Surgical pathologic findings of extratemporal-based intractable epilepsy: a study of 133 consecutive resections

Surgical management of intractable epilepsy continues to be important in select cases to achieve seizure control.

This study retrospectively reviews the pathologic findings in 133 consecutive cases of extratemporal lobe epilepsy experienced during a 17-year period.

The study group consists of 133 patients (78 males) who underwent extratemporal lobe resection for epilepsy at a mean age of 21.1 years (range, 3 months to 57 years). In 50 patients (37.6%), cortical dysplasia (neuronal migration abnormalities) was identified. The most common patterns of dysplasia observed included diffuse architectural disorganization in 46 cases, neuronal cytomegaly in 30 cases, increased numbers of molecular layer neurons in 30 cases, and balloon cells in 18 cases. Tumors were identified in 37 cases (27.8%) and included 13 astrocytomas, 7 gangliogliomas, 6 dysembryoplastic neuroepithelial tumors, 6 glioneuronal hamartomas, 4 oligodendrogliomas, and 1 oligoastrocytoma (mixed glioma). Twenty-four resections (18%) showed evidence of remote ischemic damage or infarct. Neuronal heterotopia was identified in 59 resection specimens (44.4%). Other less common findings included vascular malformations in 4 patients (3.0%), Sturge-Weber malformations in 3 patients (2.3%), and Rasmussen encephalitis in 2 patients (1.5%). Two patients were known to have tuberous sclerosis. In 23 resection specimens (17.3%), no significant pathologic finding was identified. Coexistent cortical dysplasia and tumor were seen in 10 cases and coexistent dysplasia and infarct or remote ischemic damage in 11 cases.

This series demonstrates that most patients with extratemporal lobe epilepsy have significant histopathologic findings, which most frequently include cortical dysplasia, tumor, or evidence of remote ischemic damage or infarct. Coexistent pathologic findings were present in a significant minority of cases (16.5%).