Abstract
Two patients with mental deficiency born in 1956 and 1958 in Minamata city were reported. Idiocy, dysarthria, athetosis, chorea, paroxysmal symptoms and clumsiness of movements were observed in either of these patient. In Case 2, strabismus and hypersalivation were also found.
The patients were diagnosed as exogenic mental deficincy.
They were born at the area and during the period of the outbreak of the congenital Minamata disease. The mothers of the patients had eaten a lot of fish or shell-fish contaminated by methyl mercury compounds, and presented some symptoms of the Minamata disease. Any other cause of the disease could not be found in their life history.
Although the neurological symptoms and motor disturbances in the patients were milder than those in the previously reported congenital Minamata disease cases, I conclude that the mental deficiency in these patients were caused by methyl mercury, which had affected during the fetal period. This fact seems to suggest that some mild or atypical cases of the congenital Minamata disease may appear clinically as mental deficiency only.
Finally, the diagnosis of the congenital Minamata disease was discussed.
