Characterizing Onset Limit and Surgical Outcome Factors in Type II Focal Cortical Dysplasia-Related Epilepsy

To clarify the upper limit of epilepsy onset in focal cortical dysplasia (FCD) Type II (FCD)-related epilepsy and to investigate factors affecting long-term surgical outcomes from an open-source database.

Patients with FCD Type II pathology were included from the Imaging Database for Epilepsy And Surgery. The primary outcome measure was the incidence of adult-onset FCD-drug resistant epilepsy (DRE). Secondary analyses focused on factors affecting long-term seizure-free outcomes after resective epilepsy surgery for FCD-DRE.

Thirty-nine FCD-DRE patients were identified. Pathology was Type IIB (n = 30), Type IIA (n = 8), and Type II Not Otherwise Specified (n = 1). Only 5% had adult-onset DRE; 95% had onset before 15 years. Surgery was associated with 71.4% 5-year International League Against Epilepsy Class I outcome. FCD Type IIB was associated with high rate of seizure-free outcome (OR 13.0, 95% CI [1.36-124], p = 0.03). Focal-to-bilateral-tonic-clonic seizures, focal impaired consciousness seizures, prior status epilepticus, sex, hemisphere, age of epilepsy onset, and age of surgery were not associated with 5-year seizure-free outcome.

Prior data show that ∼5% of FCDs are discovered incidentally. This study elucidates that the majority of FCD-DRE (including those patients treated as adults) is childhood-onset. These data demonstrate that FCD Type II (especially Type IIB) is associated with high rates of durable postsurgical seizure-free outcome.