Thyroxine-induced hypermotor seizure.

Thyroxine-induced epilepsy is a very rare condition occurring in epileptic patients. Here we report a boy with thyroxine-induced hypermotor seizure (HMS) following thyroxine administration for his central hypothyroidism secondary to surgery and cranial radiation for his brain tumor. After 3 years seizure-free period, he had repeated HMS, seven to eight attacks per day, after initiation L-thyroxine treatment. Following reduction of the daily thyroxine dose, his seizures decreased in frequency. To our knowledge, this is the first reported case of HMS associated with L-thyroxine administration.