Seizure outcome after surgery for focal epilepsy due to malformation of cortical development (MCD), identified by MRI, was evaluated in 35 patients aged 3 months to 47 years (median, 14 years) operated at the Cleveland Clinic Foundation. Outcome classified according to Engel was Class I with no seizures or only auras in 17 (49%), Class II with rare disabling seizures in 8 (23%) patients, some improvement in 20%, and no change in 9%. A seizure-free outcome was more common among patients with complete cf incomplete resection of unilateral MCD (difference NS). MRI evidence of hemimegalencephaly or bilateral MCD was indicative of a poor outcome. 
COMMENT. A seizure-free outcome may follow surgical resection in approximately one half of patients with intractable focal epilepsy due to cortical malformation. Complete resection of a unilateral, MRI-defined lesion carries the best prognosis.