Abstracts

Rationale: Paroxysmal nocturnal dystonia (PND) has been established as a form of nocturnal frontal lobe epilepsy (NFLE). Insight into the genetics of paroxysmal nocturnal events has made it possible to sort out certain types of these events as inherited forms of NFLE. Still, the majority of cases of NFLE are not linked to a known genetic mutation suggesting significant genetic and phenotypic heterogeneity, hence the need for further studies to discern the nature of different types of episodic nocturnal events.Methods: We report a Korean family (a mother and daughter) who presented with frequent stereotyped paroxysmal nocturnal motor events without any typical tonic or clonic seizures. Video-EEG monitoring/polysomnogram, neuropsychological evaluation, and genetic testing were obtained. Results: The nocturnal episodes consisted of arousal from NREM sleep followed by motor activity including bilateral hand posturing that was not associated with any discernible epileptiform discharges on the EEG. Neuropsychological evaluation revealed normal IQ but moderate and severe memory deficits in the mother and daughter, respectively. Genetic testing revealed the CHRNB2 mutation I312M located in transmembrane region 3 (M3), near the known cluster of ADNFLE mutations, that has been reported in two European twins with NFLE and memory deficits. The clinical episodes were completely controlled in both patients following treatment with carbamazepine.Conclusions: The full spectrum of electroencephalographic, clinical and genetic features associated with NFLE is to be defined. Presence of the same phenotype in patients carrying the CHRNB2 mutation I312M in unrelated European and Korean families suggests the determining role of this particular mutation in the development of memory deficits.