[Petit mal status in hyperthyroidism].

A 68-year-old woman who, for the first time, had a generalized tonic-clonic seizure and persisting confusional state was found to have nodular enlargement of the thyroid and a tachycardic arrhythmia. Electroencephalography (EEG) demonstrated a continuous irregular polyspike wave pattern. Total T4 concentration was elevated to 23 micrograms/dl. Consecutive Administration of 250 mg phenytoin, 4 mg clonazepam and 7.5 mg midazolam changed neither the clinical nor the EEG findings. But after general intensive care measures and high-dose thyrostatic treatment (40 mg thiamazole intravenously every four hours) the clinical and neurological status became normal. Serial EEGs over the subsequent weeks and months showed gradual disappearance of the abnormal changes with increasingly prolonged periods of normal activity.