Seizure outcomes following multilobar epilepsy surgery

Abstract

Outcomes following unilobar surgeries for refractory epilepsy have been well described. However, little is known about long-term seizure outcomes following multilobar resections. The aim of the current study was to identify long-term seizure control and predictors of seizure recurrence in this patient population. Records of patients who underwent multilobar epilepsy surgery at the Cleveland Clinic between 1994 and 2010 were retrospectively reviewed. A postoperative follow-up of at least 6 months was required. Patients were classified as seizure free if they achieved an Engel class I at last follow-up. Long-term chances of seizure freedom were illustrated using a survival analysis, and predictors of recurrence were identified using Cox proportional hazard modeling. Sixty-three patients with medically intractable epilepsy underwent multilobar surgical resections during the study period (mean follow-up of 4.6 years). Predominant resection types included extended occipital (temporoparietooccipital, parietooccipital, temporooccipital: 57%), frontotemporal (21%), and temporoparietal (17%). Mean age at surgery was 21.4 years and mean age at seizure onset was 10.1 years. Fifty-six percent of the patients underwent extraoperative invasive electroencephalography (EEG) evaluations. At 6 postoperative months, 71% (95% confidence interval (CI) 65-77) were seizure-free (SF), 64% (CI 58-70) were SF at 1 year, 52% (CI 46-59) were SF at 5 years, and 41% (CI 32-50) remained SF at 10 years. Forty-one patients had at least one breakthrough seizure after surgery (median timing of recurrence 6.1 months), with an Engel class 1 achieved again by last follow-up in 12 of these 41 cases. Nine patients required a reoperation. Patients who underwent extended occipital/posterior quadrant resections had more favorable outcomes as compared to the other groups. With multivariate analysis, the type of resection (p = 0.03), preoperative auras (p = 0.03), an incomplete resection (0.03), and the presence of postoperative spikes (p = 0.0003) correlated with seizure recurrence. The risk of seizure recurrence for an incomplete resection was 2.3 (CI 1.53-3.36), preoperative aura 2.3 (CI 1.34-3.87), and postoperative spikes on surface EEG 2.5 (CI 1.29-4.71). A favorable outcome can be achieved in 41% of patients undergoing multilobar resections for epilepsy surgery at 10 years of follow-up. Close to one-third of patients who have breakthrough seizures after surgery are able to regain seizure freedom by last follow-up. Predictors of recurrence include resection type (frontotemporal and parietotemporal resections did worse), presence of preoperative aura, an incomplete surgical resection, and the presence of postoperative interictal discharges on EEG.