [33]. Sound can also activate a short latency vestibulocollic reflex that appears to arise from the saccule, and affects otolith function [34]. Even spoken words of an examiner or assistant can change postural control in subjects who are undergoing posturographic testing, with changes dependent upon what is being said. We utilize hearing attenuating devises to ensure a minimizing of environmental noise. While a non-meaningful auditory stimulation does not lead to postural control modification, a meaningful auditory task allows a reduction in postural parameter values, and therefore a better stabilization of posture [35]. Mechanical vibration noise can be used to improve motor control in humans such that the postural sway of both young and elderly individuals during quiet standing can be significantly reduced by a sub-sensory mechanical noise to the feet [36]. Changes

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in human postural stability may be observed if a loss of vision or any vision impairment appears [37] and conversely improvements in stability might be obtained if some component of visual stimulation is allowed to occur during a posturographic test. The inter-relationship between eye position and neck muscle activity does affect the control of neck posture and movement [38]. A light stimulus from a peripheral source can affect human stability so that having the patient close his/her eyes may not be adequate. Peripheral rather than central vision contributes to maintaining a stable standing posture, with postural sway being influenced more in the direction of stimulus observation, or head/gaze direction, than in the direction of trunk orientation [39]. Even ocular dominance affects postural stability with the non-dominant eye being more concerned with postural control than the dominant eye [40]. Given all of the above, it should be clear that proper balance testing requires controlling the test conditions, as these can affect the results. In other words, balance testing offers an instantaneous insight as to the conditions of the subject and how the surrounding environment affects the subject. We keep this in mind during testing, and find that it can actually be used to our advantage by eliciting in the subject small temporary changes in the conditions that can provide insight about the areas that are more problematic for that patient. It should also be noted that this is not at all different from other types of medical tests: arterial blood pressure measures can be greatly affected by the “instantaneous” condition of the subject; sugar blood levels can change rapidly because of eating, exercise and other metabolic events; the same can be said for many more tests. In terms of repeatability of the balance measures, in particular of the static tests comprising the mCTSIB, research has

shown that with an instrument like the CAPS™ the variability in the test results is all due to changes in the subjects [41], and that a change in the stability score of more than 1.1 points for the stable surface tests and of more than 2.1 points for the tests on unstable surface is statistically significant to a 95% confidence level. Balance testing and in particular posturography can measure, if the instrument is sensitive and accurate enough, extremely minute balancing movements of a person. Unlike vestibular testing, balance testing and in particular posturography will indicate the presence of a balance dysfunction in the vast majority of subjects that, at the time of testing, have one, even if they do not complain of dizziness or balance impairment. This is about 1 out of 3 (33%) adults below 65 years of age, 2 out of 3 (66%) adults 65 years old and older, and 3 out of 4 (75%) adults over 70 years of age and older. Since balance testing and posturography investigate balance and involves the entire body, it should be apparent what has taken years for research to show: balance testing and posturography have high sensitivity to the general health status of a subject, but very low specificity. In other words, all research has shown non-physiologic balance testing results when pathology is present, but from the results it is often very difficult to arrive at a specific diagnosis. We can think of balance testing and posturography as a generalized version of other non specific but indicative clinical tests, e.g., arterial blood pressure, cholesterol, white blood cell count: non physiologic results suggest a pathology, but do not (and cannot) provide a specific diagnosis. For instance, a patient might have abnormally high blood pressure, but alone the finding does not tell the cause of it and therefore does not provide a specific diagnosis, rather it points to a series of possibilities that should be

The Use of Computerized Dynamic Posturography … investigated further using other diagnostic procedures and tests. Furthermore, as with any clinical test, the results reflect the status of the subject at that specific point in time that in the case of balance can change quite rapidly for a variety of reasons. These characteristics do not make balance testing or posturography any less useful in the clinical practice, but, as it is the case with any diagnostic test, it is important to know the limitations to maximize the effectiveness and usefulness of the test.

Balance Testing in Clinical Practice We wanted to define the role of balance testing and posturography in our clinical practice. We wanted to know how to use these tools effectively from a clinical and economic perspective to improve the health and function of humankind? We believe there are very different schools of thought in this matter. Several of those involved in balance, be they researchers, clinicians or engineers developing medical devices, apparently believe that balance testing can and should be used for diagnostic purposes, i.e., to find out where a balance dysfunction originates. This has lead to the creation of long and complicated observation-based test protocols that are expensive to use in terms of time (and time is money), as well as to the development of costly, large and sophisticated posturography equipment with moving platforms, moving visual environments and other ways of perturbing or confusing the subject's balance. And as a consequence, it usually takes a long time to test a person. Years of research and hundreds of scientific studies have been performed in an attempt to validate their

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diagnostic capabilities, unfortunately without much success. In fact, after decades of research, posturography (the only balance testing that is not based on observation and provides documented, automated measures and therefore has a specific procedural and reimbursement codes) is still considered experimental by many health organizations. In our opinion, using posturography as a diagnostic tool is faulted because, as previously discussed, balance depends on the functioning of the entire body, and therefore balance testing is intrinsically nonspecific. Although attempts can be made to isolate the effect of the different body systems, so many parts of the body are still involved that there is no way to make the test results specific enough for a diagnosis except in very few cases. We understand that balance testing is non-specific and therefore is sometimes considered of limited diagnostic value. However, we realize that balance testing can be useful in the screening and identification of persons affected by balance dysfunctions that relate to the health status of a person and to falls (a major health issue in the elderly population). Again, this has lead to the creation of long and complicated observation-based test protocols (e.g., the Berg Balance Scale, the Tinetti Balance Test of the Performance-Oriented Assessment of Mobility Problems). These suffer from all the limitations we have discussed earlier in this report. There is a major problem with this approach in that it neglects the reality that balance can change very quickly. We believe that the usefulness of these balance testing protocols is very limited simply because they take too much time, and therefore they cannot be repeated as often as the changes in a persons' balance would require. The assumption behind these test protocols is that an assessment performed at a specific point in time can be representative of the person's balance for a

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long time, i.e., that the balance will not change significantly for some time. Some researchers go as far as trying to correlate, either retrospectively or prospectively, the results of a single balance assessment with balance issues and falls 3, 6 or even 12 months away. We believe that balance testing is nonspecific and therefore of limited diagnostic value, but that it is a superior tool that is essential for the screening and identification of persons affected by balance dysfunctions. We also believe that balance can change in a short time and that a person should be tested very often to detect any changes in balance with the goal of catching dysfunctions as soon as they appear, ideally before they result in falls and injuries. All of this made us realize that to be useful clinically any balance testing has to be extremely fast, sensitive and accurate enough to detect any change in balance, not require highly trained personnel to perform or interpret, and have very low direct and indirect cost per test (i.e., not only the initial costs to purchase the necessary tools, but also the material and personnel costs necessary for the training and those to perform the testing, including the costs associated with the space required if dedicated to the balance testing). We believe that this is possible by using a computerized force platform and a dynamic posturography version of a subset of the tests of the old Modified Romberg's balance test, i.e., using one or more of the tests that constitute the mCTSIB. This solution allows us to combine the proven characteristics of the Romberg's test with the objectivity, sensitivity, accuracy and automated analysis of posturography, eliminating the need of highly trained personnel and allowing us to test a person in a very short time. The CAPS™ products are the most popular posturography systems that we use

and have been awarded a patent by the U.S. Patent office on the ability to assess a person's balance, weight and BMI in 60s or less.

Different Clinical Approaches to Balance Testing Generally speaking there are two quite different approaches to clinically managing persons with balance dysfunctions: a traditional approach that up to now has been able to help only a relatively modest number of the many men and women with a balance deficit and that has been able to only marginally reduce the number of falls in the elderly; and a new approach, unfortunately still embraced by a very small number of clinicians and medical personnel, that has the potential to help the vast majority of persons with balance dysfunctions and to hopefully decrease the incidence of falls and fall related injuries in the aging population. These approaches differ in the screening of the general population, in the management in primary care settings and in the management of residents of institutional facilities (e.g., hospitals, rehabilitation facilities, nursing homes, assisted living facilities).

Traditional Approach Whereas screenings for many other conditions (e.g., weight and Body Mass Index, vision deficits, high cholesterol and hypertension) are offered at pharmacies, health fairs and other community settings, there is currently no screening of the general population for balance dysfunction. In primary care settings, balance is seldom evaluated. Unfortunately many primary care clinicians are infrequently

The Use of Computerized Dynamic Posturography … educated and trained in managing balance patients. If the patient reports dizziness and/or repeated falls a basic evaluation using some observational based balance tests might be performed. In case of persistent dizziness and sometimes when a vestibular dysfunction is suspected, the patient might be referred to us or another specialist (usually an otolaryngologist or sometimes an audiologist or a functional neurologist). In case of transient dizziness and vertigo (e.g., BPPV), rather than diagnosing the actual cause, the patient is often prescribed antivertigo/antiemetic medications (e.g., Meclizine) and told to take it when an episode of vertigo occurs to help waiting it pass. In case of apparent neuromuscular issues, the patient is prescribed general physical therapy non-specific for a balance issue. When medication is prescribed for any reason, only in rare instances the effect of the medication regimen on the patient's balance is considered or evaluated. Even in case of primary care clinician trained in balance issues, balance is seldom evaluated unless the patient reports dizziness or falls. However, at least when presenting these symptoms, the patient is usually further tested and evaluated and is often referred for vestibular testing and/or other diagnostic procedures that relate mostly to the vestibular system or its central nervous system pathways. But even when the primary care clinician is somewhat trained to deal with balance pathologies, unless the subject is symptomatic, balance deficits are often not assessed, nor the possible effects of medications and pathologies on balance are evaluated and explained to the patient. In institutional settings, because of the pressure by accrediting institutions like The Joint Commission (formerly the Joint Commission on Accreditation of Healthcare Organizations or JCAHO) to prevent falls, patients are usually evaluated for balance dysfunctions and fall risk. This is usually

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done using observational based balance tests, questionnaires and other tools developed to evaluate the risk of falls. In presence of acute or severely debilitating pathologies and in non-ambulatory patients, sometimes the only thing that can realistically be done is to take preventive measures rather than addressing the underlying balance deficit. Unfortunately, in less severe situations when a patient is ambulatory, balance dysfunctions, even if identified, are often undiagnosed and untreated, or at most only general rehabilitative measures are taken. This is frequently the case in assisted living settings. The major issue regarding the current approach to the management of balance impairments in institutional settings is the fact that balance testing is not performed often enough. The main reasons are that observational based balance tests take too long, and the speed at which changes in balance can occur is underestimated. The reasons why balance impairments are conventionally managed this way are several. Among them are: an insufficient knowledge of the issues regarding balance; insufficient sensibility to the consequences of balance dysfunctions; the almost complete absence of specific training of medical personnel; the fact that balance issues are seen as the domain and responsibility of specialists; the fact that balance testing as is usually done, be it using observation based tests or posturography, is too expensive in terms of time and training. This last reason is, in our opinion, possibly the main reason. In other words, the lack of fast, objective and automated ways to test balance is one of the main causes of why balance dysfunctions are currently managed the way they are. This approach is leaving unidentified, and therefore untreated, almost all persons with balance dysfunctions that do not

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present with obvious manifestations (as indicated earlier about 50% of those with balance problems and approximately 16% of the adult population younger than 65 years and 33% of the population aged 65 and older). It also leaves many of those with an identified balance deficit without diagnosis and therefore without a real and effective treatment. This approach also wastes the opportunity offered by balance testing to provide a general and quite comprehensive assessment of a person's general health and therefore to be used as a screening tool for providing an early indication of the insurgence of pathologies. Finally, the difficulty of frequently assessing balance severely hinders efforts to reduce falls.

New Approach In the new approach to clinically managing persons with balance dysfunctions, the general population is offered balance screening in conjunction with other health screening in many community settings and the general population is educated and aware of balance dysfunctions, falls and the possible consequences. In primary care settings such as ours, balance is tested and evaluated as regularly as blood pressure and weight or even more often, ideally as part of the intake procedures of every visit. Balance is used as an indicator of the insurgence and progress of pathologies. Those persons with balance dysfunction are further evaluated with vestibular and other diagnostic testing until the etiology of the balance dysfunctions are identified. Unlike in the traditional approach, balance is not synonymous with vestibular, therefore the evaluation includes a review of the medications as well as

nutrition, physical condition, lifestyle, neurological conditions and in general an evaluation of the entire well being of the patient. If possible, the underlying cause of the dysfunction is treated and changes in balance are monitored throughout the entire treatment. Patients are referred to us for specialized balance rehabilitation and their treatment does not end until their balancing ability is maximized given their general health conditions. The possible effects that pathologies, medications and treatments might have on balance are explained to the patient and are actually evaluated and quantified for every patient by following up with repeated balance testing. Patients and their families are then educated as to the possible future consequences of balance dysfunctions, including the increased risk of falls later in life. Patients whose balance cannot be restored to the levels of a healthy person or that are at an increased risk of injuries from falls are educated using a functional neurology/occupational therapy approach (e.g., they are instructed to wear proper shoes, to recognize and avoid situations where their balance might be challenged to its limits, to remove as much as possible from their homes and workplaces things that might cause them to fall). We maintain that the balance of ambulatory persons should be regularly evaluated, possibly as often as their blood pressure or other health condition indicators are evaluated (even multiple times a day) to notice changes in their health status and their risk of falls. Changes in balance may be quickly noticed and their cause ascertained (just like for blood pressure or body temperature), and patients are informed of the status of their balance and warned of the associated fall risks. The etiology of the balance dysfunctions is identified, if necessary by further clinical evaluations (including a review of the medications as well as

The Use of Computerized Dynamic Posturography … nutrition, physical condition, lifestyle, neurological conditions and in general an evaluation of the entire well being of the patient) or our in house vestibular, neurologic and other diagnostic testing. If possible, the underlying cause of the dysfunction is treated and changes in balance are monitored throughout the entire treatment. Patients are referred to us for specialized balance and vestibular rehabilitation and their treatment does not end until their balancing ability is maximized given their general health conditions. Persons whose balance cannot be restored to the levels of a healthy person or that are at an increased risk of injuries from falls are educated as to what to do and what to avoid in their daily routines (e.g., do not shuffle their feet, place their walking aids appropriately so not to trip over them, use rails whenever they are available, do not move around in the dark, etc.), active interventions on their environment are performed to remove as much as possible any external potentially fall causing obstacles (rugs, small tables, power cords, etc.) and close monitoring of their daily activities is performed to assess the effectiveness of these preventive measures and avoid as much as possible the devastating consequences of falls. This approach requires great educational efforts to increase the general awareness of balance dysfunctions and the associated increased risks of falls in an advanced age, and especially to train clinical personnel to identify and manage balance issues. But what this approach really depends upon is the availability of ways to assess and quantify balance that are similar to the technology available to quantify blood pressure, body temperature or blood oxygen saturation level. In other words, devices that are easy to use, fast, accurate, sensitive to minimal changes, do not require particular skills to be

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used and to interpret the results thus do not require to be used only by highly trained personnel, and have a negligible cost per use.

The CAPS™ As a Preferential Instrument We have and use many posturography systems, but use the CAPS™ in our research and in all cases where we want exacting data. While we utilize other systems in screening, the CAPS™ allows us to better address the needs of the new approach to the clinical management of balance dysfunctions. Several unique characteristics make the CAPS™ different and better than other posturography devices we utilize for this purpose. The CAPS™ force platform is highly portable and we can take it to external areas, labs and sporting events. It was the first posturographic device and one of the first medical devices in general capable of being run from a battery powered portable computer without requiring a power line; and it was the first and still is one of the few balance assessing tools that does not require any special setup such as leveling of the platform on the floor. The extreme portability and power concerns allow us to use it wherever the need for a balance test or screening might arise, and when used in a fixed location it takes up as little room as possible (similarly to a clinician's scale), without occupying too much of the space that in a clinical environment is often at a premium. The CAPS™ force platform is extremely sensitive and accurate, allowing us to detect even minute changes in balance that might provide an early indication of changes in a person's body before these become important and difficult to revert.

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Most importantly, we find that it is easy to use and is faster than other systems. The other balance testing equipment we use are largely designed mainly for diagnostic purposes, requiring a relatively long set-up and testing time. The CAPS™ force platform and software allow us to objectively and quantitatively assess a subject's balance, weight and BMI in less than 60s. We also have interns, residents and doctoral students operate the equipment without requiring any special training. The system software allows us to automatically compare the results with reference values established for healthy subjects. We find the CAPS™ ideal when we conduct advanced balance, neuromotor, and physical performance testing for in depth, nonscreening evaluations. It has abilities that other systems do not have and several of the characteristics of the CAPS™ are unique with several patents that protect its design features and technology. We need portability, usability and speed in our applications and have realized that posturography is much more useful for nonspecific balance testing assessments than for diagnostic purposes. This portability is not associated with options that include sliding and/or tilting platforms and moving visual environments to see how the different sensory inputs affect balance. The CAPS™ that we use, allows us to concentrate on marrying the traditional Modified Romberg tests with modern posturographic technology replacing the role of the trained observer and creating a sort of instrumented Modified Romberg that is much more sensitive, accurate and objective than the original observational tests and can be performed faster. It is ideal for a Functional Neurological Application and is a very sophisticated and user-friendly posturography device that measures a subject's Center of Pressure (CoP) movements during standing.

Hundreds of scientific and clinical publications have been written on the applications of these types of measurements to the clinical practice. Most, if not all, of that literature applies to the CAPS™ as well as to any other posturography devices that measure the subject's sway by means of Center of Pressure movement detection. We find that the other instruments we use do not have the resolution of the CAPS™ and have less sensitivity and more noise. This is a crucial point, so it warrants expressing the concept in another way. Think of MRI or CT machines: any application and study done on a model of MRI or CT machine is applicable to any equal or better model of MRI or CT machine (i.e., a machine having similar or more resolution and/or faster acquisition times), but not vice-versa, since something that can be seen and appreciated on a high resolution imaging scanner might not be visible in lower resolution models. The same holds true for posturography and any other type of medical instrument, from EKG to microscopes.

The CAPS™ and Its Clinical Applications We use the CAPS™ in a variety of applications: 1. As a fast general assessment/screening tool to provide a comprehensive evaluation of balance and the health status of a person and to identify those with an asymptomatic balance dysfunction by comparing the result of the subject's tests with the reference values obtained for healthy subjects. 2. As a verification that a dizzy patient does in fact have a balance

The Use of Computerized Dynamic Posturography …

3.

4.

5.

6.

dysfunction as in about 15% of the cases dizziness has a psychiatric origin. As a non-specific diagnostic tool to determine, by changing the sensory input to the patient and together with a complete medical history and physical evaluation, which of the major systems involved in balance might be affected and to aid in the planning of the treatment. As a fast follow-up to assess and document changes induced in a patient by treatments (functional neurologic, medical, surgical, physiotherapy, orthotic, etc.) or by the advancing of a pathology through the comparison of the test results with baseline values obtained for the same person at the beginning of the monitoring period. As a fall risk assessment tool that instead of trying to predict falls far in advance based on a single evaluation allows the frequent testing necessary to use short term instead of long term predictions in the management of fall risk (it is easier and much more accurate to make short term predictions than long term ones, just think of weather forecasts). As an educational tool to show persons if they have a balance issue and how lifestyle or treatments might be affecting them.

Our CAPS™ Protocols for Neurological Diagnostic Testing CAPS™ We have a standard procedure for CAPS™ utilization that we have written as a computer template that allows transition

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from one test parameter to the next in an automated fashion. We have found it efficient and comprehensive. Our procedures are all measured using the CAPS™ balance track software that allows us to look at all measurements in great detail, both in live time and in review.             

Eyes open Head Neutral Non Perturbed Surface Eyes closed Head Neutral Non Perturbed Surface Eyes open Head Neutral Limits of Stability Eyes open Head Neutral Perturbed Surface Eyes closed Head Neutral Perturbed Surface Eyes open Head in Max Right Yaw Perturbed Surface Eyes closed Head in Max Right Yaw Perturbed Surface Eyes open Head in Max Left Yaw Perturbed Surface Eyes closed Head in Max Left Yaw Perturbed Surface Eyes open Head in Max Anterior Pitch Perturbed Surface Eyes closed Head in Max Anterior Pitch Perturbed Surface Eyes open Head in Max Posterior Pitch Perturbed Surface Eyes closed Head in Max Posterior Pitch Perturbed Surface

Using the CAPS™ for Fast General Assessment/Screening To perform a general assessment/screening it is necessary to perform a test in the same conditions for which the reference values have been collected. This means a static balance test (the one where the subject stands upright

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trying to sway the least amount possible) with the subject standing feet shoulder width, looking straight ahead (even with the eyes closed the subject should be instructed to look forward), relaxed and breathing normally. It is possible to perform the testing either with the subject standing on the plate surface, or standing on the perturbing foam cushion positioned on top of the platform. The subject can be tested with eyes open or eyes closed. However, as standing on the hard surface with eyes open is obviously an easy task that does not put much stress on the balance, it is recommended that for screening purposes the subject be tested with eyes closed standing on the foam cushion (the most difficult situation). At the end of the test, the software will automatically compare the subject's test results with the age based reference values and provide a classification of the subject's balance into one of five categories: Healthy Balance, Mildly Reduced, Moderately Reduced, Severely Reduced, Profoundly Reduced. A subject whose balance is classified as Healthy Balance has a 25% probability of a false negative (i.e., the subject has a pathology but the test does not indicate so). A subject whose balance is classified as Mildly Reduced has a probability of a false positive (i.e., the probability that the test shows a balance pathology but in fact there is none) between 10% (at the upper limit) and 0.5% (at the lower limit): subjects scoring in this range typically do not suffer from a pathology but only from a temporary condition reducing their balance (like lack of sleep, congestion, allergies, etc.) A subject whose balance is classified as Moderately Reduced, Severely Reduced, or Profoundly Reduced has at most less than a 0.5% probability of a false positive and should definitely be assessed further. The assessment would usually include a complete medical history and

physical examination. Most often, especially in elderly subjects, a vestibular problem is one of the causes of the balance impairment, although it might not be the only one. As the vestibular system has a lot in common with auditory systems, usually there is a co‑morbidity between vestibular and auditory deficits. It is therefore advisable, if a vestibular deficit is suspected, to proceed with some hearing testing, even if only at a screening level, before any other test is ordered. Screening for balance problems, especially at the primary care level, is extremely important. According to the US CDC over 3 out of 4 (75%) adults over 70 years old suffer from a balance dysfunction (it is the most common disability in the US elderly population), and in ours and our customers' experience about 2 out of 3 (66%) adults over 65 years old and 1 out of 3 (33%) adults below 65 years old suffer from a balance problem. For the clinician, the sometimes minimal decrease in balance and postural stability that a machine like the CAPS™ can detect (and that most often is undetectable by observation alone, even with trained eyes) can be the first sign that something is wrong with a patient. For the patients, knowing and treating their balance issues might prevent falls and the serious consequences and costs usually associated with such events.

Using the CAPS™ to Aid in the Diagnosis and in Treatment Planning One of the main advantages of the CAPS™ is the ability to perform objective and very sensitive balance testing in very little time. This can be used to the clinician's advantage to aid in the diagnosis and in treatment planning. The main idea is to provoke temporary changes in a patient and

The Use of Computerized Dynamic Posturography … to evaluate the consequences on his/her balance. For instance, by altering the presence or absence of visual inputs, easily done by testing a subject first with eyes open and then closed, it is possible to evaluate how much the subject relies on vision to maintain balance. A subject that relies a lot on vision (i.e., one for which the tests with eyes closed show a much lower ability to maintain balance than with eyes open with all other conditions being the same) might do so because the vestibular and/or proprioceptive information are deficient. Similarly, altering the proprioceptive inputs, either using the CAPS™ perturbing foam cushion or vibratory stimuli to the muscles or to the spinal receptors by applying a vibrating tuning fork, can identify a situation where the subject relies too much on proprioceptive or somatosensory signals for balance. The theoretical basis of the mCTSIB test is exactly this, to see how the subject performs when the combination of vestibular, visual, and proprioceptive/somatosensory information is changed in a controlled manner. Similarly, lower extremities muscular weakness can be investigated and evaluated by having the subject stand on the platform, with or without foam cushion, for a few minutes and repeating the test every so often to see how quickly the ability to maintain balance deteriorates. In case of a subject suspected of having Parkinson's disease without motor symptoms such as tremor or bradykinesia, it is possible to administer a low dose of levodopa and see if and how much balance improves. We are currently studying the effects of drugs and medication on balance and whole body responses in collaboration with another institution. If a cerebellar lesion or weakness is suspected, we like to stimulate the identified side of cerebellar dysfunction using hand or

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upper and/or lower extremity complex dexterity exercises and then immediately test the subject looking for an immediate improvement of the subject's ability to maintain balance. This allows us to confirm a diagnostic thought and/or application. Having the subject position the head appropriately in space so that only specific organs of the vestibular system are active can also test various aspects of vestibular function. For instance flexing or extending the head, or tilting or rotating the head, so that specific semicircular canals lay in the horizontal plane can be used to evaluate if there is problem in one of them. The possibilities are many and it is impossible to list them all, but the concept should be clear. We try to alter even slightly the system or part of the body suspected of having a problem and see if there is a change in the ability to maintain balance, being advised that sometimes the change might actually be for the worst, indicating that such intervention is not the way to make the subject's ability to maintain balance better. An often overlooked issue in our treatments is the effect that medications have on balance. Although sometimes this is an unavoidable side effect, it is important for the Functional Neurologist to be aware and often time there are recommendations to adjust the dosage of drugs to minimize the effect on balance and to warn and educate the patients on the possible consequences. All too often, for instance, blood pressure lowering medication is prescribed without verifying the functional consequences, with the result that the pressure is lowered to the point of impairing the patient's ability to function and to maintain balance. It is also essential that any treatment ends with as much a restoration of the patient's abilities as possible. All too often little attention is paid to the issue of balance and treatments are considered concluded

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without taking into consideration if a person's balance has been restored. Balance testing is therefore indicated for verifying if at the end of any treatment the patient might benefit from balance rehabilitation therapy and then to monitor its progress.

Using the CAPS™ to Monitor and Document Changes As maintaining balance and postural stability involve the proper functioning of the entire body, it is possible to make the bold statement that any improvement in a person's health conditions should be accompanied by an improvement in balance and postural stability. Accordingly, no matter what the intervention or treatment or progress of pathology is, balance testing can be used to monitor and document changes. As the CAPS™ is a very sensitive instrument and using it to perform balance tests takes very little time, this can and should be done not only pre‑ and post‑, but also during treatment. For instance, during rehabilitative sessions including exercise and physiotherapy, the CAPS™ can be used to test if the subject is actually fatiguing to the point where it would be better to interrupt the session. Or it can show that the benefits of repeating a certain exercise have reached their maximum, thereby signaling the clinician that it might be time to change exercise type or regimen rather than continuing and getting only diminishing returns. Although rehabilitative therapies are the most obvious candidate for this type of application, they are not the only ones. For instance, balance testing can be used to monitor the progress of patients who suffered from traumatic brain injuries or mild traumatic brain injuries, especially

athletes, to see when they have recuperated enough to resume their normal activities (we depend on it in the management of concussions, especially sports related ones). We embrace the concept that if a patient’s neurological picture or health status is improving, there should be an associated improvement in the balance and postural stability, at least as a trend (time localized factors could make the results fluctuate because a person never recovers in a straight and linear way, but rather with ups and downs).

Using the CAPS™ to Prevent Falls Because balance can change very rapidly, for preventing falls it is important to monitor a person's balance as frequently as possible, sometimes even several times a day. It is unrealistic to expect that a balance test or any other fall risk assessment will predict the occurrence of falls weeks or months in advance. Sometimes the loss of balance that leads to a fall is a temporary event that quickly disappears. For instance blood pressure can change significantly during the day for various reasons, leading to periods of time when the pressure is low enough that the person is actually experiencing a presyncope. Similarly, the effects of medications or changes in the blood sugar level can lead to periods of critically reduced ability to maintain balance. Therefore, it is necessary to test balance often to see if these temporary events occur. The health status of a person can also change, for instance because of the onset of a cold or influenza. An elderly person might also suffer transient ischemic attacks. Their balance might be sufficient to avoid a fall one day and worsen the next, and the only way to detect this is by frequent testing.

The Use of Computerized Dynamic Posturography …

Using the CAPS™ to Educate about Balance Ultimately, to use balance as an indicator of general heath, to prevent injuries caused by the loss of balance, and to maintain good balancing abilities all life long, it is necessary that the public be educated and aware of the issues related to balance. Being able to show the changes that occur in the ability to maintain balance can be a way to educate the general population about these issues that is more effective than simply talking about them because it provides concrete examples. We find that the Computerized Dynamic Posturography tests promote our ability to educate the public and we have several large investigations in this area in a proposal stage.

Economic Considerations of Using the CAPS™ Our primary focus is our service to humankind. In order to serve we need to be realistic and deal with the economic realities. This includes considering the direct and indirect costs and benefits of devices like the CAPS™. We have looked at many operational models in order to serve a patient base that is referred to us from around the globe. For considering the direct costs, we compare the expenses of evaluating a person's balance using traditional observation based assessments with the expenses of using the CAPS™. Typically, traditional observation based assessments (such as the Berg Balance Scale, the Tinetti Balance Test of the Performance-Oriented Assessment of Mobility Problems, or the Balance Error Scoring System) take about 15 minutes.

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With the CAPS™ an evaluation can be performed in less than 1 minute and a full mCTSIB testing battery takes less than 3 minutes. We have calculated that for every traditional observation based assessment, at least 5 CAPS™ evaluations can be performed, thus allowing us to attend to a larger patient base with a greater impact of our service. The indirect considerations are associated with the worth of detection of more balance dysfunctions and being able to prevent falls and improve the health and function of many subjects in a superior fashion. Patients appreciate the test and have evidence of pathology and of improvement or decline. This is associated with a higher patient satisfaction, better outcomes, and reduced costs for unnecessary tests. Our clinicians appreciate having objective documentation of a patient's progress and justification for vestibular testing and rehabilitation.

Recommendations We recommend the use of Computerized Dynamic Posturography in all patients seen in the Functional Neurology Clinic. We have found this technology instrumental in allowing us to identify functional pathology and measuring the outcomes of many different modalities of treatment. We have found it both an education tool for patients and physicians and regard it as an integral modality in all of our diagnostic and therapeutic applications.

References [1]

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Receievd: 5 May 2012 Revised: 16 June 2012 Accepted: June 27 2012



Restoring of Brain Entropy and Complexity after Rehabilitation of Traumatic Brain Injury Nazareth P. Castellanos1, Elisa Rodríguez-Toscano1, Javier García-Pacios1, Pilar Garcés1, Nuria Paúl2, Pablo Cuesta1, Ricardo Bajo1, Juan García-Prieto1, Francisco del-Pozo1, and Fernando Maestú1,3 1

Laboratory of Cognitive and Computational Neuroscience (Centre of Magnetoencephalography) Centre of Biomedical Technology (CBT). Universdiad Politécnica de Madrid, Spain 2 Department of Basic Psychology I – Basic Process, Universidad Complutense de Madrid, Madrid, Spain 3 Department of Basic Psychology II – Cognitive Process, Universidad Complutense de Madrid, Madrid, Spain

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Correspondence: Dr. Nazareth P. Castellanos Laboratory of Cognitive and Computational Neuroscience, Centre for Biomedical Technology, Campus de Montegancedo 28660, Universidad Politécnica de Madrid, Spain. Email: [email protected]

Abstract Brain plasticity is understood as the capacity of the brain to evolve, or recover after an aggression. Even in the adult brain, plasticity plays an important role in functional recovery after acquired brain injury, which might have significant relevance to the practice of neurorehabilitation. It is of special interest to identify the mechanisms underlying plasticity for functional improvement after injury. A very appropriate platform to study the principles followed by brain plasticity is the study of brain activity changes after brain injury and posterior recovery. To reach this goal we analyzed the magnetoencephalographic recordings from 15 traumatic brain injured patients before and after neuropsychological rehabilitation and 14 healthy controls, in resting state condition. We compared the entropy and complexity in these three conditions to estimate how the brain injury impact alters the dynamical pattern of the brain activity. After traumatic brain injury the brain is globally more complex and entropic, principally in frontal and occipital areas. These values were restored after rehabilitation, statistically approaching to the healthy control reference. Change in patient complexity negatively correlates with PCRS, reflecting the patient’s current ability to adapt to daily living activities. The characterization of neuro

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Nazareth P. Castellanos, Elisa Rodríguez-Toscano, Javier García-Pacios et al. physiological changes would allow us to know the mechanism of recovery and the possible identification of recovery markers.

Keywords: Traumatic brain injury, Neuro-rehabilitation, Plasticity, Magneto-encephalography (MEG), entropy, complexity.

Introduction Traumatic brain injury (TBI) is one of the most common causes of disability in the world. After TBI, the impairment in essential functions for routine activities, such as movement programming and execution, sensorimotor integration, language and other cognitive functions have a deep and life-long impact on life's quality. The brain’s capacity to recover and adapt to new environments, which is called neuroplasticity or brain plasticity, is also a crucial neurophysiological mechanism after brain lesions. Growing evidence shows that the brain is capable of significant spontaneous functional recovery after brain injury due to plastic mechanisms that can be enhanced by the use of therapies. In order to treat cognitive deficits, neuropsychological rehabilitation has been developed as a systematic, functionally oriented therapeutic intervention, based on: the assessment and understanding of patient’s cognitive deficits, emotional or behavioural regulation problems and functional disabilities. The term “Neuropsychological Rehabilitation” can be applied to any intervention, programme or technique carried out with the purpose of enabling people and their relatives to live with, manage, by-pass, reduce or come to terms with cognitive deficits caused by a neurological alteration or disease [1]. Therefore, the practice of this discipline is not only concerned with cognitive deficits of these patients but also

with emotional, behavioral and psychosocial consequences of their condition, as well as the impact of this condition on family members, attempting to provide them with tools that achieve the best possible quality of life. Currently, it is possible to find a large amount of literature supporting the benefits of various types of cognitive interventions with traumatic brain injury patients [2-6]. Nevertheless, the scientific study of the effectiveness of rehabilitation is limited not only by the heterogeneity of subjects and interventions, but also by the ethical principles that guide its practice, as well as the different measures of outcomes available and the varied methodologies used for this purpose. A common measure of treatment effectiveness refers to changes observed on psychometric tests of cognitive function, before and after the rehabilitation process [7]. This method is mainly used in clinical settings by neuropsychologists and corresponds to what Carney and colleagues [8] call “indirect evidence” of effectiveness, while measures of employment and real-life function are considered “direct evidence”. Within the latter, there is a wide range of tools for evaluating outcomes (e.g. Glasgow Outcome Scale (GOS), the Disability Rating Scale (DRS), Functional Independence Measure (FIM), the Functional Assessment Measure (FAM) or the Barthel Index) as well as a lack of consensus about the most appropriated ones for scientific purposes. Notwithstanding, the mechanisms that take place within the brain during the rehabilitation process and the way in which cortical reorganization occurs have not been completely unveiled yet, although the increased use of functional neuroimaging methods is enhancing our understanding of brain damage and neuronal plasticity [9]. Research has shown that practice and experience can produce changes in the organization of the cerebral cortex as well as some evidence about neuronal

Complexity in Brain Activity after the Recovery of Traumatic Brain Injury reorganization following rehabilitation have already been provided. Some of these studies have found a decrease of activation in specific brain regions associated with better functional recovery outcomes, such as the activation pattern became similar to ones observed in normal subjects [for reviews, see 10,11]. In contrast, other studies have reported an increase in the activation pattern after rehabilitation, especially in contralesional areas. On the other hand, a combination of increases and decreases has been also observed, either reflecting a quantitative change in the pattern of activation within the same areas,redistribution of functional activations-, or a qualitative reorganization to different cortical areas, -“process switching”- [12]. Considering that cognitive processes require a functional interaction between specialized multiple, local and remote brain regions, a new approach has been used based on the idea that these interactions can be strongly altered in brain injury. Very recently, in Castellanos and her colleagues [13, 14] evaluated the impact of brain injury on functional connectivity patterns, showing a correlation between changes in the brain functional connections and the neuropsychological improvement of the patients after rehabilitation. We showed that the functional connectivity pattern was restored to healthy-control ones after recovery, specifically in delta and alpha bands, and we designed a model that could give some hints about how the functional networks modify their weights in the recovery process. These results might indicate that the structure of the functional networks evolves in parallel to brain recovery with correlations with neuropsychological scales. Functional connectivity, which can be estimated from non-invasive techniques as MEG or EEG, refers to the functional association between recording brain sites

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[15,16]. However, due to technical limitations we cannot easily infer in the local underlying synchronization of the brain activity recorded with a scalp-sensor. Indirect measures of such synchronization could reflect the dynamic properties of the brain activity and its alteration due to brain injury. Very recently used measures to characterize brain signals are the complexity and the entropy. The definition of complexity is still today a matter of debate in the scientific community [17]. Formally, complexity is defined as “the state of being formed of many parts; the state of being difficult to understand.” But intuitively we could define complexity as a measure which increases when the variety (distinction) of components increases, and it is directly related to the dependency (connection) of parts. For example Tononi et al. [18] proposed a measure, called ‘neural complexity (CN)’, which can be defined as a balance between functional segregation and integration in the brain. The majority of these measures can be defined as an estimate of the regularity/variability of brain oscillations and an attempt to evaluate the number of independent oscillators or frequency components underlying the observed signal (Figure 1). Therefore, the higher the level of complexity, the more components oscillating independently, with lower degree of communication between one another. Complexity is determined in several dimensions, as the three spatial dimensions, geometrical structure, spatial scale, time and dynamical scale [17]. Nowadays, complexity is receiving a growing interest in different scientific fields [19,20], as for example in the field of signal processing [21] and dynamical systems, where several measures of complexity are available (Hausdorff dimension to Lyapunov exponent, and Kolmogorov-Smirnov entropy). (For a comparison of different

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measures in the Neuroscience (multichannel EEG) see [23]). In this work we aim to study for first time how complexity and entropy of brain activity change as a consequence of traumatic brain injury. To this end, we estimated entropy and complexity of MEG signals from a TBI patients group, before and after cognitive treatment, and from an age-matched healthy controls group, in resting state condition. With the following hypothesis: 1) If complexity values increase with disintegration of the global network, patients before cognitive rehabilitation will show

higher levels of complexity than healthy volunteers; 2) if cognitive rehabilitation affects the functional brain network, in accordance with previous studies [13,14], complexity values in patients after rehabilitation will be lower than before rehabilitation. Moreover, cognitive rehabilitation will approximate patients’ complexity values to those showed by healthy controls; and 3) changes in complexity due to cognitive rehabilitation will correlate with improvement in measures of daily living competency.

Figure 1. Complexity can be defined as the number of independent oscillatory components in the brain signal (measured by scalp recording sites). The lack of synchronization between components produces an increase of complexity.

Materials and Methods Patients and Rehabilitation 29 adults took part in the experiment: 15 traumatic brain injured (TBI) patients and 14 healthy controls. All TBI patients were

included in a neurorehabilitation program (mean age 32.13 years; age range, 18 to 51 years; mean level of education, 13.7 years; range, 8 to 18 years; mean time since stroke, 3.8 months; range, 2 to 6 months; neurorehabilitation program period, 9.4 months; range, 7 to 12 months; Table 1).

Complexity in Brain Activity after the Recovery of Traumatic Brain Injury All TBI patients showed severe cognitive impairments in several domains such as attention, memory and executive functions. Experimental and healthy control groups were matched for age (31.93), educational level (15.57) and gender. None of them had previous history of psychiatric disease or extended psychoactive drug consumption. We took MEG recordings and neuropsychological assessments before (“pre”) and after (“post”) neuropsychological rehabilitation program. However, control subjects were measured once, assuming that brain networks do not change in their structure in less than one year, as demonstrated previously in young [23] and elderly subjects [24]. Informed consent was obtained from each subject or a legal representative after full explanation of the study. The Research Local Ethics Committee approved the study. Neuropsychological assessment of both groups included a number of standardized test and functional scales in order to provide their cognitive and functional status concerning attention skills, memory processes, language, executive functions, visuospatial abilities and some daily activities. The subjects of experimental group received individual neuropsychological treatment during 1 hour, for 3-4 times per week. In some cases, cognitive intervention was coupled with other types of neurorehabilitation therapies according to the patient´s profile (physiotherapy, speech therapy or occupational therapy). For more detailed description see [13].

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MEG and Data Preprocessing Cortical magnetic signals were recorded with a 148-channel whole-head magnetometer (4D-MAGNES 2500 WH, 4-D Neuroimaging) confined in a magnetically shielded room. The recording was bandpass filtered between 0.1 and 50 Hz and raw data were submitted to a noise reduction procedure. Magnetic fields were measured during resting state with openedeyes condition, at a sampling rate of 169.45 Hz. Time-segments containing eye movements, blinks, other myogenic or mechanical artiefacts were visually rejected by experienced investigators, reaching to 12s length segments. Digitized MEG data were imported into MATLAB Version 9.1 (Mathworks, Natick, MA, USA) for analysis with custom-written scripts.

Entropy, Complexity (SMC index) and Statistics Entropy can be defined as the average amount of code necessary to encode the draws of a discrete variable X with M possible outcomes Xi, each of them with probability pi. The Shannon entropy [25] of this set of probabilities is:

This entropy is positive and is measured in bits (when log 2 base is used). Entropy can be interpreted as a measure of the uncertainty of the outcome. Thus the largest entropy corresponds to a uniform distribution in which all the states have the same probability, while a peaked delta distribution will have minimum entropy. Complexity measures are mostly based on

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either information from theoretic approaches (i.e. in terms of entropy and predictability) or on topological properties (i.e. correlation or fractal dimension). We complementarily use SMC (signal mode complexity) [26] as a measure aimed at assessing the complexity of a time series, based on the distribution of the strengths of its orthogonal oscillatory modes and it is based on singular value decomposition. SMC does not require any prior assumption on the nature (such as determinism or nonlinearity) of the analyzed time series, and is completely data-adaptive. After scaling, the averaged singular value profile is able to distinguish chaotic from random structure in a time series. The complexity index is calculated as the weighted mean average of this averaged singular value profile, where a weight inversely proportional to the singular value dominance is applied. A non-parametric Kruskall-Wallis test (p