Sleep-related hypermotor epilepsy in a patient with mucopolysaccharidosis type III

Both non-epileptic sleep disturbances and epilepsy are common in patients with mucopolysaccharidoses (MPS), so diagnosis of sleep-related hypermotor epilepsy in these patients is a tackling issue. We present a case of an adult patient with MPS IIIB (Sanfilippo syndrome), who presented with numerous nocturnal events of sudden awakening and hypermotor behavior, which had been previously regarded as parasomnias. Overnight video-EEG captured numerous stereotypical seizures with ictal pattern in the frontal regions, which led the diagnosis of SHE. The patient was started with carbamazepine, which resulted in a substantial reduction in the number of seizures. Our report provides further support for use of overnight video-EEG in the differential diagnosis of sleep-related disorders in MPS, yet true incidence of SHE in MPS patients remains unknown.