Rational and objective: The purpose of this study is to evaluate the relation between a focus of temporal lobe hypometabolism, including comparison between mesial and lateral asymmetry on fluorine-18-labeled-deoxyglucose-positron emission tomography (18FDG-PET) and surgical outcome in patients with uncontrolled partial seizures.
Methods: Case histories, electroencephalogram (EEG) findings, radiographic findings, and surgical outcome (36 +/- 11 months of follow-up) were reviewed in 38 consecutive patients who had a interictal 18FDG-PET scan and subsequent temporal resection.
Results: Among the 36 patients who had a temporal lobe focus of hypometabolism (more than 15% asymmetry to contralateral side), 61% (22 of 36) became seizure-free, 33% (12 of 36) markedly improved and 6% (2 of 36) did not improve. The focus of hypometabolism on PET was in agreement with the epileptic focus on the noninvasive EEG in 30 of 36 patients and in 19 of the 22 patients who underwent an invasive EEG. The asymmetry index for the mesial temporal lobe was significantly higher in the group of patients who became seizure-free compared with the other patients.
Conclusion: This study confirms that a focus of interictal temporal hypometabolism on PET is associated with marked improvement of seizure control after surgery in 94% (34 of 36) of the patients. Hypometabolism in the mesial temporal lobe appears to be associated with a seizure-free outcome.