The epileptogenic area of cerebral cortex is localized by:

B. Observing the patient's seizures.

C. Electroencephalography

D. Visualizing cortical abnormalities on cerebral imaging studies. 

DISCUSSION: Since the exact anatomy of an epileptogenic focus remains obscure, the focus of the patient's seizures is determined by concordance of the clinical manifestations of the seizures, abnormalities demonstrated by cerebral imaging, and abnormalities demonstrated by electroencephalography.