Abstracts

Temporal lobe epilepsy surgery (TLES) benefits [gt] 80% of patients, and normalizes the late mortality rate in patients who become seizure free (Salanova et. al. Epilepsia 2002). Few centers have analyzed patients who continue to have seizures. Our purpose was to analyze the reason for surgical failures and the role of reoperation and to compare these patients with seizure free patients, to see if there were significant differences between the groups.
From 1984-2002, 262 patients with TLE underwent surgery following a comprehensive presurgical evaluation . There was no surgical mortality. Patients were followed at 3, 6 and 12 months and yearly therafter. 65% became seizure free (class I), 19% had rare seizures, (class II ) and 16% continued to have seizures (class III, IV). Patients with persistent seizures (class III, IV) underwent re-evaluation to include prolonged Video-EEG recordings and MRIs .The clinical history, seizure type, post surgical MRI, pathology, types of resections, outcome , the reasons for failure and the late mortality rate were analyzed, and compared with those patients who became seizure free.
Analysis of failures (41pts, class III, IV) : Mean age of seizure onset was 11 yrs, mean age at surgery 26.6 yrs, and mean duration of epilepsy 15.2yrs. 12% had febrile seizures (FS), 29% head trauma, and 7% encephalitis. 56% had epigastric or experiential auras, 52.5% had abnormal imaging, 34% bitemporal interictal epileptiform discharges, and 20% posterior temporal localization. 84% had a pathological diagnosis and 18% had dual pathology. Post-surgical MRI showed residual posterior mesial temporal structures (PMTS) in 26/30 (86.6%), residual PMTS and posterior temporal lesions (PTL) in 2 (6.6%), and PTLs in 2 (6.6%). The recorded temporal lobe seizures were localized to the side of the previous resection. 21 patients underwent reoperation (11 on the left ). 14 had resection of the posterior MTS, 5 of the posterior MTS and basal posterior temporal cortex, and 2 of the posterior MTS and PTLs. There was no surgical mortality .57% became seizure free and 24% had rare seizures. We compared these patients with those seizure free, and found that 45% of seizure free patients had FS, 12% had head trauma , and 70% had abnormal imaging, Fewer seizure free patients had invasive recordings, and the late mortality late was lower than in those patients with persistent seizures.
When compared to seizure free patients, patients who failed temporal lobe epilepsy surgery were less likely to have a history of FS and abnormal imaging, and more likely to have a history of head trauma, encephalitis, and posterior temporal localization, suggesting larger epileptogenic zones. 57% became seizure free following resection of the posterior MTS and posterior basal temporal cortex. Patients who fail surgery should be reevaluated for reoperation .