IEEE- Fourth International Conference on Advanced Advanced Computing, Computing, ICoAC 2012 13-15, 2012 MIT, Anna University, Chennai. December 13-15,
Immersive Virtual Reality for Pain Distraction Methodologies and Barriers
S.Sridevi Anna University, Guindy Campus Chennai, India
[email protected]
Abstract - A novel method for managing and treating physical It has been hypothesized that the ideal distractor would and psychological pain is the need of the hour. Although require an optimal amount of attention, involving multiple cybertherapy is at its development stage, a great potential can be sensory modalities (visual, auditory, and kinesthetic), active reaped when it is moulded in the right way. Clinical virtual emotional involvement and participation of the patient to reality is found to be a promising way of distracting the patients compete with the signals from the noxious stimuli. from sensing the pain during medical procedures, physical rehabilitation or post-traumatic stress. There exists no single II. HISTORY OF PAIN & CYBER THERAPY pain management methodology that is good for everyone, or even Before the relatively recent discovery of neurons and their the majority of people. Research findings prove that pain has many causes and courses, and can impact individuals in a role in pain, various different body functions were proposed to multitude of ways including the behavioral, physiological, account for pain. There were several competing early theories emotional, psychological, social and spiritual levels. Though of pain among the ancient Greeks: Aristotle believed that pain distraction through audio visual aids has a significant effect in was due to evil spirits entering the body through injury, and decreasing the intensity of pain signals in the brain, the analgesic Hippocrates believed that it was due to an imbalance in vital efficacy has to be well researched and improved. The perception fluids. In the 11th century, Avicenna theorized that there were of pain varies with factors such as age, ethnicity, sex and genetics. a number of feeling senses including touch, pain and titillation, Increased nervousness of patients in virtual world, patients’ but prior to the scientific Renaissance in Europe pain was not confidentiality, subjectivity in effectiveness on individuals, array well understood, and it was thought that pain originated outside of pains to be handled with a single virtual platform and cost are 978-1-4673-5584-1/12/$31.00©2012 the major barriers to be tackled. This paper discusses ways of the body, perhaps as IEEE a punishment from God. [3] providing such generic, acceptable and proven methods of In 1644, René Descartes theorized that pain was a cybertherapy. Such virtually painless world shall be greatly disturbance that passed down along nerve fibers until the achieved only with close cooperation between technologists and disturbance reached the brain, a development that transformed medical experts. Index Terms - virtual reality, cybertherapy, pain management, distraction technique
I. INTRODUCTION Over a decade distraction has been investigated and successfully applied in clinical practice to reduce pain associated with medical procedures. Successful traditional distraction techniques are e.g., watching movies, listening to music, counting objects in the room, and nonmedical conversation. The application of distraction is based on the assumption that pain perception has a large psychological component in that the amount of attention directed to the noxious stimuli modulates the perceived pain. [1] Distraction techniques tax the patient’s limited attention capacity, resulting in the withdrawal of attention away from the noxious stimulus. Although the precise mechanism of distraction is not yet well understood, cognitive-affective attention models according to which incoming nociceptive signals can be modulated at the upper spinal cord, as explained in Melzack’s gate-theory. [2]
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the perception of pain from a spiritual, mystical experience to a physical, mechanical sensation. Descartes's work, along with Avicenna's, prefigured the 19th-century development of specificity theory. Specificity theory saw pain as "a specific sensation, with its own sensory apparatus independent of touch and other senses". A breakthrough 20th-century theory was "gate control" theory, introduced by Ronald Melzack and Patrick Wall in the 1965 Science article "Pain Mechanisms: A New Theory". The authors proposed that both thin (pain) and large diameter (touch, pressure, vibration) nerve fibers carry information from the site of injury to two destinations in the dorsal horn of the spinal cord, and that the more large fiber activity relative to thin fiber activity at the inhibitory cell, the less pain is felt. [2] To explain why thoughts and emotions influence pain perception, Ronald Melzack and Patrick Wall proposed that a gating mechanism exists within the dorsal horn of the spinal cord. Small nerve fibers (pain receptors) and large nerve fibers ("normal" receptors) synapse on projection cells (P), which goes up the spinothalamic tract to the brain, and inhibitory interneurons (I) within the dorsal horn.
IEEE-ICoAC 2012 2012 IEEE-ICoAC III. RESEARCH STUDIES Table 1 summarizes a sample of the research studies indicating sample characteristics, methodology, equipment specifications, and the results. The studies are arranged by patient population and if applicable, additionally categorized in Virtual Reality (VR) or Audio/Video (A/V) distraction respectively, to allow easy comparison between both methods. VR was performed with burn patients (N = 23), dental patients (N = 1), cancer patients undergoing subcutaneous venous port access (N = 2), a patient with cerebral palsy participating in a physiotherapy program following Single Event Multi-Level Surgery (N =1) and with healthy volunteers in a laboratory setting where pain was induced by a tourniquet (N = 1). A/V distraction has been studied in patients undergoing gastric laboratory procedures (N = 2), leg ulcer patients (N = 1), cancer patients undergoing lumbar punctures (N = 1) and dental patients (N = 3). Additionally, there are three reports of testing A/V distraction in the laboratory using a cold pressure test or a tourniquet. TABLE I. Medical Procedure Burn patients undergoing wound debridement
Patients undergoing laboratory gastric procedures
Study Participants 23
87
Fig. 1. Melzack - Wall: Gate Control Theory.
The Gate Control theory suggests that the interplay among the nerve fibers and neurons determines when painful stimulus goes to the brain. As shown in Fig.1 (a), when no input comes in, the inhibitory neuron prevents the projection neuron from sending signals to the brain and the gate is closed. Normal somatosensory input happens when there is more large-fiber stimulation. Both the inhibitory neuron and the projection neuron are stimulated, but the inhibitory neuron prevents the projection neuron from sending signals to the brain and the gate is closed as shown in Fig.1 (b). As in Fig.1 (c), Nociception (pain reception) happens when there is more small-fiber stimulation or only small-fiber stimulation. This inactivates the inhibitory neuron, and the projection neuron sends signals to the brain informing it of pain (i.e.) the gate is open. In 1999, on surveying the current state of virtual reality applications, Fred Brooks [10] could find only seven categories of verifiable production applications of VR such as: Vehicle simulation, entertainment, vehicle design, architectural design and spatial arrangement, training (only at NASA), psychological treatment, probe microscopy. [11] Now, if we analyze the VR application domains, we could find a great deal of potential in it.
Patients undergoing dental treatments
EXPERIMENTAL R ESULTS
46
VR Equipments Used HMD, Motion sensing system, Sound effects, Spider World
LCD glasses with audio travelogue through virtual land HMD, SnowWorld
Results Pain Measures Nausea nonexistent. Presence of object realism 82%VR preference tolerance Pain Measures Presence of object realism
Patients undergoing lumbar puncture
30
LCD glasses, A/V with skiing, dancing and racing
90% wanted to use VR next time
IV. RESEARCH INFERENCES Table 1 shows that sample sizes range from one to 72 participants, 35% of the studies have samples of less than 10 subjects and the average sample size is 23.35 subjects (SD = 20.76, median = 23.50). A total of 467 patients have been studied; 108 patients were exposed to VR and the remaining 359 used A/V VR and A/V Distraction. All but one study included a control condition, either including a within subjects (randomized order of condition) or between-subjects (randomized allocation to conditions) design. [1] In all ten studies that applied VR, it proved effective in most if not all patients, while in all but three studies using A/V distraction, a significant analgesic effect was found compared to the control condition.
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Fig. 2. Patient undergoing VR therapy using Head Mounted Displays[6]
In some A/V distraction studies patients were asked whether they would like to use the eyeglasses during future treatments. Patients generally indicated to prefer future treatment with the eyeglasses, with percentages ranging from 79% to 100%. Except for the VR case study by Gershon et al. [8] in which anxiety increased, anxiety ratings did not change or decreased during exposure. Remarkably, the studies showing no change in anxiety all used VR. Finally, the studies that also included nausea ratings demonstrated that this side effect was negligible to non-existent. The aim of the research experiment was to provide an overview and critical evaluation of the current use of VR and A/V distraction as adjunct analgesic techniques during painful medical procedures. To achieve the aim three questions were formulated to answer after experimenting with few patients exposed to VR as shown in Fig.2. The first question consisted of two parts: first we asked if VR and A/V distraction are effective analgesic techniques and if so, whether the analgesic effect is clinically relevant; second, whether these types of distraction are applicable in a wide range of medical problems and procedures. The results of the included studies strongly suggest that both VR and A/V distraction may indeed significantly reduce pain associated with a multitude of medical interventions. The induced analgesia was in almost all cases clinically relevant, both for VR and the less sophisticated A/V techniques. Especially patients who reported very high to unbearable pain levels appeared to benefit greatly. Given the promising results of these studies, further exploration of this application using more appropriately designed studies is highly recommended. [1] The pain scores before and after VR are tabulated below:
TABLE II.
PAIN SCORES WITH AND WITHOUT VR
The unit of pain is del. Pain scores in the table proves that the pain felt when exposed to VR is commendably lesser than without VR. The pain tolerance with VR is high. Another research study on effectiveness of VR in physical therapy shows several more potentials that can be tapped from VR. Successful participation in physical therapy after a severe burn injury is often crucial for minimizing long-term disability. Without physical therapy, the normal healing process in severely burned and grafted skin results in heterotopic scarring, and severe contractures. Aggressive physical therapy increases the flexibility/elasticity of healing skin, and helps maintain normal range of motion and function. Unfortunately, the pain experienced during therapeutic movement of burned, grafted, and healing extremities can discourage patients from performing their exercises. Patient non-adherence to such exercises can lead to additional surgery (e.g., more skin grafts) or permanent reduction in limb mobility. Opioid analgesics have long been considered the “gold standard” of pharmacologic analgesics. Although such drugs form the cornerstone for nearly any burn pain management plan, side effects limit their use (e.g., nausea, vomiting, constipation, sedation, itchiness, urinary retention, cognitive impairment, hallucinations, delirium, respiratory depression, tolerance, and risks for physical and psychological dependence). [4] These side effects can become especially problematic when opioid analgesics are administered over prolonged periods. Additional concerns about opioid analgesics is that, even though they represent the best approach to burn pain, and are highly effective for treating background pain, their analgesic efficacy for extreme procedural pain is limited. Patients with severe burns routinely experience severe pain during wound care, despite aggressive pain control with potent opioid analgesics. In one study of patients with severe burns, 84% of the patients given a typical dose of morphine still reported severe to excruciating pain during wound care. Two thirds of the burn patients in that study rated their worst pain during wound care as “excruciating”. As a result of the strong psychological component to pain perception, supplemental use of non-pharmacologic analgesic techniques can be effective, e.g., mental imagery, watching a video, biofeedback, enhanced control, parental participation and hypnosis. Cognitive/behavioral strategies have been found to be useful for a wide variety of pain etiologies, and significantly reduced pain reports in 85% of 47 studies (metaanalysis). Distraction is a cognitive-behavioral intervention particularly useful with burn pain. Immersive virtual reality is an attention-grabbing illusory reality created in the mind of the VR user/patient. Researchers argue that virtual reality (VR) may be an unusually effective distraction. Performing a virtual reality task draws heavily upon conscious attention leaving less of this cognitive resource to devote to pain perception. With less attention available for evaluating nociceptive input, patients subjectively experience less pain. The convergence of multisensory input (sight, sound, and sometimes touch) in the virtual environment creates a sense of "presence" in the environment (i.e., the illusion of going into the computer generated world).
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Fig. 3. VR during staple removal [6]
In this respect, immersive VR differs from more simple forms of distraction by increasing the amount of the patient’s attention drawn into the virtual environment. A second mechanism by which VR may improve analgesia is through the reduction of visual cues associated with the painful procedure. Children often develop strong conditioned anxiety responses to visual cues associated with their wound care or rehabilitation procedure. Anxiety-inducing sights and sounds of the hospital or clinic environment that likely exacerbate the patient’s pain are blocked out by the VR helmet worn by patients during the procedure, thereby limiting these negative cues and aversive conditioning. Although the majority of patients fixate most of their attention on the wound care during conventional treatment, previous studies suggest that patients are able to shift their attention away from their pain with VR. Researchers measured the pain levels of two pre-adult patients undergoing staple removal from skin grafts while being distracted by VR for three minutes and staple removal while playing Nintendo64 for three minutes during a single wound care session as shown in Fig.3. Patients showed the predicted drop in pain when in VR compared to the video game condition. More recently, researchers conducted a within subject clinical study with twelve burn patients during physical therapy. All patients reported experiencing less pain in virtual reality compared to no distraction during a single physical therapy session, and the magnitude of pain reduction from VR was statistically significant. Patients also reported large reductions in the amount of time they spent thinking about their pain during the three-minute sessions (e.g., on a 100 mm scale, “time spent thinking about pain” during physical therapy dropped from 60 mm with no VR to 14 mm with VR). The average sized burn requiring inpatient hospitalization might require at least a week of hospitalization and numerous wound care and exercise sessions. In the case of an extremely severe burn, physical therapy sessions may take place over a
period of months and number in the hundreds. In all multiparticipant studies to date, each participant used VR only one time. If the analgesic effects of VR stem primarily from the novelty of this technological approach, pain control would likely become less effective with repeated use. VR pain control would be of limited value if it only worked the first time it was applied. [5] Encouragingly, in a recent pilot case study on a single burn patient, the amount of VR-based pain reduction did not diminish with repeated treatments over a one-week period. The present study further addresses this issue. Using a within subjects design, the efficacy of immersive virtual reality to a no distraction condition (conventional treatment) during at least three separate therapy sessions with multiple patients were compared. It can be hypothesized that, • VR would result in less pain, and less time thinking about pain than equivalent periods of physical therapy using a standard treatment protocol (no distraction), and • The amount of pain reduction would not decrease with repeated use. V. METHODOLOGIES IN PRACTICE Some of the Clinical VR techniques use only visual stimuli, but the majority applies visual stimuli in combination with audio stimulation and distracts the patient by exposing him/her to 2-D or 3-D videos. These techniques are referred to as VR audiovisual systems, A/V eyeglass systems or simply A/V distraction. The equipment used for this usually consists of modified glasses that incorporate small liquid crystal displays (LCDs) with or without earphones which VR and A/V Distraction are connected to an interface module that transmits optical (and auditory) signals (as e.g., Virtual Vision (VV) or IGlasses).However, these A/V distraction techniques do not allow any interaction between the users and the stimuli they are exposed to and also no use is made of kinesthetic stimuli.
Fig. 4. An Image from SnowWorld
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Fig. 5. An image of flying planes in the virtual world [6]
The most recent and most advanced distraction technique is VR, which makes up for this lack of interaction and kinesthetic stimulation. VR refers to a human-computer interface that enables the user to interact dynamically with the computergenerated environment. In contrast to the less complex A/V distraction, VR uses sophisticated systems such as head mounted, wide field-of-view, 3-D displays (HMDs) and motion sensing systems that measure the user’s head and hand position. These enable users to interact with the virtual environment (VE). The stimuli used for VR and A/V distraction range from simple entertaining fantasy worlds, Nintendo games and special 2-D or 3-D videos to simulated 3-D "virtual" real life situations with high ecological validity (for VR). Users can choose to explore in snow world (Fig. 4), fly planes (Fig. 5), drive cars, ski down mountaintops, and explore houses and much more.
The novel idea is that rather than allowing the patient to immerse in VR all alone and doing the medical procedures, there should be a way in which the therapist can support and monitor the patients in the virtual world through a communication channel. The virtual environment is controlled and supported by the therapist so that unnecessary nervousness and patient’s reluctance to undergo such VR shall be avoided. Such a system shall have the overall design as shown in Fig.6. The system has two major interfaces, one for the patient to operate in the virtual world and one for the therapist to view and monitor the patient’s activities in the real world. With such high end capabilities and support, good amount of analgesic efficacy can be assured from immersive VR procedures. The Collaborative Virtual Environment is one aspect that can reduce the nervousness of patients while undergoing VR enabled treatments. As shown in Fig.7, the overall layout of the virtual environment shall consist of the therapist interacting virtually with the patient which encourages the patient to be more interactive and engrossed in the virtual world. The client’s user interface components can be Head Mounted Displays (HMD) and joysticks. The therapist and the patient share the virtual world space and interact here through data sharing components as shown in Fig. 6. A common communication channel is required to reflect changes in the virtual world as per patient and therapist’s interactions. The therapist shall use web camera and space mouse to interact and monitor the environment.
VI. BARRIERS Though VR is proven to be of good analgesic efficacy, is has its own shortfalls that are to be overcome. The virtual platform has to be generic enough to treat various pains and each person has his/her own perception of pain. [7] The individuals have to be well informed about virtual reality platform before undergoing any medical procedure under immersive VR. If not, there may be increased nervousness for the patient due to entering into a virtual world. The patient may have any other disability such as visual/hearing impairment or immobility etc., Hence the virtual platform should support the varied group of patients who use it. VII. VIRTUAL MONITORING METHODOLOGY To overcome the various barriers, a good understanding of human perception about pain and how it is transmitted by the nerves is necessary. The proposed system consists of several modules which interact and communicate to produce required VR. The various modules are Common Communication channel, Audio/Video Interactions, Client’s User Interface module, Remote PC, Joystick, HMDs, Monitor and headphones for the therapist.
Fig. 6. Proposed system outline
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Fig. 7 Collaborative Virtual Environment
Another critical area of consideration is how virtual reality can be experienced by patients who are visually/hearing impaired. Here comes the touch and feel aspect of virtual environment. Such patients can be allowed to experience virtual environment through haptic sensors and interfaces. Haptic technology, or haptics, is a tactile feedback technology which takes advantage of the sense of touch by applying forces, vibrations, or motions to the user. This mechanical stimulation can be used to assist in the creation of virtual objects in a computer simulation, to control such virtual objects, and to enhance the remote control of machines and devices. It has been described as "doing for the sense of touch what computer graphics does for vision". Haptic devices may incorporate tactile sensors that measure forces exerted by the user on the interface. Hence special patients are to be exposed to virtual world through touch and feel sensors and actuators. Using haptic interface, users are able to feel the size and shape of computer-generated 3D objects in a simulated virtual world. Fig.8 shows a CyberGrasp interface wherein the user who is fitted with the electronic smart glove can feel and interact with objects in the virtual world. The CyberGrasp interface is of high efficacy in terms of experiencing the virtual world and getting immersed into it.
Virtual Reality can be implemented by utilizing Virtual Reality Modeling Language (VRML) and also the APIs present in Java. The Virtual Reality Modeling Language (VRML) is a file format for describing interactive 3D objects and worlds. VRML is designed to be used on the Internet, intranets, and local client systems. VRML is also intended to be a universal interchange format for integrated 3D graphics and multimedia. VRML may be used in a variety of application areas such as engineering and scientific visualization, multimedia presentations, entertainment and educational titles, web pages, and shared virtual worlds. Programming VRML with java can be done in 3 ways. They are VRML script node, VRML External Authoring Interface (EAI) and VRML implemented (in whole or in part) within another programming environment. Other options for creating Virtual worlds are OpenGL + C + VR Library, OpenPerformer (visual simulation scene graph library) + C++, YG (scripting language built on top of Performer), Java3D - with many custom extensions (U. of Calgary) The Points of Space (POS) are the several points in the virtual world which are to be specified with the necessary triggers that are to be invoked when those points are accessed by the patients who are immersed in the virtual world. The therapist shall be able to create scenarios in the virtual world which are given in response to the patient’s interactions. A multi-modal VR environment is one that includes audio, video and also a haptic interface. Such a multi-modal VR environment shall be one of the promising interfaces to achieve a virtually painless world. VIII. CONCLUSION AND FUTURE WORK Immersive VR, its potential, various methods with which pain distraction can be achieved through VR and its shortcomings is discussed in great detail. Immersive VR has to be provided in low costs with higher benefits. The ways of providing generic VR platforms with tools and options to explore in various situations of medical treatments are to be found. Future research is necessary to establish the optimal selection of clinical patients appropriate for VR pain therapy and the type of software required according to age, gender, personality, and cultural factors. A great amount of cooperation between physiologists, psychologists and technologists has to be brought together to overcome these several barriers. ACKNOWLEDGMENT I acknowledge and thank my mother and grandmother for supporting me in all aspects to complete my work successfully. I am grateful to everyone who inspires and encourages me to achieve great heights. I thank all my teachers and professors for their overwhelming support.
Fig. 8 CyberGrasp - Haptic Technology
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[7] Florella Magora, Sarale Cohen, Mara Shochina and Ehud Dayan, “Virtual Reality Immersion Method of Distraction to Control Experimental Ischemic Pain”, IMAJ, Vol 8, April 2006. [8] Gershon, J., Zimand, E., Pickering, M., Lemos, R., Rothbaum, B., & Hodges, L. “Use of virtual reality as a distractor for painful procedures in a patient with pediatric cancer: A case study. Cyberpsychology & Behavior, 6, 657-661. [9] Torres-Gil, M. A., Casanova-Gonzalez, O., Gonzalez-Mora, J. L., “Applications of Virtual Reality for Visually Impaired People,” WSEAS transactions on computers, Issue 2, Volume 9, February 2010. [10] F.P. Brooks, Jr., “What’s Real About Virtual Reality?,” IEEE Computer Graphics and Applications, vol. 19, no. 6, Nov./Dec. 1999, pp. 16-27. [11] Larry F. Hodges, et al. “Treating Psychological and Physical Disorders with VR”, IEEE Computer Graphics Association, 0272-1716/01, 2001.
