Abstracts

Rationale: Resective epilepsy surgery has been shown to have up to 70-80% success rates in patients with intractable seizure disorder. Around 20-30% of patients with Engel Classification III and IV will require reevaluation for further surgery. Common reasons for first surgery failures include incomplete resection of seizure focus, incorrect identification of seizure focus and recurrence of tumor. Methods: Clinical chart review of 19 patients from a single adult comprehensive epilepsy program who underwent reoperation from 2007 to 2014 was performed. High resolution Brain MRI, FDG-PET, Neuropsychometric testing were completed in all cases in both the original surgery and the second procedure. Postoperative outcomes were confirmed by prospective telephone follow up and verified by review of the patient's electronic medical records. Outcomes were classified according to the modified Engel classification system: Engel classes I and II are considered good outcomes. Results: A total of nineteen patients (11 males, 8 females) underwent reoperation for resective epilepsy surgery during the study period. The average age of patients at second surgery was 37 years. Reasons for reoperation include: incomplete first resection (n=14) and recurrence of tumor (n= 5) The recurrence of tumor was confirmed with serial brain imaging. The median time between the first and second surgery was 60 months. A majority of patients evaluated for reoperation had focal dyscognitive seizures, with the right temporal lobe being the seizure onset zone. After the second surgery, six of nineteen patients (31.5%) experienced seizure freedom (Engel Cass I). Of the six patients who were Engel Class I, three required extension of the previous resection margins, while two had recurrence of previous tumor. Four of nineteen patients (21%) are classified as Engel Class II. Three patients were lost to follow-up after reoperation. Success rates from reoperation were higher in those with recurrence of tumor. Postoperative complications were recorded in only one case and consisted of an abscess and subdural fluid collection. Despite this complication a good outcome was recorded 12 months later (Engel class II). Conclusions: A recent cumulative review of case series reported in literature records repeat surgery rate of 4-14% of patients, of these 36.6% reported seizure freedom (Surges and Elger, 2013). Our cohort includes more patients that have been recently operated, and our success rate of 31.5% with Engel Class I is similar to that previously reported. The risk of complications from reoperation is low. Our data demonstrates that in patients with medically refractory focal seizures that fail resective epilepsy surgery, reevaluation for repeat surgery is justified.