Of nineteen autopsy cases of the severely handicapped, histological findings of the brain were correlated with background activities of the scalp EEG. Histological investigation was predominantly concentrated on the cerebral hemispheres, thalamus and tegumentum of the brain stem in the present report. 1) No rhythmic activity was observed in cases with severe lesions in the hemispheres or nonspecific thalamic nuclei (centre median and intralaminar nuclei). This fact suggests nonspecific thalamo-cortical circuit is likely to play an important role for rhythm formation of EEG. 2) Alpha activity is observed in patients with intact or slightly damaged hemispheres, nonspecific thalamic nuclei and mesencephalic and pontine teugmentum. To be compatible with previous reports of alpha rhythm recorded from coma patients with the brain stem lesion, it is discussed that the background of mesencephalic reticular activity may be required for the presence of alpha wave. 3) Spindle activity in sleep was not presented in cases with lesions in the hemispheres and nonspecific thalamic nuclei. Thus spindle formation may be based on the nonspecific thalamo-cortical circuit as well. Hump pattern in sleep is, in general, less observed than normal. 4) In cases who showed a predominant background activity of rhythmic fast pattern intact nonspecific thalamic nuclei and lesions in the hemispheres were observed. It is, therefore, assumed that the presence of some residual activity of nonspecific thalamic nuclei and of dysfunction of the hemispheres are required to generate the rhythmic fast activity. 5) Lesions in specific thalamic nuclei were not apparent electroencephalographically within the extent of the present investigation. 6) Amplitude of EEG appeared to have no correlation with neuropathological findings but one case with a flat pattern that was severely damaged in both hemispheres. 7) In general, localized flat pattern or slow activity showed the locus of the lesion in the hemispheres. However many other cases still failed to show the focal finding in EEG whereas they had the localized lesion there. This fact suggests some components of scalp EEG attribute to propagtaion of subcortical electrical activities.
Twenty three patients with congenital Minamata disease were borned from 1953 to 1962 in mina-mata district of Japan. Three cases of them were dead. The cause of the disease was organic mercury poisoning in fetus period. Their clinical signs revealed the feature of mixed or unclassified type of cerebral palsy. Severe generalized ataxia, dyskinesia, dysarthria, incoodination of motor, sensory disturbance and mental retardation were observed in almost all patients. The constriction of visual field was noticed in adults and children with Minamata disease, but it had not been clear in congenital cases because of their mental retardation. However, we could examine the visual field in 5 mild cases whose I. Q level ranged between 40-60, but the other cases remained une xamined. Examination of visual field of 4 out of 5 cases revealed the concentric constriction. Motility electrooculogram showed abnormal level in these 5 cases.