FDG-PET and MRI in temporal lobe epilepsy: relationship to febrile seizures, hippocampal sclerosis and outcome.

Objective: To correlate the volumetric head magnetic resonance imaging (MRI) and fluorodeoxyglucose-positron emission tomography (FDG-PET) scan findings with the history, intracarotid amobarbital procedure, pathology, and outcome in patients with medically refractory temporal lobe epilepsy.

Material And Methods: Thirty-eight patients with temporal lobe epilepsy treated surgically following a comprehensive presurgical evaluation. Follow-up ranged from 12 to 44 months.

Results: Volumetric MRI showed ipsilateral hippocampal atrophy in 29 (76%), and PET scan showed ipsilateral temporal hypometabolism (PET-TH) in 31 (81.5%) of patients. Eighty-three percent of those patients with hippocampal sclerosis on MRI (MRI-HS) had ipsilateral PET-TH. Sixty-six percent of patients with MRI-HS had a history of prolonged febrile convulsions or a childhood febrile illness accompanied by convulsions, and 77% of patients with MRI-HS had pathologically proven hippocampal sclerosis (HS). Ninety percent became seizure free or had rare seizures.

Conclusion: FDG-PET scans and head MRIs were complementary; 95% of patients had either MRI-HS or temporal hypometabolism. MRI-HS correlated with a history of febrile seizures and pathologically demonstrated hippocampal sclerosis. Ninety-three percent of patients had focal functional deficits on the epileptogenic side. Concordance between PET temporal hypometabolism and MRI-HS correlated with better outcome.