Assessment of cerebellar, vestibular and spinocerebellar effects of various factors using posuturography

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To examine the effects of occupational and environmental factors such as lead, organic solvents (n-hexane, xylene and toluene) and sarin on vestibular, cerebellar and spinocerebellar afferent system using a computerized posturography with sway frequency analysis. The following three groups of subjects were examined : (1) 49 male chemical factory workers exposed to lead stearate, aged 27-63 (mean 43) years, with concurrent blood lead concentrations (BPhs) of 11-113 (mean 48) mug/10Og and past mean BPbs of 7-52 (mean 24) mug/100g ; (2) 29 male sandal, shoe and leather factory workers, aged 35-73 (mean 51) years, with urinary concentrations of 2,5-hexanedione (HD) of 0.41-3.06 (mean 1.20) mg/g creatinine ; and (3) 9 males and 9 females, aged 19-58 (mean 31) years, who exposed to accidentally sarin by a presumed terrorist attack (Tokyo Subway Sarin Poisoning, March 20, 1995) and showed plasma cholinesterase (ChE) of 13-131 (mean 72) IU/1 6-8 months before the study. Control subjects for th … More e three groups were "healthy" volunteers composed of (1) 23 males, (2) 22 males, and (3) 31 males and 24 females, respectively. Postural balance was measured using a force platform connected to a microcomputer. Power of the sway for each frequency domain was calculated by the FFT method ; length and area of the sway path were measured ; and Romberg quotients (RQs, eyes-closed to eyes-open ratios) for each sway measures were determined.In lead workers, the postural sway of high (2-4 Hz) and low (0-1 Hz) frequencies with eyes open and closed were significantly increased. The sway of 0.5-2 Hz with eyes open was significantly related to concurrent BPb ; whereas the sway of high frequency with eyes closed was related to past mean BPb. In organic solvent workers, the high frequency sway with eyes closed was significantly increased ; 1-4 Hz sway with eyes open was related positively to HD and inversely to methylhippurinc acid concentrations in urine. In female sarin poisoning patients, low frequency sway with eyes open was significantly increased. RQs for low frequency sway were significantly correlated with log ChE in both male and female poisoning patients.The pattern of the posturographic changes suggested that the vestibulo- cerebellum, anterior cerebellar lobe and spinocerebellar afferent were asymptomatically affected by lead ; the vestibulo-cerebellar change reflected concurrent lead absorption and the anterior cerebellar one reflected past absorption. Similarly, the vestibulo-cerebellar and spinocerebellar afferent function was affected by n-hexane ; the effect on vestibulo-cerebellar function was possibly inhibited by xylene. The chronic (long-term) vestibulo-cerebellar effect was considered to be induced by acute sarin poisoning ; females might be more susceptible than males. The computerized posturography with frequency analysis seems useful for assessment of vestibular, cerebellar and spinocerebellar afferent function. Less