Purpose of review: This article summarizes the clinical and electrophysiologic manifestations of nocturnal seizures, particularly nocturnal frontal lobe epilepsy (NFLE), parasomnias, and other disorders presenting with complex behaviors in sleep. The evaluation and treatment of patients with complex nocturnal behaviors can be challenging. While the differential diagnosis of sleep-related movements, including physiologic and pathologic phenomena, is extensive, the focus of evaluation in patients with complex nocturnal behaviors distinguishes between nocturnal seizures and parasomnias.
Recent findings: Seizures in NFLE have a wide range of complexity and severity, overlapping considerably with the disorders of arousal from non-REM (NREM) sleep. Video polysomnography with EEG (VPSG-EEG) has identified key clinical features useful in differentiating these disorders. A dysfunctional arousal mechanism involving the cholinergic system is involved in the pathophysiology of the autosomal dominant form of NFLE and NREM parasomnias. The high prevalence of parasomnias in NFLE families further confounds their distinction. VPSG-EEG combines PSG with comprehensive EEG to evaluate unexplained nocturnal behaviors when epileptic seizures are suspected. This procedure provides improved detection of interictal and ictal EEG abnormalities and time-synchronized correlation of clinical and neurophysiologic phenomena.
Summary: The diagnosis of complex nocturnal behaviors is among the most difficult to establish in sleep medicine clinics and laboratories. VPSG-EEG is indicated in the evaluation of patients with complex nocturnal behaviors when routine EEG is nondiagnostic. Ongoing research is necessary to fully elucidate the pathophysiology of these disorders, which share a host of clinical manifestations.