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.