Head Eye Co-ordination Using Simultaneous Measurement of Eye in Head and Head in Space Movements: Potential For Use in Subjects With a Whiplash Injury

Objective. Describe reproducibility of a measurement method to investigate deficits in eye-head co-ordination. Methods. Combined recordings of head and eye rotation using wireless motion sensors and electro-oculography (EOG) were used as an initial step towards a method to quantify eye-head co-ordination deficits. Head rotation to the side during gaze fixation and sequential head and eye movements were studied on 20 asymptomatic control subjects and six subjects with chronic whiplash disorders. All included whiplash subjects reported eye disturbances according to a vision symptom questionnaire. Results. The trial-to-trial reproducibility was moderate to high for 24 of 28 variables (Intraclass Correlation Coefficient 0.44 to 0.87). Velocity gain (ratio of eye and head velocities) was on average close to unity in both groups. Head stability was high in control subjects, while three of six whiplash subjects demonstrated head instability during eye movement. Whiplash subjects also demonstrated a decreased range of head movement during gaze fixation and lower head velocities as compared with the asymptomatics. Conclusions. The method of combined head and eye motion appears to give accurate, repeatable measurements. Case studies of whiplash subjects indicated deficits in head eye co-ordination. The method could be useful in further clinical research into eye and head movement in those with neck disorders. Grip H, Jull G, Treleaven J. Head eye co-ordination using simultaneous measurement of eye in head and head in space movements: potential for use in subjects with a whiplash injury.     

Discrimination between pain-induced head movement disturbances after whiplash injuries and their simulation

Neck pain after whiplash injury of the cervical spine often induces typical changes in head motion patterns (amplitude, velocity). These changes of kinematics may help to recognize malingerers. We investigated the hypothesis that malingerers are not able to reproduce their simulated head movement disturbances three times. The kinematics of head movements of 23 patients with neck pain after whiplash injury and of 22 healthy subjects trying to act as malingerers were compared. The healthy subjects were informed about the symptomatology of whiplash injury and were asked to simulate painful head movements. Two different kinds of head movements were registered and analyzed by Cervicomotography: (1) the slow free axial head rotation (yaw) and (2) the axial head rotation (yaw) tracking a moving visual target. Each experimental condition was presented three times, expecting the malingerers not to be able to produce as well as to reproduce the same head movement disturbances again and again. In patients, as a consequence of their distinct pain patterns, we expected less variance between the test repetitions. The statistical analysis showed significant differences of the calculated kinematic parameters between both groups and the inability of healthy subjects to simulate and to reproduce convincingly distinct pain patterns.     

Individuelle Stereotype der Koordination von Kopf- und Augenbewegungen

Background

Combined head and eye movements together with trunk movements define the visual field. Changes in surrounding conditions for the combination of eye and head movements in gaze shift movements cause changes in the use of neck and shoulder muscles. The individual relationship between head and eye movement may influence the development of painful symptoms in neck and shoulder muscles if the individual relationship cannot be realized.

Method

Children of various age groups and a group of patients with neck and shoulder pain were tested by alternately looking at a centrally and two peripherally placed shining diodes. This resulted in a gaze shift of 40° to the left or right. An ultrasound system was used to detect the horizontal head movement relative to the midline.

Results

In the group of patients with neck and shoulder pain 82% of subjects showed a proportion of eye movement in gaze shift of greater than 50%. In the age group of 6- and 7-year-old children, the proportion of head movement was greater than 50%.

Conclusion

In children a type of gaze motoric is dominant which predominantly consists of head movement. Physiological foundations for a connection between the stereotypes of gaze motoric and the origin of neck and shoulder pain are discussed.     

The effect of neck torsion on postural stability in subjects with persistent whiplash

Dysfunction of cervical receptors in neck disorders has been shown to lead to disturbances in postural stability. The neck torsion manoeuvre used in the smooth pursuit neck torsion (SPNT) test is thought to be a specific measure of neck afferent dysfunction on eye movement in those with neck pain. This study aimed to determine whether neck torsion could change balance responses in those with persistent whiplash-associated disorders (WADs). Twenty subjects with persistent WAD and 20 healthy controls aged between 18 and 50 years stood on a computerised force plate with eyes closed in comfortable stance under 5 conditions: neutral head, head turned to left and right and neck torsion to left and right. Root mean square (rms) amplitude of sway was measured in the anterior-posterior (AP) and medial-lateral (ML) directions. The whiplash group had significantly greater rms amplitude in the AP direction following neck torsion compared to the control group (p < 0.03). The results show that the neck torsion manoeuvre may lead to greater postural deficits in individuals with persistent WAD and provides further evidence of neck torsion to identify abnormal cervical afferent input, as an underlying cause of balance disturbances in WAD. Further research is warranted.     

Sensorimotor disturbances in chronic neck pain--range of motion, peak velocity, smoothness of movement, and repositioning acuity

The purpose of this pilot study was to evaluate sensorimotor functions in patients with chronic neck pain with objective and quantitative methods. A group of 16 patients with chronic idiopathic neck pain of insidious onset or whiplash associated disorders (WAD) was compared to an equally sized group of healthy subjects. Kinematics were investigated during voluntary head rotations by measuring range of motion, variability of range of motion (ROM-Variability), peak velocity, and smoothness of movement (jerk index). Repositioning acuity after cervical rotations was evaluated by analysing constant and variable error (VE). In comparison to the healthy subjects, the patients showed significantly larger jerk index, ROM-Variability and VE. No statistically significant differences were found between insidious neck pain and WAD. It is concluded that jerky and irregular cervical movements and poor position sense acuity are characteristic sensorimotor symptoms in chronic neck pain. The observed individuality in sensorimotor disturbances emphasizes the importance of developing specific rehabilitation programs for specific dysfunctions, and of using objective and quantitative methods for evaluation of rehabilitation.     

Smooth pursuit neck torsion test in whiplash-associated disorders: relationship to self-reports of neck pain and disability, dizziness and anxiety.

OBJECTIVE: The smooth pursuit neck torsion test is thought to be a measure of neck afferent influence on eye movement control and is useful in assessing subjects with whiplash, especially those complaining of dizziness. Nevertheless, it is not known whether impairments identified relate only to abnormal cervical afferentation or are influenced by levels of anxiety or neck pain. DESIGN: A prospective, 3-group, observational design. SUBJECTS: One hundred subjects with persistent whiplash (50 complaining of dizziness, 50 not complaining of dizziness) and 50 healthy controls. METHODS: The smooth pursuit neck torsion test was performed and analysed taking into account subjects' reported levels of pain, anxiety and dizziness. RESULTS: The results confirm that there are significant (p<0.01) differences in the smooth pursuit neck torsion test between subjects with persistent whiplash both with dizziness (mean 0.11) and without dizziness (mean 0.07) compared with healthy control subjects (mean 0.01). The results suggest that the test is not influenced by a patients' level of anxiety, but may be influenced by both nocioceptive and proprioceptive factors. CONCLUSION: The results provide further evidence of the usefulness of the smooth pursuit neck torsion test to identify eye movement disturbances in patients with whiplash, which are likely to be due to disturbed cervical afferentation.     

Variations in the axis of motion during head repositioning--a comparison of subjects with whiplash-associated disorders or non-specific neck pain and healthy controls

BACKGROUND: The ability to reproduce head position can be affected in patients after a neck injury. The repositioning error is commonly used as a measure of proprioception, but variations in the movement might provide additional information. METHODS: The axis of motion and target performance were analyzed during a head repositioning task (flexion, extension and side rotations) for 24 control subjects, 22 subjects with whiplash-associated disorders and 21 with non-specific neck pain. Questionnaires regarding pain intensity and fear avoidance were collected. Head position and axis of motion parameters were calculated using a helical axis model with a moving window of 4 degrees . FINDINGS: During flexion the whiplash group had a larger constant repositioning error than the control group (-1.8(2.9) degrees vs. 0.1(2.4) degrees , P=0.04). The axis was more inferior in both neck pain groups (12.0(1.6)cm vs. 14.5(2.0)cm, P<0.05) indicating movement at a lower level in the spine. Including pain intensity from shoulder and neck region as covariates showed an effect on the axis position (P=0.03 and 0.04). During axial rotation to the left there was more variation in axis direction for neckpain groups as compared with controls (4.0(1.7) degrees and 3.7(2.4) degrees vs. 2.3(1.9) degrees , P=0.01 and 0.05). No significant difference in fear avoidance was found between the two neck pain groups. INTERPRETATION: Measuring variation in the axis of motion together with target performance gives objective measures on proprioceptive ability that are difficult to quantify by visual inspection. Repositioning errors were in general small, suggesting it is not sufficient as a single measurement variable in a clinical situation, but should be measured in combination with other tests, such as range of motion.     

Are altered smooth pursuit eye movements related to chronic pain and disability following whiplash injuries? A prospective trial with one-year follow-up

OBJECTIVE: To evaluate the ability of early smooth pursuit testing to predict chronic whiplash-associated disorders, and to study whether the presence of abnormal smooth pursuit eye movements at one-year follow-up is associated with symptoms at that time. DESIGN: Prospective cohort study with one-year follow-up. SETTING: The study was carried out at a university research centre and participants were recruited from emergency units and general practitioners. SUBJECTS: In all, 262 participants were recruited within 10 days from a whiplash injury. MAIN MEASURES: Smooth pursuit eye movements were tested with electrooculography (EOG) an average of 12 days after a whiplash trauma and again after one year. Analyses of EOG recordings were computerized. Associations between test results both from baseline and one-year tests and self-reported neck pain, headache, neck disability and working ability one year after the car collision were determined. RESULTS: Results of early eye movement tests were not associated with the prognosis. Reduced smooth pursuit performance when tested in static cervical rotation at the one-year follow-up was significantly associated with higher neck pain intensity at that time (regression coefficient 0.8, 95% confidence interval (CI) 0.04-1.5), but the association was too weak for the test to discriminate between recovered participants and those with lasting symptoms. CONCLUSIONS: Although reduced smooth pursuit performance at one-year follow-up was associated with persistent neck pain, smooth pursuit eye movement tests are not useful as predictive or diagnostic tests in whiplash-associated disorders.     

Effects of dry needling of the obliquus capitis inferior on sensorimotor control and cervical mobility in people with neck pain: A double-blind,randomized sham-controlled trial

BackgroundImpairments of sensorimotor control relating to head and eye movement control and postural stability are often present in people with neck pain. The upper cervical spine and particularly the obliquus capitis inferior (OCI) play an important proprioceptive role; and its impairment may alter cervical sensorimotor control. Dry needling (DN) is a valid technique to target the OCI.ObjectivesTo investigate if a single DN session of the OCI muscle improves head and eye movement control-related outcomes, postural stability, and cervical mobility in people with neck pain.MethodsForty people with neck pain were randomly assigned to receive a single session of DN or sham needling of the OCI. Cervical joint position error (JPE), cervical movement sense, standing balance and oculomotor control were examined at baseline, immediately post-intervention, and at one-week follow-up. Active cervical rotation range of motion and the flexion rotation test were used to examine the global and upper cervical rotation mobility, respectively.ResultsLinear mixed-models revealed that the DN group showed a decrease of JPE immediately post-intervention compared to the sham group (mean difference [MD]= -0.93°; 95% confidence interval [CI]: -1.85, -0.02) which was maintained at one-week follow-up (MD= -1.64°; 95%CI: -2.85, -0.43). No effects on standing balance or cervical movement sense were observed in both groups. Upper cervical mobility showed an increase immediately after DN compared to the sham group (MD= 5.14°; 95%CI: 0.77, 9.75) which remained stable at one-week follow-up (MD= 6.98°; 95%CI: 1.31, 12.40). Both group showed an immediate increase in global cervical mobility (MD= -0.14°; 95%CI: -5.29, 4.89).ConclusionThe results from the current study suggest that a single session of DN of the OCI reduces JPE deficits and increases upper cervical mobility in patients with neck pain. Future trials should examine if the addition of this technique to sensorimotor control training add further benefits in the management of neck pain.     

A Pilot Longitudinal Study of 3-Dimensional Head and Neck Kinematics During Functional Tasks in Individuals With Chronic Idiopathic Neck Pain Either Wait-Listed for or Receiving Chiropractic Spinal Manipulative Therapy With Exercise

ObjectiveThe purpose of this study was to determine if there is a relationship between pain and movement kinematics during functional tasks, evaluated over time, in individuals with chronic idiopathic neck pain.MethodsTen participants with chronic idiopathic neck pain performed 2 functional tasks (overhead reach to the right and putting on a seatbelt) while evaluated using 8 Oqus 300+ cameras. Kinematic variables included joint angles and range of motion (ROM) (°), head segment relative to neck segment (head-neck [HN]); and head/neck segment relative to upper thoracic segment (head/neck-trunk), velocity (m/s), and time (% of movement phase). Pain was quantified using a 100-mm visual analog scale. Linear mixed effects regression models were used to analyze associations between pain and kinematic variables adjusting for treatment group.ResultsFor overhead reach, higher pain was associated with less HN peak rotation at baseline (β = –0.33; 95% CI −0.52 to –0.14, P = .003) and less HN total rotation ROM at 6 months (β = –0.19; 95% CI –0.38 to –0.003, P = .048). For the seatbelt task, higher pain was associated with less HN peak rotation (β = –0.52; 95% CI −0.74 to –0.30 to –0.74, P < .001) and less HN total rotation ROM at baseline (β = –0.32; 95% CI –0.53 to –0.10, P = .006). No other movement variables demonstrated meaningful relationships with pain for the reach or seatbelt tasks.ConclusionHigher pain is associated with less HN peak and total rotation during functional reaching tasks requiring head rotation. Recognizing altered functional kinematics in individuals with chronic neck pain may assist patient management.     

Development of motor system dysfunction following whiplash injury

Dysfunction in the motor system is a feature of persistent whiplash associated disorders. Little is known about motor dysfunction in the early stages following injury and of its progress in those persons who recover and those who develop persistent symptoms. This study measured prospectively, motor system function (cervical range of movement (ROM), joint position error (JPE) and activity of the superficial neck flexors (EMG) during a test of cranio-cervical flexion) as well as a measure of fear of re-injury (TAMPA) in 66 whiplash subjects within 1 month of injury and then 2 and 3 months post injury. Subjects were classified at 3 months post injury using scores on the neck disability index: recovered (<8), mild pain and disability (10-28) or moderate/severe pain and disability (>30). Motor system function was also measured in 20 control subjects. All whiplash groups demonstrated decreased ROM and increased EMG (compared to controls) at 1 month post injury. This deficit persisted in the group with moderate/severe symptoms but returned to within normal limits in those who had recovered or reported persistent mild pain at 3 months. Increased EMG persisted for 3 months in all whiplash groups. Only the moderate/severe group showed greater JPE, within 1 month of injury, which remained unchanged at 3 months. TAMPA scores of the moderate/severe group were higher than those of the other two groups. The differences in TAMPA did not impact on ROM, EMG or JPE. This study identifies, for the first time, deficits in the motor system, as early as 1 month post whiplash injury, that persisted not only in those reporting moderate/severe symptoms at 3 months but also in subjects who recovered and those with persistent mild symptoms.     

Dynamic and functional balance tasks in subjects with persistent whiplash: a pilot trial

Disturbances in static balance have been demonstrated in subjects with persistent whiplash. Some also report loss of balance and falls. These disturbances may contribute to difficulties in dynamic tasks. The aim of this study was to determine whether subjects with whiplash had deficits in dynamic and functional balance tasks when compared to a healthy control group. Twenty subjects with persistent pain following a whiplash injury and twenty healthy controls were assessed in single leg stance with eyes open and closed, the step test, Fukuda stepping test, tandem walk on a firm and soft surface, Singleton test with eyes open and closed, a stair walking test and the timed 10 m walk with and without head movement. Subjects with whiplash demonstrated significant deficits (p < 0.01) in single leg stance with eyes closed, the step test, tandem walk on a firm and soft surface, stair walking and the timed 10 m walk with and without head movement when compared to the control subjects. Specific assessment and rehabilitation directed towards improving these deficits may need to be considered in the management of patients with persistent whiplash if these results are confirmed in a larger cohort.     

Cervicocephalic kinesthetic sensibility in patients with chronic, nontraumatic cervical spine pain.

OBJECTIVE: To investigate cervicocephalic kinesthetic sensibility (head repositioning accuracy to subjective straight ahead) in patients with chronic, nontraumatic cervical spine pain. DESIGN: A prospective, 2-group, observational design. SETTING: An outpatient chiropractic clinic in the United Kingdom. PARTICIPANTS: Eleven patients (6 men, 5 women; mean age +/- standard deviation, 41.1 +/- 13.3 yr; range, 18-55 yr) with chronic, nontraumatic cervical spine pain (mean duration, 24 +/- 18 mo), with no evidence of cervical radiculopathy and/or myelopathy or any other neurologic disorder. Eleven asymptomatic, unimpaired volunteers (5 men, 6 women; mean age, 39.3 +/- 10.3 yr; range, 28-54 yr) with no history of whiplash or other cervical spine injury or pain served as controls. MAIN OUTCOME MEASURES: Cervicocephalic kinesthetic sensibility was investigated by testing the ability of blindfolded participants to relocate accurately the head on the trunk, to a subjective straight-ahead position, after a near-maximal active movement of the head in the horizontal or vertical plane. The active cervical range of motion and the duration and intensity of neck pain were also recorded. RESULTS: Mann-Whitney U testing indicated that the patient (P) group was no less accurate in head repositioning than the control (C) group for all movement directions except flexion (median global positioning error [95% confidence interval], P = 5.7 degrees [5.03-9.10], C = 4.2 degrees [3.17-5.32]; p <.05). CONCLUSIONS: Nontraumatic neck pain patients show little evidence of impaired cervicocephalic kinesthetic sensibility. These results contrast with studies of chronic cervical pain patients in which the origin was not controlled or involved a cervical whiplash injury.     

Quantitative posturography in altered sensory conditions: a way to assess balance instability in patients with chronic whiplash injury

OBJECTIVES: To quantify neck mobility and posture with and without various postural perturbations. DESIGN: A multivariable 2-group study with repeated measures and treatments. SETTING: A human performance laboratory. PARTICIPANTS: Eleven patients with chronic whiplash injury (mean age, 33.3+/-6.7 y; weight, 73.4+/-11.4 kg; height, 173.3+/-7.2 cm) with a sex- and age-matched control group (mean age, 33.1+/-6.8 y; weight, 68+/-12.5 kg; height, 171.5+/-6.3 cm). INTERVENTIONS: Neck mobility and the effects of postural perturbations affecting the visual, vestibular, cutaneous, proprioceptive, and nociceptive systems were measured. MAIN OUTCOME MEASURES: Active range of motion, neck position sense, and postural activity. RESULTS: We found significantly reduced neck mobility and increased postural activity in the patient group compared with the control group. In patients, there was significantly greater postural activity with eyes closed, eyes open and speaking, and eyes closed with Achilles' tendons vibrations compared with eyes open with no vibrations. In the controls, there was no significant effect of experimental muscle pain on postural activity. CONCLUSIONS: Patients with chronic whiplash injury had a protective response to neck movement and different tuning, sequencing, and execution of the postural synergies probably because of excessive reliance on visual input despite a possible deficit and altered vestibular and/or proprioceptive activity. In healthy volunteers, the pain induced by a single bolus injection of hypertonic saline was probably too limited in intensity and spreading to decrease postural stability.     

Variability of neck and trunk movement during single- and dual-task gait in people with chronic neck pain

BackgroundPrevious findings reported that people with chronic neck pain walk with reduced range trunk rotation, especially when walking in more challenging conditions. Quantification of the quality of neck and trunk movement during gait could provide further insight into biomechanical changes that occur in people with neck pain. This study uniquely compared the variability of trunk and neck rotation during single-task and dual-task gait in people with chronic neck pain and asymptomatic individuals.MethodsAn observational case-control study was conducted on 20 asymptomatic individuals and 24 people with chronic neck pain of idiopathic or traumatic origin. Participants performed rectilinear walking whilst keeping the head in a neutral position (single-task) and whilst rotating the head at a natural speed (dual-task). Trunk and head rotation angles were averaged across gait cycles for the task trials. The data were normalised in time, and the average variability of angular distribution along the normalised cycle was extracted. The Tampa Scale for Kinesiophobia was used to assess fear of movement.FindingsDuring single-task gait, there were no group differences for the variability of trunk (p = 0.862) or neck (p = 0.427) rotation. For dual-task gait, there was no difference between groups for the variability of neck rotation (p = 0.636), however, the participants with neck pain displayed reduced variability of trunk rotation (p = 0.021). The neck pain group also walked at a significantly slower speed during dual-task gait (p = 0.043) compared to asymptomatic individuals and the speed of their gait was associated with the extent of fear of movement.InterpretationThe strategy observed in participants with chronic neck pain likely reflects adaptive behaviour when faced with more challenging conditions for postural control.     

Head and neck position sense in whiplash patients and healthy individuals and the effect of the cranio-cervical flexion action

BACKGROUND: Whiplash may damage structures within the neck that can affect position sense. Deep neck flexor muscle retraining may improve position sense. The current study compared range of motion and position sense in whiplash and control subjects and investigated the effects of a muscle training session on position sense. METHODS: Twenty-three subjects with whiplash were compared with a matched control group. Range of motion and neck position sense measures were recorded using the 3-Space Fastrak. Measures of function were also assessed in the whiplash group. Subjects were then randomised into experimental and control groups and the former group received a training session to activate the deep neck flexor and scapular stabilising muscles (the cranio-cervical flexion action) during head and neck movements. After training, position sense measures were re-evaluated. FINDINGS: Results showed significant reductions (P < 0.05) in active range of motion in the whiplash group when compared to the healthy group. No significant differences (P > 0.05) between whiplash and healthy groups in position matching accuracy were observed. Functional outcome scores indicated the whiplash group to be mildly disabled. No effect on error scores was observed when position-matching tasks were performed with and without the cranio-cervical flexion action. Correlations between functional measures or range of motion, and position sense were not significant. INTERPRETATION: There was no evidence of position sense impairment in the mildly disabled whiplash subjects. The performance of the cranio-cervical flexion action had no effect on position sense, and hence clinical improvements observed from using this action may be more associated with mechanical stabilisation.     

Immediate effects of the central posteroanterior mobilization technique on pain and range of motion in patients with mechanical neck pain

Purpose.?To determine the immediate effects of the central posteroanterior (PA) mobilization technique on both pain and active cervical range of motion in patients with mechanical neck pain presenting with central or bilateral symptoms.

Methods.?A randomized controlled trial was conducted in 60 patients who were randomly allocated into either ‘central PA’ or ‘random’ mobilization group. Two physical therapists and one assessor participated. Outcome measures included neck pain at rest, pain on the most painful movement, and active cervical range of motion taken before and immediately 5?min after the mobilization treatment.

Results.?Significant reductions in pain at rest and on the most painful movement were noted within-group comparisons (p?<?0.001). However, the ‘central PA’ mobilization group obtained a significantly greater reduction in pain on the most painful movement than the ‘random’ mobilization group (p?<?0.05). Both mobilization techniques had no effects on the active cervical range of motion. However, the differences in the means of pain reduction between both mobilization techniques were modest (<10?mm).

Conclusion.?The clinical recommendation regarding the selection of the central PA mobilization technique for treating patients with central or bilateral mechanical neck pain is therefore arguably.     

Neck kinematics and sternocleidomastoid muscle activation during neck rotation in subjects with forward head posture

[Purpose] The present study investigated differences in the kinematics of the neck and activation of the sternocleidomastoid (SCM) muscle during neck rotation between subjects with and without forward head posture (FHP). [Subjects and Methods] Twenty-eight subjects participated in the study (14 with FHP, 14 without FHP). Subjects performed neck rotation in two directions, left and right. The kinematics of rotation-lateral flexion movement patterns were recorded using motion analysis. Activity in the bilateral SCM muscles was measured using surface electromyography. Differences in neck kinematics and activation of SCM between the groups were analyzed by independent t-tests. [Results] Maintaining FHP increased the rotation-lateral flexion ratio significantly in both directions. The FHP group had significantly faster onset time for lateral flexion movement in both directions during neck rotation. Regarding the electromyography of the SCM muscles during neck rotation in both directions, the activity values of subjects with FHP were greater than those of subjects without FHP for the contralateral SCM muscles. [Conclusion] FHP can induce changes in movement in the frontal plane and SCM muscle activation during neck rotation. Thus, clinicians should consider movement in the frontal plane as well as in the sagittal plane when assessing and treating patients with forward head posture.Key words: Axial rotation, Cervical movement, Forward head posture     

Changes in head and neck position have a greater effect on elbow joint position sense in people with whiplash-associated disorders

BACKGROUND: It has been shown that perception of elbow joint position is affected by changes in head and neck position. Further, people with whiplash-associated disorders (WAD) present with deficits in upper limb coordination and movement. OBJECTIVES: This study is aimed to determine whether the effect of changes in head position on elbow joint position error (JPE) is more pronounced in people with WAD, and to determine whether this is related to the participant's pain and anxiety levels. METHODS: Nine people with chronic and disabling WAD and 11 healthy people participated in this experiment. The ability to reproduce a position at the elbow joint was assessed after changes in the position of the head and neck to 30 degrees , and with the head in the midline. Pain was monitored in WAD participants. RESULTS: Absolute elbow JPE with the head in neutral was not different between WAD and control participants (P=0.5). Changes in the head and neck position increased absolute elbow JPE in the WAD group (P<0.05), but did not affect elbow JPE in the control group (P=0.4). There was a connection between pain during testing and the effect of changes in head position on elbow JPE (P<0.05). DISCUSSION: Elbow JPE is affected by movement of the head and neck, with smaller angles of neck rotation in people with WAD than in healthy individuals. This observation may explain deficits in upper limb coordination in people with WAD, which may be due to the presence of pain or reduced range of motion in this population.     

Variability of the helical axis during active cervical movements in people with chronic neck pain

BackgroundRecent work described parameters of the helical axis in asymptomatic people with potential for investigating kinematic changes in the cervical region. This approach could provide novel information on movement variability in people with neck pain, however this has never been investigated. This study aimed to investigate movement variability during active neck movements performed at different speeds in people with and without chronic neck pain.MethodsThis observational case-control study examined 18 participants with chronic neck pain of either idiopathic or traumatic origin and 18 gender-matched asymptomatic participants. Cervical kinematics were captured with 3D motion capture as people with and without chronic neck pain performed flexion-extension, bilateral lateral flexion and bilateral rotation at different speeds (natural, slow, and fast). The mean distance and mean angle parameters of the helical axis were extracted to describe 3D motion and quantify movement variability.FindingsA smaller mean distance was observed in those with neck pain compared to the asymptomatic participants during flexion-extension (P = 0.019) and rotation movements (P = 0.007). The neck pain group displayed smaller values for the mean angle during rotation movements with different speeds (P = 0.01). These findings indicate less variable movement for those with neck pain relative to the asymptomatic participants. No difference in the mean angle was observed between groups for flexion-extension and lateral flexion.InterpretationThe findings reiterate the importance of data derived from kinematic measures, and its potential for providing clinicians with further insight into the quality of active neck movements in people with chronic neck pain.