Abstracts

Video-EEG monitoring of patients with unilateral mesial temporal sclerosis (uMTS) may show ipsi or contralateral seizure onset in relation to the lesion observed on magnetic resonance imaging (MRI). Contralateral seizure onset usually determines invasive monitoring to evaluate seizure onset side. Contralateral seizure onset on invasive monitoring may contraindicate surgery. We evaluated long term seizure control after anteromesial temporal lobectomy (AMTL) in two groups of uMTS patients: patients with seizure onset concordant and patients with discordant seizure onset. All patients were uniformly submitted to AMTL on the MTS side without undergoing invasive monitoring. Retrospective evaluation of the surgical prognosis of all uMTS patients who underwent AMTL in our epilepsy surgery group between January 1999 and June 2004. We analyzed seizure onset side for all video-EEG recorded seizures and compared seizure onset side to MRI lesion side. Concordant cases were defined as all seizures originating, on scalp EEG, ipsilaterally to the MTS (Group 1). Discordant cases were defined as at least one seizure originating contralaterally to the MRI verified MTS (Group 2). Good surgical prognosis (GP) was defined as Engel[apos]s class I. All cases were uniformly submitted to AMTL on the lesion side, without undergoing invasive monitoring. Sixty patients with uMTS were operated in that period. One patient with postoperative psychogenic seizures was excluded from analysis. In five other patients (all in the concordant group) followup data was not obtainable. Of the 54 remaining patients, 31 were men (57,4%), 25 (46,3%) had left MTS, mean age at surgery was 35,7+/-9,6 years (range 14-60), mean postoperative followup was 37,4+/-16,6 months (range 7-68). 40 patients had concordant (Group 1) and 14 had discordant data (Group 2). Long term followup was comparable in both groups (Group 1: 37,0+/-17,0, median 39 vs Group 2: 38,3+/-15,9, median 43 months). Surgical prognosis was similar in both groups (GP: Group 1 - 32/40 or 80% vs. Group 2 - 13/14 or 92,8% p=NS). In this case-control study of uMTS patients submitted to AMTL without invasive monitoring, surgical prognosis was not influenced by video-EEG seizure onset contralateral to the MRI observed lesion. Our findings suggest that a potentially risky procedure such as invasive monitoring may not only not be indicated in this patient population, but may also lead to patients erroneously being denied surgery. (Supported by FAPESP (Sao Paulo State Research Support Foundation).)