Proprioception interventions to improve cervical ...

Critical review

Critical review

Proprioception interventions to improve cervical position sense in cervical pathology Cheryl M Petersen, Chris L Zimmermann, Rong Tang Background: Non-specific cervical pain is a common pathology and is difficult to treat. Various types of treatment interventions have been used individually or in combination. Proprioception training has been suggested as an aspect of intervention for cervical pathology but no systematic review has been conducted to evaluate the effectiveness of cervical proprioception retraining on reposition sense. Methods: A systematic review of the literature was performed to evaluate the effectiveness of proprioception interventions to improve cervical position sense (PS) in patients with pathology. A modified American Academy of Cerebral Palsy and Developmental Medicine method was used to systematically grade the level of evidence. In addition, a meta-analysis was performed on the intervention effects on PS or pain. Findings: PS was measured in 11 studies; seven used a laser pointer while four used motion detection instrumentation. Various treatment interventions, including deep cervical flexor activation, eye-head neck coordination exercises, mobilisation, manipulation and a multi-behavioural exercise approach were used individually or in combination to affect proprioception. Pain was measured in six studies using various outcome measures. The meta-analyses showed high heterogeneity of results in favour of treatment interventions for flexion/extension and for right/left rotation to improve PS as well as for pain reduction for the pain outcome measures. Conclusions: All the treatment interventions activated proprioceptors through muscle activation and joint or skin sensory receptors. The use of eye-head-neck coordination exercises produced moderate and large treatment effects for improving PS. This type of exercise links the sensory/motor (proprioception) systems of the neck with the oculomotor and vestibular systems to improve PS. Pain was also reduced (moderate effect size) with the use of these techniques. Clinicians targeting improvements in cervical PS may use this evidence, but further research is needed. Key words: n position sense n pain n cervical n treatment intervention n level of evidence n meta-analysis Submitted 2 March 2009; accepted for publication following double-blind peer review 19 February 2013

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ervical pain has been reported to be one of the most common musculoskeletal disorders in adults, with an annual prevalence ranging from 12% to 71.5%, as well as in children and adolescents, where the annual prevalence ranges from 21% to 42%. In addition to affecting a patient’s quality of life, cervical pain can result in substantial socioeconomic burden in terms of loss of productivity and continuing associated financial costs (Humphreys and Irgens, 2002; Hogg-Johnson et al, 2009). Conditions such as neurological compromise, fracture, vascular disorders or inflammatory disease may be associated with cervical pain. However, in most cases, cervical pain is classified as non-specific as no certain cause can be found, which implicates structures such as muscle, ligaments, intervertebral discs, 154

zygapophyseal joints or neural structures in the problem. Non-specific cervical pain, therefore, is difficult to treat efficaciously (Leaver et al, 2010). Because all these structures contribute to proprioception, proprioception retraining has been suggested as a treatment intervention. Cervical function depends on multiple connections to the visual, vestibular and postural control systems. Reflex and central connections through receptors in the cervical muscles, especially the deep portions of the suboccipital muscles, provide these multiple connections. The cervical postural reflexes (vestibulocollic, cervicocollic, optokinetic and tonic neck) may be affected by cervical dysfunction, creating dysfunctional motor loops (Bolton, 1998; Dutia, 1989; Humphrey and Irgens, 2000). Gaze is affected by head position in space and eye orientation within the head. Three gaze

Cheryl M Petersen is Associate Professor, Concordia University Wisconsin, Mequon, US; Chris L Zimmermann is Practice Manager, Dermatology Clinic SC, Green Bay, Wisconsin, and was Associate Professor, Physical Therapy, Concordia University Wisconsin, at the time of this research, Mequon US; Rong Tang was doctoral student, Concordia University Wisconsin, Mequon, US, at the time of this research Correspondence to: Cheryl.Petersen@ cuw.edu

International Journal of Therapy and Rehabilitation, March 2013, Vol 20, No 3

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stabilisation reflexes are involved when head position changes occur. The vestibulocollic reflex (VCR) is of vestibular origin, and acts on neck muscles to move the head. Both the cervicocollic (CCR) and cervicoocular reflexes originate from receptors in the neck and act on cervical and extraocular muscles (Petersen et al, 1985). The CCR, like the stretch reflex, opposes the rotation of the head on the body through muscle spindle activity. Gaze stability is dependent on oculomotor reflexes from the vestibuloocular and optokinetic reflexes. The VCR, by decreasing the amount of head deviation, may assist in gaze stability. The VCR and CCR prevent head instability through the ability to reduce head rotation relative to the body. Programmes including eyehead coordination, the practice of relocation of the head on the trunk or gaze stability exercises target these reflex connections and the deep suboccipital muscles (Jull et al, 2007). Coupling between cervical muscle activity and gaze orientation has been found in humans (André-Deshays et al, 1988; 1991). Exercises based on eye-head coupling appear to be more appropriate than usual rehabilitation to facilitate cervical proprioception because they improve the coordination between the visual, vestibular and proprioception systems. Altered afferent information from the visual, vestibular and cervical proprioceptive afferents can produce a loss of coordination between the head, eyes and upper limb, affecting head orientation in space and relative to the trunk.

Pain treatments Various treatment interventions have been used individually and in combination to treat acute and long-term cervical pain. Many review studies have evaluated individual and combined treatment interventions. Strong evidence supports the use of muscle strengthening and endurance exercises to treat office workers’ cervical pain; moderate evidence has been found for muscle endurance exercise using deep cervical flexor activation (three sets of 20 repetitions, five times a week for 12 months) for reducing disability in office workers (Sihawong et al, 2010). Advice to rest is less effective than active treatment for whiplashassociated disorders, and evidence to support it is poor (Verhagen et al, 2007). A Cochrane review on acupuncture found moderate evidence for acupuncture compared to placebo for pain relief. Moderate evidence for pain relief was also found for at least six sessions of acupuncture versus a waiting-list control for cervical disorders with radicular symptoms (Trinh et al, 2010).

Mobilisation, manipulation and physical medicine modalities (exercise, electrotherapies and phototherapies) may affect analgesia and inflammation from a neurophysiologic approach or may produce permanent or short-term changes in connective tissue length from a mechanical perspective (D’Sylva et al, 2010; Gross et al, 2010). Cervical mobilisation or manipulation alone has been found to produce some immediate or short-term pain relief in acute and long-term cervical pain. Thoracic manipulation used alone or in conjunction with electrothermal or individualised physical therapy may improve function and pain in acute to long-term cervical pain (Gross et al, 2010). Manipulation and mobilisation both provide similar functional improvements, pain relief and patient satisfaction in acute and longterm cervical pain. No ideal dosages were determined for cervical mobilisation or manipulation but anterior-to-posterior mobilisation may be better than transverse or rotational techniques (Gross et al, 2010). Significant short-term alleviation of pain results from multimodal techniques, manipulation, specific exercise (programmes for specific impairments, such as posture training, head reposition accuracy, neck stabilisation, relaxation and eye fixation), manual therapy and a combination of orphenadrine/paracetamol medication (Leaver, 2010). In a systematic review with low-quality evidence, clinically important long-term positive change in function/disability, pain and global perceived effect (GPE) for subacute/long-term cervical pain with headache was found when exercise and manual therapy was compared to no treatment (Miller et al, 2010). For long-term cervical pain, moderate evidence for manual therapy has been found for improved quality of life and pain reduction, with greater short-term pain improvement compared to traditional care for acute whiplash injuries; low-quality evidence supports improvements in patient satisfaction and function (Miller et al, 2010). There is moderate evidence for mobilisation, manipulation and soft tissue mobilisation compared to short-wave diathermy for improved satisfaction and decreased pain for acute cervical pain; these three treatments, paired with exercise and advice, showed greater improvement in GPE and satisfaction than exercise and advice combined. A clinically important benefit was found for manipulation and mobilisation in improved function, pain relief and GPE in patients with chronic cervicogenic headache compared to controls at intermediate and long-term followup; however, the evidence was of a low quality (D’Sylva et al, 2010).


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Critical review A Cochrane review on exercise concluded there was strong evidence favouring a multimodal approach of exercise with mobilisation or manipulation in both the short and long term, benefiting subacute and long-term mechanical cervical disorders with or without headache. Moderate evidence for pain relief in long-term mechanical cervical disorders in both the short and long term was found for stretching and strengthening programmes. Eye fixation/proprioceptive exercises showed moderate evidence to support their use to manage chronic mechanical cervical pain in the short term for pain relief, and improved function and GPE, and in the long term for pain relief and improved function regarding either acute or subacute whiplash associated disorders with or without headache. Dosage parameters, specific exercise techniques or if certain subgroups benefited the greatest could not be determined (Kay et al, 2009). The multimodal approach using manual therapy treatment of cervical pain is supported by the above referenced reviews and requires further research regarding parameters of treatment and the best combinations for acute to chronic cervical pain.

Proprioception training As the literature says, the various interventions included in these reviews could be considered proprioceptive retraining. Proprioception is considered essential for the control of human movement and can be important in diagnosing motor control impairment (Lephart et al, 1997; Loudon et al, 1997; Heikkilä and Wenngren, 1998; Swinkels and Dolan, 1998). Proprioception describes sensations generated within the body that contribute to an awareness of the relative orientation of body parts, both at rest and in motion (Swinkels and Dolan, 1998). T h e p r o p r i o c e p t ive s y s t e m d e p e n d s upon simultaneous activity in a number of types of mechanoreceptor afferent neurons. Mechanoreceptors provide information for reflex regulation of muscle tone, awareness of position sense and movement sense (Gardner et al, 2000) and have been isolated in most spinal tissues (Amonoo-Kuofi, 1982; Yahia et al, 1988; 1992; Yamashita et al, 1990; 1993; McLain, 1994; McLain and Raiszadeh, 1995; Roberts et al, 1995). Afferent information is processed in the central nervous system (CNS) at both subconscious and conscious levels. The conscious component of proprioception can be measured through tests that assess either position sense (awareness of the relative orientation of body parts in space) 156

or movement sense (detection of movement and acceleration) (Swinkels and Dolan, 1998; 2000). Proprioception training has been suggested as an important aspect of treatment intervention in spinal pain rehabilitation (Revel et al, 1994; Jull et al, 2007; Roijezon et al, 2008). Few studies have measured proprioception while an intervention strategy is being carried out, which makes it difficult to determine if proprioception has been affected by the intervention. However, changes in proprioception have been suspected in clients with spinal pain, especially those with functional instability and consequently a predisposition for reinjury, degenerative joint disease and chronic pain (Hall et al, 1995; Rogers, 1997). Injuries interfere with the reflexes that depend on articular receptors between ligaments and muscles to protect against reinjury (Hall et al, 1995; Rogers 1997). However, a specific rehabilitation programme to improve spine proprioception has not been established. Little evidence supports the assumption that targeted exercise improves proprioception. Evidence regarding changes in the number of peripheral receptors associated with training is lacking. However, sensory input that affects proprioception and is processed by the CNS can be modified with training (Evarts, 1973; Brooks, 1983; 1986; Ashton-Miller et al, 1992; Schmidt and Lee, 2011).

STUDY AIM This investigation reviewed information regarding cervical spine reposition sense—an aspect of proprioception—its role relative to cervical spine pain, and the literature on spine reposition sense rehabilitation. The documented cervical proprioception training programmes have great diversity in terms of protocols, outcome measurements and methodologies undertaken. Clinicians are using what has been described in the literature as proprioceptive retraining programmes for patients with cervical involvement. The scientific evidence supporting proprioception retraining is lacking and no systematic review, to the authors’ knowledge, has been conducted to evaluate the effectiveness of cervical proprioception retraining on spine reposition sense. Second, the measurement of pain used by these studies evaluating proprioception was examined. The results of this review will allow clinicians to better evaluate the use of spine reposition sense in the care of patients with cervical spinal pain and provide suggestions for spine rehabilitation involving reposition sense.



Table 1. Internal validity grading Twelve-point criterion to grade internal validity at Concordia University Wisconsin using the American Academy of Cerebral Palsy and Developmental Medicine Method Score each of the following biases (internal validity threats) as ‘yes’ or ‘no’. Add up the total number of ‘yes’ responses out of 12. Use the following guide: 1–4=weak internal validity (score of 3); 5–8=moderate internal validity (score of 2); and 9–12=strong internal validity (score of 1). Bias relates to:

Internal validity rating form

Participants

1. Sample selection: did investigators clearly specify inclusion/exclusion criteria to minimise sample heterogeneity? In studies with a control group, this bias should affect both groups equally.

Participants

2. Attrition (participant drop out): is participant drop out less than 20% of the total sample and balanced between groups? If drop out is greater than 20% and unbalanced between groups, attrition may be a concern. Consider reasons for attrition if reported by researchers.

Participants

3. Attentional bias (Hawthorne effect): was participant behaviour unaltered by experimenter expectations or attention? This bias should affect both groups equally assuming the control or placebo group gets equal attention.

Participants

4. Baseline equality: were groups equal on important participant characteristics (e.g. age, gender, severity of disability) and outcome measures (dependent variables) at study outset? If not, were differences dealt with appropriately in data analysis?

Participants

5. Maturation or spontaneous recovery: is there no evidence that patients got better because of maturing (children) or natural healing (adults in acute phase of recovery) before and after testing? This is not a significant concern in studies where data collection is completed in a short time (single session) or if there is a control group.

Outcome measures

6. Psychometrics of dependent variables: were the outcome measures valid and reliable for measuring the outcomes of interest? In studies with a control group, this bias should affect both groups equally.

Outcome measures

7. Instrumentation bias: were the investigators careful to record information accurately and with calibrated instruments? In studies with a control group, this bias should affect both groups equally.

Outcome measures

8. Blinding: evaluator bias: was the outcome assessor unaware of group assignment (treatment or control)? Investigator bias: if possible, was the person providing the intervention blinded to group assignment?

Outcome measures

9. Testing effects: the outcomes of interest were measured such that learning or fatigue were not likely to account for changes? Did investigators take care to measure at the same time of day when testing before and after the intervention? For studies where all participants experience multiple conditions, was the order of the conditions randomised or counterbalanced? If order effects are not relevant based on the research design, a ‘yes’ is acceptable. In studies with a control group, this bias should affect both groups equally.

Research methods

10. Data analysis: was the correct statistical analysis used for the data?

Research methods

11. Adherence to the intervention: did investigators keep track of and report compliance to treatment? In studies with a control group, this bias should affect both groups equally.

Research methods

12. Co-intervention: check that participants did not begin or stop an activity/treatment in addition to their assigned intervention, and that participants assigned to control group did not begin treatment of interest (contamination). In studies with a control group, this bias should affect both groups equally.

Total Source: Mollinger and Cope (2009)

METHODS A systematic review of the literature was performed during September 2011 to evaluate the effectiveness of proprioception interventions in improving cervical position sense (PS) in patients with cervical pathology. A search for literature was performed using databases of CINAHL, the Cochrane Database of Systematic Reviews, FirstSearch, MEDLINE, PubMed and the Rehabilitation Reference Center, using combinations of the following search terms: active physical rehabilitation, cervical spine, coordination training, neck or acute whiplash, neck or cervical kinesthesia/proprioception, proprioceptive training, retraining or

proprioceptive rehabilitation training, position sense and reposition sense. The review focused on studies that measured cervical spine PS using treatment interventions individually or in combination to improve PS. All identified articles measuring cervical spine reposition sense were included in the review. Eleven studies published between 1994 and 2008 were found for various cervical treatment interventions in adult subjects with acute or long-term cervical pathology. Pain was quantified using various outcome measures in six of the identified articles. Two of the authors (Cheryl M Petersen and Rong Tang) independently extracted the following data from the selected articles: study design (all design types were included in this review); sample size;


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Critical review

Table 2. Evaluation of the 11 studies using the AACPDM method American Academy of Cerebral Palsy and Developmental Medicine evaluation of the articles based on the type of position sense detection system used to evaluate proprioception Position sense detection system

Favours treatment group (statistically and clinically significant)

Trend favouring treatment group (statistically significant only)

Head repositioning laser pointer (cm)

IB321

IIB317 IIIB219 (acupuncture and manipulation) IA335 IIIB238

IB233 IIIA244

VB129

3D Zebris CMS 70P System (degrees) 3Space Fastrak (degrees)

Favours control group

IIIA223

FASTRAK (degrees)

No treatment effect

IA24 IIIA223 IIIB239

Evidence was considered strong (indicated in red), moderate (green), or weak (blue) by considering the level of evidence, sample size and the internal validity found in each article The 3D Zebris CMS 70P System uses ultrasound signals; the 3Space Fastrak and FASTRAK are non-invasive electromagnetic devices Level of evidence: I=randomised controlled trial; II=non-randomised controlled trial with at least two groups and a control; III=non-randomised controlled trial with one group; V=single case study Numbers of subjects: A≥20; B0.50 is high (Hatala et al, 2005). Level of evidence was classified using the AACPDM method. This evidence-based evaluation methodology is used at the university where one author (Cheryl M Petersen) is a faculty member tasked with instructing the students on how to determine the level of evidence in intervention articles. The methodology has been shown to possess acceptable inter-rater reliability (κ=0.77; ρ