Abstracts

Selection of epilepsy surgical candidates requires the analysis of many variables with an objective to identify those patients likely to significantly benefit with minimal complication. This retrospective review strengthens identified predictive trends between diagnostic variables and outcome. We analyzed all pediatric patients who underwent initial resective surgery at Minnesota Epilepsy Group, PA from Jan 2000-Dec 2002. Seizure semiology, ictal/interictal scalp EEGs, and MRIs were analyzed. Sub-dural ictal/inter-ictal EEG, neuropsychological testing, MRS, SPECT, and PET with glucose, alpha-methylol-L-tryptophan, and flumazenil isotopes were reviewed if obtained in the evaluation. Diagnostic abnormalities were characterized by their lateralization/location in the frontal, temporal, parietal or occipital lobe. Findings were categorized by support, neutrality or conflict with the region of resection. Neutral findings were ipsilateral, but not within the region of resection. Any diffuse or contralateral abnormality to the region of resection was defined as a conflicting variable. Diffuse cognitive dysfunction was excluded. Patients were scored at follow-up at 6-, 12-, 24-months by Engel classification, percent seizure reduction, change in neuropsychological status, and complication. Forty-six consecutive subjects were identified and reviewed; 23 (50%) underwent temporal lobe only resection; extra-temporal resections included 10 (22%) frontal, 1 (2%) parietal, and 12 (26%) multi-lobe. In subjects with available follow-up data, 23/41(56%) were seizure free at 12-months and 19/33 (58%) were seizure free at 24-months. Of subjects with [lt]2 conflicting variables, 22/30 (73%) at 12 months and 19/27 (70%) achieved seizure freedom. Subjects with [lt]2 conflicting diagnostic variables were significantly more likely have beneficial outcome of Engel I or II at 12 months (27/30: 90%, p[lt] 0.001) and 24-months (24/27: 89%, p[lt]0.001) by Fischer[apos]s Exact Test. None of the six individuals with two or more conflicting variables attained Engel I or II outcome at 24 months. Supporting and neutral variables did not differ between the outcome groups. A presurgical evaluation with less than two contralateral or diffuse diagnostic abnormalities improves prediction of Engel I-II outcome from 68-90% at 12 months. Only 9% of subjects with two or more conflicting abnormalities achieved Engel I-II at 12 months; none of the subjects maintained that success at 24 months.