Michele Sterling

Sensory hypersensitivity occurs soon after whiplash injury and is associated with poor recovery

Hypersensitivity to a variety of sensory stimuli is a feature of persistent whiplash associated disorders (WAD). However, little is known about sensory disturbances from the time of injury until transition to either recovery or symptom persistence. Quantitative sensory testing (pressure and thermal pain thresholds, the brachial plexus provocation test), the sympathetic vasoconstrictor reflex and psychological distress (GHQ‐28) were prospectively measured in 76 whiplash subjects within 1 month of injury and then 2, 3 and 6 months post‐injury. Subjects were classified at 6 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). Sensory and sympathetic nervous system tests were also measured in 20 control subjects. All whiplash groups demonstrated local mechanical hyperalgesia in the cervical spine at 1 month post‐injury. This hyperalgesia persisted in those with moderate/severe symptoms at 6 months but resolved by 2 months in those who had recovered or reported persistent mild symptoms. Only those with persistent moderate/severe symptoms at 6 months demonstrated generalised hypersensitivity to all sensory tests. These changes occurred within 1 month of injury and remained unchanged throughout the study period. Whilst no significant group differences were evident for the sympathetic vasoconstrictor response, the moderate/severe group showed a tendency for diminished sympathetic reactivity. GHQ‐28 scores of the moderate/severe group were higher than those of the other two groups. The differences in GHQ‐28 did not impact on any of the sensory measures. These findings suggest that those with persistent moderate/severe symptoms at 6 months display, soon after injury, generalised hypersensitivity suggestive of changes in central pain processing mechanisms. This phenomenon did not occur in those who recover or those with persistent mild symptoms.

Dizziness and unsteadiness following whiplash injury: characteristic features and relationship with cervical joint position error.

Dizziness and/or unsteadiness are common symptoms of chronic whiplash-associated disorders. This study aimed to report the characteristics of these symptoms and determine whether there was any relationship to cervical joint position error. Joint position error, the accuracy to return to the natural head posture following extension and rotation, was measured in 102 subjects with persistent whiplash-associated disorder and 44 control subjects. Whiplash subjects completed a neck pain index and answered questions about the characteristics of dizziness. The results indicated that subjects with whiplash-associated disorders had significantly greater joint position errors than control subjects. Within the whiplash group, those with dizziness had greater joint position errors than those without dizziness following rotation (rotation (R) 4.5 degrees (0.3) vs 2.9 degrees (0.4); rotation (L) 3.9 degrees (0.3) vs 2.8 degrees (0.4) respectively) and a higher neck pain index (55.3% (1.4) vs 43.1% (1.8)). Characteristics of the dizziness were consistent for those reported for a cervical cause but no characteristics could predict the magnitude of joint position error. Cervical mechanoreceptor dysfunction is a likely cause of dizziness in whiplash-associated disorder.

Physical and psychological factors predict outcome following whiplash injury.

&NA; Predictors of outcome following whiplash injury are limited to socio‐demographic and symptomatic factors, which are not readily amenable to secondary and tertiary intervention. This prospective study investigated the predictive capacity of early measures of physical and psychological impairment on pain and disability 6 months following whiplash injury. Motor function (ROM; kinaesthetic sense; activity of the superficial neck flexors (EMG) during cranio‐cervical flexion), quantitative sensory testing (pressure, thermal pain thresholds, brachial plexus provocation test), sympathetic vasoconstrictor responses and psychological distress (GHQ‐28, TSK, IES) were measured in 76 acute whiplash participants. The outcome measure was Neck Disability Index scores at 6 months. Stepwise regression analysis was used to predict the final NDI score. Logistic regression analyses predicted membership to one of the three groups based on final NDI scores (<8 recovered, 10–28 mild pain and disability, >30 moderate/severe pain and disability). Higher initial NDI score (1.007–1.12), older age (1.03–1.23), cold hyperalgesia (1.05–1.58), and acute post‐traumatic stress (1.03–1.2) predicted membership to the moderate/severe group. Additional variables associated with higher NDI scores at 6 months on stepwise regression analysis were: ROM loss and diminished sympathetic reactivity. Higher initial NDI score (1.03–1.28), greater psychological distress (GHQ‐28) (1.04–1.28) and decreased ROM (1.03–1.25) predicted subjects with persistent milder symptoms from those who fully recovered. These results demonstrate that both physical and psychological factors play a role in recovery or non‐recovery from whiplash injury. This may assist in the development of more relevant treatment methods for acute whiplash.

development of motor system dysfunction following whiplash injury

&NA; 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.

Physical and psychological factors maintain long-term predictive capacity post-whiplash injury

Abstract Higher initial levels of pain and disability, older age, cold hyperalgesia, impaired sympathetic vasoconstriction and moderate post‐traumatic stress symptoms have been shown to be associated with poor outcome 6 months following whiplash injury. This study prospectively investigated the predictive capacity of these variables at a long‐term follow‐up. Sixty‐five of an initial cohort of 76 acutely injured whiplash participants were followed to 2–3 years post‐accident. Motor function (ROM; kinaesthetic sense; activity of the superficial neck flexors (EMG) during cranio‐cervical flexion), quantitative sensory testing (pressure, thermal pain thresholds and brachial plexus provocation test), sympathetic vasoconstrictor responses and psychological distress (GHQ‐28, TSK and IES) were measured. The outcome measure was Neck Disability Index (NDI) scores. Participants with ongoing moderate/severe symptoms at 2–3 years continued to manifest decreased ROM, increased EMG during cranio‐cervical flexion, sensory hypersensitivity and elevated levels of psychological distress when compared to recovered participants and those with milder symptoms. The latter two groups showed only persistent deficits in cervical muscle recruitment patterns. Higher initial NDI scores (OR 1.00–1.1), older age (OR 1.00–1.13), cold hyperalgesia (OR 1.1–1.13) and post‐traumatic stress symptoms (OR 1.03–1.2) remained significant predictors of poor outcome at long‐term follow‐up (r2 = 0.56). The robustness of these physical and psychological factors suggests that their assessment in the acute stage following whiplash injury will be important.

Cervical range of motion discriminates between asymptomatic persons and those with whiplash.

Study Design. A comparative study of cervical range of motion in asymptomatic persons and those with whiplash. Objectives. To compare the primary and conjunct ranges of motion of the cervical spine in asymptomatic persons and those with persistent whiplash-associated disorders, and to investigate the ability of these measures of range of motion to discriminate between the groups. Summary of Background. Evidence that range of motion is an effective indicator of physical impairment in the cervical spine is not conclusive. Few studies have evaluated the ability to discriminate between asymptomatic persons and those with whiplash on the basis of range of motion or compared three-dimensional in vivo measures of range of motion in asymptomatic persons and those with whiplash-associated disorders. Methods. The study participants were 89 asymptomatic volunteers (41 men, 48 women; mean age 39.2 years) and 114 patients with persistent whiplash-associated disorders (22 men, 93 women; mean age 37.2 years) referred to a whiplash research unit for assessment of their cervical region. Range of cervical motion was measured in three dimensions with a computerized, electromagnetic, motion-tracking device. The movements assessed were flexion, extension, left and right lateral flexion, and left and right rotation. Results. Range of motion was reduced in all primary movements in patients with persistent whiplash-associated disorder. Sagittal plane movements were proportionally the most affected. On the basis of primary and conjunct range of motion, age, and gender, 90.3% of study participants could be correctly categorized as asymptomatic or as having whiplash (sensitivity 86.2%, specificity 95.3%). Conclusions. Range of motion was capable of discriminating between asymptomatic persons and those with persistent whiplash-associated disorders.

Widespread Sensory Hypersensitivity Is a Feature of Chronic Whiplash-Associated Disorder but not Chronic Idiopathic Neck Pain

Objectives: To investigate sensory changes present in patients with chronic whiplash-associated disorders and chronic idiopathic neck pain using a variety of quantitative sensory tests to better understand the pain processing mechanisms underlying persistent symptoms. Methods: A case control study was used with 29 subjects with chronic whiplash-associated disorders, 20 subjects with chronic idiopathic neck pain, and 20 pain-free volunteers. Pressure pain thresholds were measured over the articular pillars of C2-C3, C5-C6, the median, radial, and ulnar nerve trunks in the arm and over a remote site, the muscle belly of tibialis anterior. Heat pain thresholds, cold pain thresholds, and von Frey hair sensibility were measured over the cervical spine, tibialis anterior, and deltoid insertion. Anxiety was measured with the Short-Form of the Spielberger State Anxiety Inventory. Results: Pressure pain thresholds were decreased over cervical spine sites in both subject groups when compared with controls (P < 0.05). In the chronic whiplash-associated disorders group, pressure pain thresholds were also decreased over the tibialis anterior, median, and radial nerve trunks (P < 0.001). Heat pain thresholds were decreased and cold pain thresholds increased at all sites (P < 0.03). No differencesin heat pain thresholds or cold pain thresholds were evident in the idiopathic neck pain group at any site compared with the control group (P > 0.27). No abnormalities in von Frey hair sensibility were evident in either neck pain group (P > 0.28). Discussion: Both chronic whiplash-associated disorders and idiopathic neck pain groups were characterized by mechanical hyperalgesia over the cervical spine. Whiplash subjects showed additional widespread hypersensitivity to mechanical pressure and thermal stimuli, which was independent of state anxiety and may represent changes in central pain processing mechanisms. This may have implications for future treatment approaches.

Course and prognostic factors of whiplash: a systematic review and meta-analysis.

&NA; We conducted a systematic review and meta‐analysis of prospective cohort studies of subjects with acute whiplash injuries. The aim was to describe the course of recovery, pain and disability symptoms and also to assess the influence of different prognostic factors on outcome. Studies were selected for inclusion if they enrolled subjects with neck pain within six weeks of a car accident and measured pain and/or disability outcomes. Studies were located via a sensitive search of electronic databases; Medline, Embase, CINAHL, Cochrane database, ACP Journal club, DARE and Psychinfo and through hand‐searches of relevant previous reviews. Methodological quality of all studies was assessed using a six item checklist. Sixty‐seven articles, describing 38 separate cohorts were included. Recovery rates were extremely variable across studies but homogeneity was improved when only data from studies of more robust methodological quality were considered. These data suggest that recovery occurs for a substantial proportion of subjects in the initial 3 months after the accident but after this time recovery rates level off. Pain and disability symptoms also reduce rapidly in the initial months after the accident but show little improvement after 3 months have elapsed. Data regarding the prognostic factors associated with poor recovery were difficult to interpret due to heterogeneity of the techniques used to assess such associations and the way in which they are reported. There was also wide variation in the measurement of outcome and the use of validated measures would improve interpretability and comparability of future studies.

The development of psychological changes following whiplash injury

&NA; Psychological distress is a feature of chronic whiplash‐associated disorders, but little is known of psychological changes from soon after injury to either recovery or symptom persistence. This study prospectively measured psychological distress (General Health Questionnaire 28, GHQ‐28), fear of movement/re‐injury (TAMPA Scale of Kinesphobia, TSK), acute post‐traumatic stress (Impact of Events Scale, IES) and general health and well being (Short Form 36, SF‐36) in 76 whiplash subjects within 1 month of injury and then 2, 3 and 6 months post‐injury. Subjects were classified at 6 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). All whiplash groups demonstrated psychological distress (GHQ‐28, SF‐36) to some extent at 1 month post‐injury. Scores of the recovered group and those with persistent mild symptoms returned to levels regarded as normal by 2 months post‐injury, parallelling a decrease in reported pain and disability. Scores on both these tests remained above threshold levels in those with ongoing moderate/severe symptoms. The moderate/severe and mild groups showed elevated TSK scores at 1 month post‐injury. TSK scores decreased by 2 months in the group with residual mild symptoms and by 6 months in those with persistent moderate/severe symptoms. Elevated IES scores, indicative of a moderate post‐traumatic stress reaction, were unique to the group with moderate/severe symptoms. The results of this study demonstrated that all those experiencing whiplash injury display initial psychological distress that decreased in those whose symptoms subside. Whiplash participants who reported persistent moderate/severe symptoms at 6 months continue to be psychologically distressed and are also characterised by a moderate post‐traumatic stress reaction.

Does the presence of sensory hypersensitivity influence outcomes of physical rehabilitation for chronic whiplash? - A preliminary RCT

Abstract Patients with chronic whiplash associated disorders present with varied sensory, motor and psychological features. In this first instance it was questioned whether a multimodal program of physical therapies was an appropriate management to be broadly prescribed for these patients when it was known that some would have sensory features suggestive of a notable pain syndrome. A randomised controlled trial was conducted with 71 participants with persistent neck pain following a motor vehicle crash to explore this question. Participants were randomly allocated to receive either a multimodal physiotherapy program (MPT) or a self‐management program (SMP) (advice and exercise). In the randomisation process, participants were stratified according to the presence or not of widespread mechanical or cold hyperalgesia. The intervention period was 10 weeks and outcomes were assessed immediately following treatment. Even with the presence of sensory hypersensitivity in 72.5% of subjects, both groups reported some relief of neck pain and disability (Neck Disability Index) and it was superior in the group receiving multimodal physiotherapy (p = 0.04). Post‐hoc observations however suggested that relief was marginal in the subgroup with both widespread mechanical and cold hyperalgesia. Further research is required to test the validity of this sub‐group observation and to test the effect of the intervention in the long term.