Electroencephalographic, volumetric, and neuropsychological indicators of seizure focus lateralization in temporal lobe epilepsy

Context: Anterior temporal lobectomy is an effective treatment for medicall y intractable temporal lobe seizures. identification of seizure focus is es sential to surgical success. Objective: To examine the usefulness of presurgical electroencephalography (EEG), magnetic resonance imaging (MRI), and neuropsychological data in the lateralization of seizure focus. Design: Presurgical EEC, MRI, and neuropsychological data were entered, ind ependently and in combination, as indicators of seizure focus lateralizatio n in discriminant function analyses, yielding correct seizure lateralizatio n rates for each set of indicators. Setting: Comprehensive Epilepsy Progam, Shands Teaching Hospital, Universit y of Florida, Gainesville. Patients: Forty-Tour right-handed adult patients who ultimately underwent s uccessful anterior temporal lobectomy. Left-handed patients, those with les s-than-optimal surgical outcome, and ally patients with a history of neurol ogical insult unrelated to seizure disorder were excluded from this study. Main Outcome Measures: For each patient presur gical EEG was represented as a seizure lateralization index reflecting the numbers of seizures originat ing in the left hemisphere, right hemisphere, and those unable to be latera lized. Magnetic resonance imaging data were represented as left-right diffe rence in hippocampal volume. Neuropsychological data consisted of mean scor es in each of 5 cognitive domains. Results: The EEG was a better indicator of lateralization (89% correct) tha n MRI (86%), although not significantly. The EEG and MRI were significantly superior to neuropsychological data (66%) (P=.02 and .04, respectively). C ombining EEG and MRI yielded a significantly higher lateralization rate (93 %) than EEG alone (P<.01). Adding neuropsychological data improved this sli ghtly (95%). Conclusions: The EEG and MRI were of high lateralization value, while neuro psychological data were of limited use in this regard. Combining EEG, MRI, and neuropsychological improved focus lateralization relative to using thes e data independently.