[A case of chronic methyl bromide intoxication showing symmetrical lesions in the basal ganglia and brain stem on magnetic resonance imaging].

A 30-year-old man developed paresthesia in the feet, unstable gait and blepharoptosis subsequent to pharyngeal pain while working in a warehouse of imported fruit and vegetable fumigated with methyl bromide and cyanate. Neurological examination showed bilateral blepharoptosis, diplopia, ataxic gait and paresthesia below the inguinal region. The serum concentration of thiociane, a metabolite of cyanide, was within normal limits, but that of bromide was elevated (43.7 mg/l, normal: 3.7-8.6). Thus we diagnosed the patient as intoxication of methyl bromide. Magnetic resonance imaging of the brain (MRI) revealed bilateral symmetrical lesions of high signal intensity in the posterior region of the putamen, the subthalamic nuclei, the dorsal medulla oblongata corresponding to inferior cerebellar peduncles and vestibular nuclei, the inferior colliculi and the periaqueductal gray matter surrounding the oculomotor nucleus of the midbrain. As far as we know, this is the first report of MRI detected cerebral lesions in a case with intoxication of methyl bromide.