Nocturnal frontal lobe epilepsy: A clinical and polygraphic overview of 100 consecutive cases

Abstract

Nocturnal frontal lobe epilepsy (NFLE) has been delineated as a distinct syndrome in the heterogeneous group of paroxysmal sleep-related disturbances. The variable duration and intensity of the seizures distinguish three non-rapid eye movement-related subtypes: paroxysmal arousals, characterized by brief and sudden recurrent motor paroxysmal behaviour; nocturnal paroxysmal dystonia, motor attacks with complex dystonic-dyskinetic features; and episodic nocturnal wanderings, stereotyped, agitated somnambulism. We review the clinical and polysomnographic data related to 100 consecutive cases of NFLE in order to define the clinical and neurophysiological characteristics of the different seizure types that constitute NFLE. NFLE seizures predominate in males (7:3). Age at onset of the nocturnal seizures varies, but centres during infancy and adolescence. A familial recurrence of the epileptic attacks is found in 25% of the cases, while 39% of the patients present a family history of nocturnal paroxysmal episodes that fit the diagnostic criteria for parasomnias. A minority of cases (13%) have personal antecedents (such as birth anoxia, febrile convulsions) or brain CT or MRI abnormalities (14%). In many patients, ictal (44%) and interictal (51%) EEGs are uninformative. Marked autonomic activation is a common finding during the seizures. NFLE does not show a tendency to spontaneous remission. Carbamazepine completely abolishes the seizures in approximately 20% of the cases and gives remarkable relief (reduction of the seizures by at least 50%) in another 48%. VideoEEG recordings confirm that NFLE comprises a spectrum of distinct phenomena, different in intensity but representing a continuum of the same epileptic condition. We believe that the detailed clinical and videoEEG characterization of patients with NFLE represents the first step towards a better understanding of the pathogenic mechanisms and different clinical outcomes of the various seizure types that constitute the syndrome.