Nocturnal epileptic seizures versus the arousal parasomnias

Abstract

We review here the clinical features of Nocturnal Frontal Lobe Epilepsy (NFLE) and the arousal parasomnias, to define possible differential diagnostic criteria and their inter-observer reliability, and to determine whether both conditions share a common disturbance of arousal mechanisms. Polysomnographic recordings defined several types of seizures in NFLE: Paroxysmal Arousals (PA), Nocturnal Paroxysmal Dystonia (NPD), Epileptic Nocturnal Wanderings (ENW). There are however several difficulties with the diagnosis of NFLE, not the least being that EEG discharges during the seizures are not universally found. These diagnostic difficulties are highlighted, as well as the fact that studies of the inter-observer reliability of the video polysomnographic features of NFLE were found unsatisfactory, especially for the PA. When NFLE patients and their relatives were matched to control subjects and analysed in regard to personal and family history for the parasomnias, the arousal parasomnias were reported significantly higher by patients with NFLE and their relatives. This higher recurrence of a personal and family history for the parasomnias in NFLE patients suggests that the two conditions share a common underlying mechanism. Based on evidence from Autosomal Dominant NFLE, a genetic disorder with mutations in nicotinic acetylcholine receptors(nAchR), we hypothesise that arousal parasomnias and NFLE both, have abnormal arousal mechanisms in the dorsal cholinergic arousal branch triggering peculiar motor patterns in the medial frontal lobe regions.