Cortical dysplasia in extratemporal lobe intractable epilepsy: a study of 52 cases

Cortical dysplasias or malformations due to abnormalities of cortical development are a well-recognized cause of intractable seizures. This study retrospectively examines the clinicopathologic features of 52 cases of extratemporal cortical dysplasia (from 135 total resections performed over a 16-year period). The study consists of 52 patients (27 males; 25 females) who underwent extratemporal resection for epilepsy at a mean age of 15.1 years (range, 3 months to 44.1 years). Seizure duration before surgery ranged from 7 to 372 months (mean duration, 129 months). Patterns of cortical dysplasia observed included diffuse architectural disorganization (n=48), neuronal cytomegaly (n=32), increased number of molecular layer neurons (n=32), balloon cells (n=19), gray matter heterotopia (n=3), neuronal glial clustering (n=3), and pial glial neuronal tissue (n=2). Five patients had coexistent nodular hamartomas. Coexistent tumors were present in five patients; including three dysembryoplastic neuroepithelial tumors, one ganglioglioma, and one low-grade fibrillary astrocytoma. Two patients had tuberous sclerosis. Follow-up was available in 50 patients (mean follow-up, 29 months). Thirty-eight patients (73%) had complete resolution or significant decrease in seizure frequency, 13 patients (25%) had increased seizures or no change in seizures, and one patient died in the postoperative period. In conclusion, (1). cortical dysplasia was identified in 38.5% of extratemporal resections for epilepsy; (2). the common cortical dysplasia patterns observed included diffuse cortical disorganization, neuronal cytomegaly, and increased molecular layer neurons; (3). 10% of extratemporal cortical dysplasia was associated with tumors; (4). improved seizure control was obtained in approximately three fourths of patients after resection; and (5). seizures associated with balloon cell dysplasia were less successfully managed with surgery.