[Congenital Minamata disease accompanied by arachnoid cyst (author's transl)]

A male, born on December 8, 1956, during the period when many Minamata diseases broke out in a district. His parents who ate much fish and shell fish taken in Minamata Bay suffered from the light, incomplete Minamata disease showing sensory disturbance, the constriction of the visual field, muscular weakness, etc. He weighed 3,225 gr. upon the normal birth given 10 months after pregnancy. His abnormalities were noted since his head was not stabilized on the neck even six months after the birth. Because of the delay in the development of the motor function, he became barely able to sit, stand up and begin walking at the ages of 3, 5 and 6 respectively. In 1962 (at the age of 6), his congenital Minamata disease was diagnosed in view of his clinical symptoms and epidemiological conditions. The mercury value in the hair and blood upon the birth is not known because a considerable time had elapsed after the birth when his mercury poisoning was discovered. However, the clinical symptoms included intelligence disturbance, character change, dysarthria, primitive reflexes, strabismus, hypersalivation, ataxia and hyperkinesia, indicating a typical congenital Minamata disease. Until he became 13 years old (1969) or so, his mental and motor function developed, both gradually. In the same year, he was admitted to a special class for the handicapped. EEG examination revealed that there was a slow alpha activity in the basic pattern and that 6 Hz positive spike was found in the sleep EEG. The constriction of the visual field was classified through examination.2+