Nocturnal frontal lobe epilepsy

The paroxysmal motor events during sleep are certainly common.The systematic use of nocturnal video-polysomnography has largely improved the diagnostic yield in patients with clusters of nocturnal motor events. Two broad nosological categories have been identified: parasomnias (sleep terror and sleep-walking), which are thought to represent disorders of arousal during sleep,and the epileptic seizures arising from sleep (nocturnal epilepsy). In recent years, particular attention has been devoted to those seizures arising from epileptic foci located within the frontal lobe or within the temporal lobe with early involvement of the frontal lobe: so-called nocturnal frontal lobe epilepsy (NFLE). Also in recent years the clinical, neuroradiological and neurophysiological profile of NFLE has clearly been delineated: up to 40% of patients with NFLE had at least one first-degree relative with a probable primary parasomnia;about 20% of patients had a family history of epilepsy; 5 to 10% had NFLE, with nocturnal seizures quite similar to those of the proband; the age at onset of seizures ranged from 1 to 65 years; the mean frequency of seizures was 15–20 per month; patients often complained of nocturnal sleep disruption (about one half of them reported excessive daytime sleepiness); one third of patients also had occasional seizures during wakefulness, usually in childhood; the seizures had a stereotypic motor pattern, of various complexity; traditional neuroradiological examinations showed abnormalities in about 10% of cases; there was a wide intra-familial variation in the severity of seizure disorder. There was also considerable intra-individual variation in severity during the different periods of life, with an age-dependent degree of severity; ictal EEG abnormalities were found in 30 to 60% of patients; the EEG during sleep showed interictal focal epileptiform abnormalities in about 50% of patients; in about two third of patients carbamazepine, clonazepam or their association were able to greatly reduce nocturnal seizures in frequency and complexity and, in some cases, to completely control them. The differential diagnosis between sporadic (and familial) NFLE from benign parasomnias is difficult from the history alone. A full video-polysomnographic study should be proposed to all the patients complaining of repeated nocturnal motor, autonomic and behavioural episodes, in order to provide a correct diagnosis.