NEUROLOGIC FEATURES OF CHRONIC MINAMATA DISEASE (ORGANIC MERCURY-POISONING) CERTIFIED AT AUTOPSY

To better understand the neurologic events related to chronic Minamata disease (organic mercury poisoning:), we studied data from 77 patient s with Minamata disease as certified at autopsies performed from 1976 to 1994 (mean age: 72.3 years). Major neurologic findings included: se nsory impairment in 80.5% of the patients which was limited to the ext remities in 42.9%, Impairment of lower extremity coordination was pres ent in 35.8% of the patients,constriction of the visual fields in 28.8 %, and retrocochlear hearing loss in 15.3%. There was no correlation b etween the degree of cerebellar incoordination and the methylmercury c oncentration in the cerebellum. Compared with the classic type of Mina mata disease, the incidence of major neurologic findings was markedly decreased. In light of these findings, supplemental examinations inclu ding brain computed tomography (CT), magnetic resonance imaging (MRI), short latency somatosensory evoked potential (SSEP), or tremogram may be necessary to clinically diagnose Minnmata disease, especially in a typical or mild cases.