Abstracts

RATIONALE: Band heterotopia or "double cortex" is a rare and highly abnormal neuronal migration disorder in which seizures are a common manifestation. We report the clinical and electrographic features of multiple seizure types in a young girl with this structural brain disorder. METHODS: Continuous video-EEG monitoring was performed on a 9-year-old girl with band heterotopia, mental retardation, and medically refractory epilepsy to document the clinical and electrographic features of her seizures. RESULTS: The patient had three distinct clinical seizure patterns. The most frequent clinical seizure, occurring thousands of times per day, consisted of a momentary cessation of ongoing activity, rarely accompanied by brief eyelid flutter. Although muscle tone was often lost, these seizures were easily overlooked due to their brevity. Electrographically each seizure was clearly associated with a generalized spike or polyspike and slow wave discharge. Atonic (head drop) seizures were associated electrographically with a generalized high-amplitude sharp and slow wave discharge followed by generalized paroxysmal fast activity (GPFA). Atonic seizure progressing into a generalized tonic-clonic seizure with asymmetric features was correlated with GPFA followed by disorganized, generalized spike and slow wave, in turn followed by an asymmetric, generalized, ictal pattern of rhythmic, sharply contoured alpha and theta. Interictally the EEG demonstrated multi-focal independent epileptiform discharges and generalized slowing. CONCLUSIONS: Clinical seizures and associated electrographic ictal features of a patient with band heterotopia were characteristic of a symptomatic generalized epilepsy. The scalp EEG of such a patient likely reflects electrical activity only in the outer cortex, which in this patient was capable of generating a spectrum of ictal and interictal EEG patterns indistinguishable from those seen in the "single" cortex of other patients with secondary generalized epilepsies.