Early resective surgery causes favorable seizure outcome in malformations of cortical development

Abstract

Purpose: We analyzed consecutive cases of a large cohort of the spectrum of malformations of cortical development (MCDs) including focal cortical dysplasias (FCDs) who underwent presurgical evaluation through our epilepsy program from January 2000-December 2010. We analyzed factors predicting surgical candidacy, predictors of seizure outcome and reasons for deferring surgery.

Methods: 148 patients with MCD underwent detailed presurgical evaluation and 69 were operated. MCD was diagnosed based on characteristic findings in MRI and re-confirmation by histopathology in operated patients. Post-operative seizure outcome of non-operated and operated patients were assessed every 3 and 12 months and yearly intervals. Multivariate analysis and backward step-wise logistic regression analyzed factors predicting seizure outcome. Kaplan-Meier analysis predicted seizure-free survival rates.

Results: 66.67% patients were seizure-free and aura-free at last follow-up. On multivariate logistic regression, the predictors of seizure freedom in operated MCDs were completeness of resection (odds ratio 8.2; 95% CI 1.43-64.96, p=0.01), shorter duration of epilepsy (odds ratio 1.19, 95% CI 1.02-1.39, p=0.02), and absence of spikes in post-operative EEG at one year (odds ratio 4.2; 95% CI 2.52-16.6; p<0.002). In FCD sub-group, shorter duration of epilepsy (11.1 versus 16.1 years, p=0.03), absence of secondary generalized seizures (p=0.05), absence of spikes in post-operative EEG on seventh day (p=0.009) and one year (p=0.002) were associated with favorable seizure outcome.

Conclusion: Majority of patients with MCD and refractory epilepsy when operated early remains seizure-free. Shorter duration of epilepsy is the single most important pre-operative variable and absence of spikes in post-operative EEG, predicts a long-term favorable seizure outcome.

Keywords: FCD; Malformations of cortical development; Outcome; Predictors; Surgery.