The neurophysiological evaluation of nocturnal frontal lobe epilepsy.

The most reliable technique for the diagnosis of nocturnal frontal lobe epilepsy (NFLE) is nocturnal video-polysomnography, which is an expensive procedure and unavailable in many Departments of Neurology and Epileptology around the world. The aim of the present study was to evaluate the role of routine video-EEG and video-EEG after sleep deprivation, during the daytime, in the diagnosis of NFLE. We studied 23 patients complaining of repeated nocturnal motor attacks using a 3-level neurophysiological evaluation, including video-EEG when awake (level 1), video-EEG after sleep deprivation, during the daytime (level 2) and nocturnal video-polysomnography (level 3). All the patients had a normal video-EEG when awake. The video-EEG after sleep deprivation (level 2) allowed a diagnosis of NFLE in 52.2% of the patients, while the nocturnal video-polysomnography (level 3) allowed this diagnosis in 87.0% of the same sample. In the patients complaining of repeated nocturnal motor attacks, a video-EEG after sleep deprivation performed during the daytime, could be useful for diagnosis in about one half of cases. This methodology is routinely performed in many Departments of Neurology and Epileptology, and is much less binding and expensive than nocturnal video-polysomnography and so it could be important economically for the health service.