Epilepsy in cortical dysplasia: factors affecting surgical outcome

To determine the factors influencing the outcome of cortical dysplasia resection for medically refractory epilepsy.

13 patients underwent craniotomy for resection of epileptogenic foci using electrographic and MRI guidance. All patients had had seizures for more than 2 years and were on 3 or more antiepileptic medications. Their preoperative evaluation included MRI, neuropsychological evaluation including the WADA test, video EEG monitoring and intraoperative electrocorticography. Invasive preoperative monitoring was employed in 8 cases. The Engel outcome classification system was used. The mean follow-up time was 60.1 months with a minimum follow-up of 24 months.

Postoperatively, all 6 patients younger than 18 years were seizure free. Among 7 patients older than 18 years, 6 were class II and 1 was class III. Based on their preoperative MRI studies, among the patients with abnormal studies, 2 were class I, 5 were class II and 1 was class III. Among patients with normal studies, 4 were class I and 1 class II. Regarding the ictal EEG findings, among patients with localizing findings, 4 were class I and 5 were class II. Among patients with no localization in their ictal EEG, 2 were class I, 1 class II and 1 class III. Regarding the invasive preoperative monitoring of the 7 patients with localizing findings, 5 were class I and 2 were class II. The only patient with nonlocalizing findings was class II. Finally, among the patients with no invasive preoperative monitoring, 3 were class I, 1 was class II and 1 was class III.

Cortical resection is an effective treatment modality in patients with medically refractory epilepsy. In our series, the outcome was better in patients less than 18 years old and patients with normal preoperative MRI studies.