Abstracts

RATIONALE: Temporal lobe epilepsy (TLE) has heterogenous pathological substrates. The purpose of this study is to correlate and compare the pathological substrates and surgical outcome in patients with TLE. METHODS: We selected 143 patients who underwent temporal lobectomies and were followed up for more than 1 year. Patients were classified into four groups depending upon the pathological findings: Group 1; mesial temporal sclerosis (MTS) only (n=66), Group 2; MTS + neocortical gliosis (n=29), Group 3; dual-pathology (MTS + cortical dysplasia)(n=28), and Group 4; cortical dysplasia without MTS (n=20). Each pathological group was compared and correlated with surgical outcome. In addition, other clinical variables including age of seizure onset, duration of epilepsy, age at operation, and EEG findings were also statistically analyzed using ANOVA and ?2 tests to determine the prognostic significance. RESULTS: Excellent surgical outcome (Engel's Class 1) was achieved in 58 patients (88%) in Group 1, 25 (86%) in Group 2, 20 (71%) in Group 3, and 11 (55%) in Group 4. Better surgical outcome was observed Group 1 and 2 which had pathological substrates of MTS or neocortical gliosis. Conversely, seizure outcome was worse in Group 3 or 4 which were associated with cortical dysplasia (P = 0.014). There was no significant difference in seizure outcome between Group 1 and 2, and also between Group 3 and 4. Other variables was not statistically correlated with surgical outcome. MRI was helpful to identify cortical dysplasia in only 2 patients (7%) in Group 3 and 4(20%) in Group 4. CONCLUSIONS: Nature of pathological substrate is considered to be the most important factor in determining the surgical outcome in temporal lobe epilepsy surgery. The presence of MTS w/wo neocortical gliosis is directectly related with favorable outcome. However, presence of cortical dysplasia is likely to decrese the chance of seizure freedom.