A patient with juvenile myoclonic epilepsy (JME), manifested as absences at age 10 and myoclonic jerking and generalized tonic clonic seizures at age 15, was treated successfully with primidone at the King Fahad National Guard Hospital, Riyadh, Saudi Arabia. Absence seizures were provoked by thyroxine 50 mcg daily prescribed at age 35 for a simple goitre associated with normal thyroid function tests. Loss of concentration lasting a few seconds was associated with frequent discharges of sharp, spike, multispike, and slow wave complexes on the EEG. The thyroid levels were slightly elevated compared to initial tests. Absences stopped and the EEG returned to normal after thyroxine was discontinued. 
COMMENT. When thyroid hormone is administered in patients with epilepsy, the dose should be monitored carefully and an EEG obtained to examine for subclinical absence seizures requiring additional antiepileptic medication.