POC10 The dark night: a family diagnosis

A 43-year-old woman presented with increasing daytime tiredness following a history of nocturnal events persisting from early childhood. She was told that she would wake and walk clumsily; she has no memory of the episodes, which last up to 30 min. EEG and 24-h ambulatory EEG showed no abnormality but nor did they capture any episodes. Sleep was disrupted, with stage 3 NREM (slow wave, deep) sleep only reached once that night. Her striking four-generation family history of nocturnal events raised the possibility of autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) with epileptic nocturnal wandering. After many months, her husband managed to obtain video footage of an event. She walked, sometimes engaging in limited conversation or performed simple tasks such as switching on the television or opening the front door. This is truly a family disorder: not only is the parasomnia inherited in an apparently autosomal dominant manner, but it took the help of her husband—with the video—to be certain that this was NREM somnambulism. The allele HLA-DQB1*05 is overrepresented in somnambulism (35% of sleepwalkers and 13.3% controls), as well as REM sleep disorders and narcolepsy, but she was negative for this. In support of parasomnia however, she wakes in the first third of sleep, normally within an hour of going to bed. Although stereotyped, the events are too sophisticated and the duration is longer than expected for ADNFLE.