P89. Differential diagnosis between epilepsy and parasomnia may be difficult even on 10–20 video-EEG

Abstract

Sleep related attacks of bizarre complex movements may be due to either epilepsy or non-REM parasomnia. Differential diagnosis can be especially difficult in mentally retarded patients due to lack of detailed medical history and presence of epilepsy risk factors such as brain lesions. We present the case of a 19 year-old male with history of preterm birth, perinatal intracerebral hemorrhage, and post-hemorrhagic hydrocephalus. His parents reported up to 20 attacks per night characterized by startle from sleep, fearful expression in his eyes, grabbing hold of the bedframe, body rocking, and groaning, each episode lasting between 10 and 30 s. Several standard EEGs were normal. Cranial computed tomography (CT) scan showed a ventriculo-peritoneal shunt catheter in place. He was diagnosed with parasomnia following standard polysomnography in an external sleep laboratory. In our institution, polysomnography and 10–20 video EEG monitoring were performed for four nights, and 13 of the habitual attacks were recorded. All attacks occurred out of sleep with six attacks occurring from slow-wave sleep (N3) and seven occurring out of light sleep (N2). All but one attack were lacking an ictal EEG change, only one event was associated with rhythmic evolving theta in the left frontal region lasting for a few seconds. Tachykardia of up to 170 beats per minute was seen in all events. Video review revealed that the sequence of clinical features was extremely stereotypical and monomorphic across all 13 events. Interictal EEG was completely normal during the awake stage as well as during sleep in the first and second nights. Only in nights three and four, interictal sleep EEG revealed several spikes in the left frontal region. We diagnosed left frontal lobe epilepsy with exclusively sleep-related hypermotor seizures and stared the patient on anticonvulsant medication. This case demonstrates that the differential diagnosis of epilepsy versus Non-REM parasomnia may be difficult even with 10–20 video EEG. The vast majority of seizures (or all) may lack an ictal EEG pattern, and interictal epileptiform spikes or sharp waves may be very infrequent or absent. Short events with a very stereotypic sequence of clinical features as well as attacks arising from light sleep (N2) support the diagnosis of epilepsy. One or two nights of polysomnography – even with an extended 10–20 EEG montage – may not be sufficient to differentiate parasomnia from epileptic seizures.