EVALUATION OF NEUROLOGIC FUNCTION IN GULF-WAR VETERANS - A BLINDED CASE-CONTROL STUDY

Objective.-To determine whether Gulf War-related illnesses are associa ted with central or peripheral nervous system dysfunction. Design.-Nes ted case-control study. Participants.-Twenty-three veterans with facto r analysis-derived syndromes (the cases), 10 well veterans deployed to the Gulf War (the deployed controls), and 10 well veterans not deploy ed to the Gulf War (the nondeployed controls), Method.-With investigat ors blinded to group identities, participants underwent objective neur ophysiological, audiovestibular, neuroradiological, neuropsychological , and blood tests. Main Outcome Measures.-Evidence of neurologic dysfu nction. Results.-Compared with the 20 controls, the 23 cases had signi ficantly more neuropsychological evidence of brain dysfunction on the Halstead Impairment Index (P=.01), greater interside asymmetry of the wave I to wave III interpeak latency of brain stem auditory evoked pot entials (P=.02), greater interocular asymmetry of nystagmic velocity o n rotational testing, increased asymmetry of saccadic Velocity (P=.04) , more prolonged interpeak latency of the lumbar-to-cerebral peaks on posterior tibial somatosensory evoked potentials (on right side, P=.03 , and on the left side, P=.005), and diminished nystagmic velocity aft er caloric stimulation bilaterally (P values range from .02 to .04). C ases (n=5) with syndrome 1 (''impaired cognition'') were the most impa ired on brain stem auditory evoked potentials (P=.005); those (n=13) w ith syndrome 2 (''confusion-ataxia'') were the most impaired on the Ha lstead Impairment Index (P=.006), rotational testing (P=.01), asymmetr y of saccadic velocity (P=.03), and somatosensory evoked potentials (P less than or equal to.01); and those (n=5) with syndrome 3 (''arthro- myo-neuropathy'') were the most impaired on caloric stimulation (P les s than or equal to.01). Conclusions.-The 3 factor-derived syndromes id entified among Gulf War veterans appear to represent variants of a gen eralized injury to the nervous system.