Retained language in dysgenic cortex: case report.

Since the advent of magnetic resonance imaging, there has been renewed interest in disorders of cortical migration in the cause of focal epilepsy. The function of dysplastic cortex is poorly understood. We report a 46-year-old woman in whom this was assessed by intraoperative stimulation. This left-handed patient had a 30-year history of complex partial seizures with secondary generalization. Prolonged electroencephalographic recordings documented an epileptic focus in the right lateral and inferomesiotemporal lobe. Computed tomographic scanning and angiography suggested a right posterotemporal hamartoma. Amytal testing showed major speech representation in the right hemisphere. At craniotomy, an ivory-colored, posterotemporal lesion originating 5 cm from the temporal tip and 4 cm in diameter occupied the posterotemporal region. Electrical stimulation of this lesion produced speech interference. A histological examination of the resected anterotemporal lobe, amygdala, and hippocampus and biopsy specimens of the lesion showed extensive multifocal cortical microdysgenesis and gliovascular and cortical hamartoma. This case shows that grossly dysplastic cortex can remain functional. Cortical mapping under local anesthesia should be performed before resection of dysplastic lesions in putatively functional areas in patients with intractable epilepsy.