Occipital lobe developmental malformations and epilepsy: clinical spectrum, treatment, and outcome.

Abstract

Cortical developmental malformations (CDM) are increasingly recognized in association with epilepsy. We describe 10 patients (age range 14-35 years) with symptomatic occipital lobe epilepsy and CDM. Neurologic, neuroophthalmologic and electrophysiologic studies were performed. Patients had MRI, SPECT, and in some cases intracranial EEG investigators. Mean age of seizure onset was 8 years. We noted strong correlations between the presence of visual auras, the scalp EEG pattern, and the subtype of underlying pathology. Magnetic resonance imaging (MRI) showed CDM in all patients, with polymicrogyria and focal dysplasia being the most frequent malformations. Despite the presence of occipital lobe structural malformations in all patients, visual field deficits were present in only 2. Those who underwent cortical resections were seizure-free or showed major improvement at a mean follow-up of 3.5 years. Intracranial stimulation studies and the low frequency of pre- and postoperative deficits suggest that some degree of cortical visual reorganization may occur in patients with occipital lobe malformations. Occipital lobe CDM should be sought as a cause of symptomatic occipital lobe epilepsy even though they may become symptomatic after childhood.