BILATERAL TEMPORAL HYPOMETABOLISM IN EPILEPSY

Purpose: Positron emission tomography (PET) has proven useful in epile psy surgery for its ability to identify unilateral temporal hypometabo lism (UTH), which is predictive of good surgical outcome. The signific ance of bilateral temporal hypometabolism (BTH) is not known. Methods: We identified all patients who had marked bilateral reduction in temp oral lobe metabolism relative to the cerebellar hemispheres and compar ed their clinical features and treatment outcomes with those of contro l patients with UTH. Results: BTH was evident in 10% of PET scans for epilepsy at our institution. We compared these patients with age-match ed controls with UTH. The BTH patients had a higher percentage of gene ralized seizures; were more likely to have bilateral, diffuse or extra temporal seizure onsets; and had bilateral or diffuse magnetic resonan ce imaging (MRI) findings. UTH patients were more likely to have unila teral mesial temporal atrophy on MRI. Even when electrical seizure ons ets were well localized, surgical outcomes were markedly worse in thes e patients than in controls. Medical treatment was also less successfu l. Social and cognitive functioning was worse in the BTH group. The on ly death occurred in the group with BTH. Conclusions: Patients with BT H have features distinct from those with UTH and have a worse prognosi s for seizure remission after surgery.