VESTIBULAR FUNCTION-TEST ANOMALIES IN PATIENTS WITH CHRONIC FATIGUE SYNDROME

Chronic fatigue syndrome (CFS) is distinguished by the new onset of de bilitating fatigue that lasts at least 6 months, concomitant with othe r symptoms to be described later. Many CFS patients complain of disequ ilibrium, yet the exact type of the balance dysfunction and its functi on and its location (peripheral vs. central) have not been described. Herein we report results of vestibular function testing performed on 1 1 CFS patients. These results revealed no predominant pattern of abnor malities. Patients typically performed below average in dynamic postur ography testing, with a significant number of falls in the tests requi ring subjects to depend heavily on the vestibular system. One patient had abnormal caloric testing, while 3 had abnormally low earth vertica l axis relation (EVA) gains at the higher frequencies tested. As a gro up, the average gain of EVA was significantly lower than normals in th e 0.1-1.0 Hz range (p < 0.05). In earth horizontal axis rotation, the CFS group had a higher than normal bias value for the optokinetic (OKN ) and eyes open in the dark conditions (p < 0.05), but had normal scor es during visual vestibular reflex testing. Five of the 11 subjects ha d an abnormal OKN bias build up over the course of the run, equal to o r actually exceeding the 60 degrees/s target velocity by as much as 14 degrees/s. Altogether, these results are more suggestive of central n ervous system deficits than of peripheral vestibular disfunction.