Electroencephalographic abnormalities in homocystinuria due to cystathionine synthase deficiency.

Nineteen homocystinuric patients--13 children and 6 adults--were identified in the course of a selective screening for homocystinuria due to cystathionine synthase deficiency. Treatment with high doses (300-1200 mg/day) of pyridoxine was carried out in 17 patients, of whom 15 were completely responsive. In 10 patients EEG abnormalities were observed consisting mainly of a mild diffuse non specific slowing of background activity. In two sisters, with no history of seizures, focal paroxymal activity was also recorded. EEG recordings before and after B6 treatment were available in 16 patients, one of whom was a non responder, during treatment seven normal and six abnormal EEGs showed no change whereas three previously abnormal EEGs were classified as normal.