Research Review By Dr. Josh Plener©

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Date Posted:

May 2021

Study Title:

No Differences Between Individuals with Chronic Idiopathic Neck Pain and Asymptomatic Individuals on 7 Cervical Sensorimotor Control Tests: A Cross-sectional Study

Authors:

De Zoete R, Osmotherly P, Rivett D et al.

Author's Affiliations:

School of Health Science, Faculty of Health and Medicine, The University of Newcastle, Australia; Centre for Brain and Mental Health Research, The University of Newcastle; Hunter Medical Research Institute, New Lambton Heights, Australia; RECOVER Injury Research Centre, University of Queensland, Australia

Publication Information:

Journal of Orthopaedic & Sports Physical Therapy 2020; 50: 33-43.

Background Information:

Cervical sensorimotor control generally refers to the control and accuracy of head movements, which has been suggested to be important for the assessment of individuals with neck pain (1-4). Sensorimotor control is defined as all afferent and efferent information streams contributing to joint stability (5), consisting of multiple systems including proprioception and kinesthesis, the vestibular system, and the visuomotor system. The proprioception and kinesthetic systems are responsible for the sensation of head orientation, the vestibular system is responsible for postural balance and spatial orientation and the visuomotor system processes visual information used for all head and neck movements. It is hypothesized that if sensorimotor impairments differ between those with neck pain compared to healthy individuals, treatment interventions can be tailored to the neck pain patients (2, 6).

Past research has suggested that cervical sensorimotor control differs between neck pain individuals compared to asymptomatic individuals. However, several of these studies have significant flaws such as small sample sizes, large number of statistical tests and a lack of blinding which may lead to significant differences based on chance alone (7). In addition, there is little consistency between the study findings, as some report differences and others report no differences. Furthermore, studies that have included larger samples have an issue of heterogeneity among participants. This is a problem, as pain mechanisms and vestibular function differ between neck pain conditions (8).

Idiopathic neck pain is defined as neck pain without a clear reason for its onset, which generally develops gradually over time. It has been suggested that idiopathic neck pain individuals may present with a sensorimotor control deficit (9, 10). A recent meta-analysis identified the Joint Position Error (JPE) test as having the most support in the literature with small and statistically significant differences between participant groups, but the clinical relevance is questionable (1, 7).

Currently, cervical sensorimotor control tests are being used clinically but the evidence regarding their applicability to idiopathic neck pain patients is lacking. This study aimed to report outcomes on 7 cervical sensorimotor control tests and investigate whether there are differences in these outcomes in individuals with chronic idiopathic neck pain compared to asymptomatic individuals. The 7 cervical sensorimotor tests that were used were: joint position error, postural balance, subjective visual vertical, head-tilt response, “the Fly” test, head steadiness, and smooth pursuit neck torsion.

Pertinent Results:

50 chronic neck pain and 50 asymptomatic control participants were recruited. The baseline parameters were not significantly different between the groups.

The assessed range of motion was significantly less for idiopathic neck pain participants compared to asymptomatic controls.

Interestingly, there were no significant differences between individuals with idiopathic neck pain and asymptomatic individuals for any of the sensorimotor tests.

Only weak correlations existed between cervical sensorimotor control tests and the level of neck pain and disability. Only two of the correlations were significant: 1) the head tilt response and current neck pain intensity (p = 0.042); and 2) the head tilt response and neck disability (p = 0.029).

All cervical sensorimotor tests except for the joint position error (JPE) test were skewed to the right, indicating that there were only a few poor performers. Furthermore, for each test the proportion of poor performers in the neck pain group compared to asymptomatic individuals were not significantly different.

Clinical Application & Conclusions:

The results of this study demonstrated that no differences exist between individuals with chronic idiopathic neck pain and age and sex-matched asymptomatic control participants with regards to cervical sensorimotor control test outcomes. Each test was only weakly correlated with pain and disability. All tests except for the joint position error test were positively skewed, meaning that most participants performed well on the test. Therefore, their clinical utility in discriminating between individuals with and without neck pain is questionable. It is possible that these tests are not valid tools to assess sensorimotor control in idiopathic neck pain patients as currently there is no gold standard to compare.

The current evidence for the use of sensorimotor control tests in idiopathic neck pain patients is inconsistent and lacks efficacy (1). One possibility for nonsignificant findings is that the tests are not sensitive enough to discriminate between individuals with chronic idiopathic neck pain compared to asymptomatic individuals. Another possibility is that the tests have an inherent ceiling effect and may not be capable of discriminating very good performance from good performance. Further research may be required in order to determine a new test that can measure clinically relevant changes in people with neck pain compared to asymptomatic individuals. A third possibility is that there is no difference between the two groups and the distribution seen in the study represents a normal spread of biological responses. The fact that there were only weak correlations between cervical sensorimotor outcomes and levels of neck pain and neck disability strengthen the fact that these tests do not discriminate between groups.

EDITOR’S NOTE: I found the results of this study a bit surprising, as these tests have become popular for assessing patients with not only neck pain, but dizziness and vertigo, concussion and whiplash associated disorders. I have included them in the curriculum in seminars and lectures and I use many of these tests in my own practice. My take on the results of this study, for what it’s worth, is that these tests may be more useful for concussion or whiplash patients, or those presenting with dizziness or vertigo. Ultimately, these tests can give you some information about an individual patient – specifically, their deficits with some of these tasks, each of which could provide a treatment target or potential method of rehab to utilize in their care plan. They can also indicate that an individual may have no relevant deficit in this domain (SMI). These tests, as suggested by the results of this study, may NOT be able to differentiate neck pain patients from those without neck pain. I say, so what? Remember – most of the time patients who see us already have neck pain, so we don’t need these tests for that purpose anyway.

Study Methods:

This was a cross-sectional study conducted between July 2016 to June 2017.

Sample Size: The minimum sample size was calculated in order to detect a difference between groups at an alpha level of 0.05 and power of 80%. The largest sample-size estimate used a 0.75 degree variability in score on the subjective visual vertical test to indicate that a 0.5 degree difference between groups would be detected with 36 participants per group. Therefore, 50 participants per group were recruited to allow for withdrawals.

Participants: Recruitment occurred via flyers, the local research participant volunteer registry, local newspaper advertising, social media advertising and patients attending local physical therapy practices.

Inclusion criteria:
  • Participants with chronic idiopathic neck pain had neck pain that was spontaneous with an unknown cause
  • 18 years of age or older
  • Neck pain of at least 4/10 intensity on a numeric rating scale at the time they inquired about the study
  • Neck pain lasting for 12 weeks or longer
Asymptomatic participants had no current neck pain and had never sought treatment for neck pain. These participants were matched for sex and age with neck pain individuals.

Exclusion criteria: Neck pain and asymptomatic participants were excluded if they had limited vision after correction, diabetes, migraine headaches, history of neck trauma or surgery. Furthermore, individuals with neurological or musculoskeletal conditions that were considered to affect sensorimotor control such as: low back pain, scoliosis, neuralgia, complex regional pain syndrome, joint reconstructions, or anterior cruciate ligament repairs were excluded.

Cervical Sensorimotor Control Tests
 
Joint Position Error:
  1. Conventional: A laser pointer was placed on the participant’s head and was pointed towards a wall. The participant was instructed to move away from the centre of the target, and then asked to return to the starting position. Participants were blindfolded and a foam cushion was placed under their feet to limit sensory reference information.
  2. Torsion: A laser pointer was attached to the participant’s mid-sternum region, lined up to the centre of the target. The examiner held the participant’s head to maintain neutral while the participant rotated their trunk away from the target and then asked to rotate back to the starting position.
Postural Balance
  1. Conventional: The participant was asked to stand in a comfortable stance for 30 seconds under 6 conditions.
  2. Torsion: The examiner held the participant’s head in neutral while the participant rotated the trunk and lower limbs 45 degrees.
Subjective Visual Vertical:
Using a virtual reality device, 2 dots representing the end points of a 20-degree tilted imaginary line were presented within a square that was tilted 18 degrees. The participant was instructed to reposition the dots to the imaginary line, which was positioned vertically, using the computer mouse to rotate the dots.

Head Tilt Response:
In a virtual reality device, a white line tilted either 5 or 15 degrees clockwise or 25 or 15 degrees counter-clockwise was displayed. The participant laterally flexed their neck so the line was positioned exactly vertical. While holding the head still in this position, the head position was recorded before the next line was presented.

The Fly:
A representation of the head position was displayed with a plus sign as a moving target on a computer screen. The participant was instructed to move their head in order to follow the target and place the “+” over the target.

Head Steadiness:
The participant was asked to lift their head approximately 1 cm off the table and hold it stationary for 40 seconds. A low load condition was investigated, where the participant was seated on a treatment table with their back and head supported at an angle of 60 degrees, and a high load condition where the participant laid supine on a horizontal treatment table.

Smooth Pursuit Neck Torsion:
A motor was positioned behind the participant with a laser pointer attached. The laser pointer was projected onto the wall which smoothly oscillated left and right with a constant speed, visual angle and frequency. The participant needed to follow the moving target with their eyes while keeping their head still in a neutral position. This was done in various positions including: the body facing straight ahead, the body rotated 45 degrees in a right torsion position and the body rotated 45 degrees in a left torsion position while their head was kept still.

Further Procedures:
 
Physical activity levels were quantified using the Godin-Shephard Leisure-Time Physical Activity Questionnaire (11). Neck pain participants completed three VAS scales to assess their current pain, their average pain over the last 7 days and their average pain over the last 4 weeks. This was done as VAS responses vary with different recall periods in neck pain patients (12). The Neck Disability Index (NDI) was used to assess perceived disability (13). In addition, cervical range of motion in rotation, flexion and extension was quantified with the Cervical Range of Motion instrument (14). This was done 3 times and the average of the 3 trials were used to calculate the total range of motion in each plane. Range of motion was used as this is a physical measure which is commonly impaired in chronic idiopathic neck pain individuals. The order of range of motion tests and cervical sensorimotor tests were randomized.

Data Analysis:
 
Mann-Whitney U tests determined differences in range of motion and cervical sensorimotor test outcomes between groups.

For neck pain participants, the Spearman rho was used to determine correlations between cervical sensorimotor test outcomes and levels of pain and disability.

The number of tests where a participant performed poorly was summed to determine whether poor performance on multiple tests related to pain, disability, or other participant characteristics.

Differences in the proportion of poor performers within the neck pain and asymptomatic groups were determined using chi-square tests.

Study Strengths / Weaknesses:

Strengths:
  • This study consisted of a large, relatively homogenous sample while incorporating multiple cervical sensorimotor control test outcomes.
  • Groups were well matched for sex, age, body mass index, and physical activity level which are all thought to influence cervical sensorimotor control.
  • The median ages of both groups were similar to populations studied in previous studies.
  • Collaboration with research groups that developed each test took place in order to perform the tests in a similar manner that they were intended and originally studied.
  • Bias during data collection was minimized, as most tests utilized computerized data collection and therefore assessors had minimal influence on the recording or calculation of outcomes.
Weaknesses:
  • All tests were performed in 1 session so the participants’ ability to perform the tests may have improved throughout the session. However, to prevent a practice effect the order of the tests were randomized.
  • The neck pain group had high levels of physical activity which was similar to the asymptomatic control group. Higher physical activity levels may contribute to improved performance on the cervical sensorimotor control tests.

Additional References:

  1. de Zoete RMJ, Osmotherly PG, Rivett DA, et al. Sensorimotor control in indi¬viduals with idiopathic neck pain and healthy in¬dividuals: a systematic review and meta-analysis. Arch Phys Med Rehabil 2017; 98: 1257-1271.
  2. Elsig S, Luomajoki H, Sattelmayer M, et al. Sensorimotor tests, such as movement control and laterality judgment accuracy, in persons with recurrent neck pain and controls. A case-control study. Man Ther 2014; 19: 555-561.
  3. Kristjansson E, Dall’Alba P, Jull G. A study of five cervicocephalic relocation tests in three different subject groups. Clin Rehabil 2003; 17: 768-774.
  4. Sjölander P, Michaelson P, Jaric S, et al. Sensorimotor disturbances in chronic neck pain—range of motion, peak velocity, smooth¬ness of movement, and repositioning acuity. Man Ther 2008; 13: 122-131.
  5. Riemann BL, Lephart SM. The sensorimotor system, part I: the physiologic basis of functional joint stability. J Athl Train 2002; 37: 71-79.
  6. Armstrong B, McNair P, Taylor D. Head and neck position sense. Sports Med 2008; 38: 101-117.
  7. Stanton TR, Leake HB, Chalmers KJ, et al. Evidence of impaired proprioception in chronic, idiopathic neck pain: systematic review and meta-analysis. Phys Ther 2016; 96: 876-887.
  8. Scott D, Jull G, Sterling M. Widespread sensory hypersensitivity is a feature of chronic whiplash-associated disorder but not chronic idiopathic neck pain. Clin J Pain 2005; 21: 175-181.
  9. Jørgensen MB, Skotte JH, Holtermann A, et al. Neck pain and postural balance among workers with high postural demands - a cross-sectional study. BMC Musculoskelet Disord 2011; 12: 176.
  10. Kristjansson E, Dall’Alba P, Jull G. A study of five cervicocephalic relocation tests in three different subject groups. Clin Rehabil 2003; 17: 768-774.
  11. Godin G, Shephard RJ. A simple method to as¬sess exercise behavior in the community. Can J Appl Sport Sci 1985; 10: 141-146.
  12. Kamper SJ, Grootjans SJ, Michaleff ZA, Maher CG, McAuley JH, Sterling M. Measuring pain intensity in patients with neck pain: does it mat¬ter how you do it? Pain Pract 2015; 15: 159-167.
  13. Vernon H, Mior S. The Neck Disability Index: a study of reliability and validity. J Manipulative Physiol Ther 1991; 14: 409-415.
  14. Audette I, Dumas JP, Côté JN, De Serres SJ. Validity and between-day reliability of the cervi¬cal range of motion (CROM) device. J Orthop Sports Phys Ther 2010; 40: 318-323.