Outcome and prognostic factors of epilepsy surgery in children with focal cortical dysplasia

Abstract

Objective: Focal cortical dysplasia (FCD) is a subgroup of malformations of cortical development, characterized by disorganization of the normal cortical architecture. It is the most common cause of intractable focal epilepsy in children. Antiepileptic medication treatment is often ineffective. Thus, epilepsy surgery is one of the valuable treatment options to achieve seizure freedom in these intractable focal epilepsy patients. We aimed to analyze surgical outcome and prognostic factors of epilepsy surgery in children with focal cortical dysplasia. Methods: Eighty four children who had resective epilepsy surgery from January 2004 to December 2013, histologically proven cortical dysplasia, and a follow-up period of at least 2 years were included. Medical records regarding demographics, epilepsy details, types of FCD, presurgical evaluations, longitudinal analysis of seizure control, and postoperative complications were retrospectively analyzed. Results: The mean age at epilepsy onset was 5.2 years and the mean age at epilepsy surgery was 10.7 years. The mean postoperative follow-up duration was 5.2 years (range 2.2-22.6 years). Patients with FCDⅡ had significantly early onset of epilepsy, higher seizure frequency, and underwent surgery at a significantly younger age compared to the other types. Diagnostic sensitivities of preoperative evaluations were various. Interictal and ictal electroencephalography localized epileptogenic zone with 58-68% accuracy. Magnetic resonance imaging (MRI), fludeoxyglucose-positron emission tomography (FDG-PET), ictal single-photon emission computed tomography (SPECT) had diagnostic sensitivity of 80-90%. Of 84 patients, Engel class I was achieved in 66% of patients at postoperative 1 year, 60% at postoperative 2 year, and 52% at last follow-up. Focal lesion on MRI and complete resection are major prognostic factors for postoperative seizure outcome. Thirty percent of 84 patients had incomplete resection, and the most important reason was overlap of dysplastic cortex and motor cortex. In 45 patients who had postoperative seizures, 84.5% of them had seizure recurrence within postoperative 2 years and the long term seizure-freedom rates remain stable. Fourty-four percent of 84 patients discontinued antiepileptic medication successfully. Conclusion: Postoperative seizure outcome was favorable in children with focal cortical dysplasia with low risk of surgical complications. Comprehensive presurgical evaluations and multidisciplinary team approach would enhance the chance for detecting epileptogenic region associated with cortical dysplasia. Constant and systematic presurgical, or surgical variables to predict postoperative outcome would help selecting the ideal candidate for epilepsy surgery.