[Autosomal dominant nocturnal frontal lobe epilepsy: the syndrome]

The identification of the autosomal dominant nocturnal frontal lobe epilepsy (ADNFLE) in 1994 was rapidly followed by that of other familial forms of non lesional partial epilepsies (familial temporal lobe epilepsy, autosomal dominant partial epilepsy with variable foci). Since then around forty families with ADNFLE have been described, most of them having only 3 or 4 affected individuals. The epilepsy usually begins during childhood (mean age at onset: 11 years). The seizures mainly consist of motor elements which can be dystonic, tonic or hyperkinetic (bipedal automatisms, pelvic thrashing movements...), often preceded by a non specific aura. They are brief and frequent, taking place at night, in clusters. Some patients also present some diurnal seizures. One third of the patients report the occurrence of rare secondarily generalized tonic-clonic seizures. There is a large intra-familial variability as to age of onset, intensity of the manifestations and the course of the epilepsy. During the period of highest frequency of seizures, some patients may present moderate neuropsychological disturbances concordant with frontal dysfunctioning, or transitory behavioral disorders. The seizures often subside with age and may even disappear at adulthood. The most effective antiepileptic drug is carbamazepine, however pharmacoresistance is seen in 20 to 30 p. 100 of the cases. Interictal EEG shows non specific epileptiform anomalies with a frontal predominance, often seen solely on sleep recording, in more than half of all patients. Ictal EEG does not always give evidence of definite ictal discharges. The clinical heterogeneity of ADNFLE as it is especially observed in very variable types of auras which are non localizing, aside form the EEG's own limits, makes it difficult to localize the primary epileptic focus with certainty in the frontal lobe in all cases. In all, the clinical and electrical spectrum of ADNFLE is large, and the topographical identification of these familial frontal lobe epilepsies sets the same problems as for sporadic, classical cryptogenic frontal lobe epilepsies.