The role of positron emission tomography in the evaluation of seizure disorders.

We studied patients with partial and primary generalized seizures using fluorine-18-labeled 2-fluorodeoxyglucose and positron emission tomography. Interictal studies of patients with partial seizures showed regions of focal or lateralized hypometabolism in 15 of 17 patients with unilateral electroencephalographic foci. Several patients had more than one hypometabolic region. In 1 patient PET hypometabolism was contralateral to the electroencephalographic epileptic focus. Six of 10 patients without definite electroencephalographic foci also showed unilateral PET hypometabolic regions. PET during complex partial seizures in 3 patients showed hypermetabolism at the site of the hypometabolic focus. A postictal scan in 1 patient showed extension of interictal temporal hypometabolism to the frontal lobe as well. Interictal scans in 8 patients with primary generalized seizures did not reveal any hypometabolic regions. One patient scanned during an attack of absence status epilepticus showed a slight decrease in metabolic rate compared to the interictal scan. Temporal lobectomy has been performed in 6 patients with focal PET hypometabolism. PET may obviate the need for depth electrode study in some patients with intractable partial seizures.