Hypoesthesia occurs in acute whiplash irrespective of pain and disability levels and the presence of sensory hypersensitivity.

OBJECTIVES

In contrast to the increasing knowledge of the sensory dysfunction involved in chronic whiplash associated disorders, the use of comprehensive quantitative sensory testing in the acute stage of the condition is sparse. In this study, we sought to investigate the presence of sensory hypoesthesia in participants with acute whiplash injury.

METHODS

Fifty-two volunteers within 4 weeks after a motor vehicle accident and 31 healthy asymptomatic volunteers were recruited for this study. We classified our cohort into either a "high-risk" (n=17; signs associated with poor recovery including Neck Disability Index scores >30, cold and mechanical hyperalgesia, heightened brachial plexus provocation test responses) or "low-risk" group (without these signs). Detection thresholds to electrical, thermal, and vibration stimuli measured in lower cervical nerve root innervation zones and psychologic distress and posttraumatic stress symptoms were compared between the groups using multivariate analysis of covariance.

RESULTS

Both the high-risk and low-risk groups exhibited significant elevation in sensory detection when compared with controls (P<0.05). There was no difference in detection thresholds between the 2 whiplash groups, except for electrical detection which was greater in the high-risk group (P>0.05). Both groups were psychologically distressed.

DISCUSSION

Our findings demonstrate generalized hypoesthesia in acute whiplash associated disorders suggesting adaptive central nervous system processing mechanisms are involved, regardless of pain and disability. The elevated levels of psychologic distress seen in both groups may also play a role.