Seizures with paroxysmal arousals in sleep-related hypermotor epilepsy (SHE): Dissecting epilepsy from NREM parasomnias

Objective Sleep-related hypermotor epilepsy (SHE) is a focal epilepsy characterized by seizures occurring mostly during sleep, ranging from brief seizures with paroxysmal arousals (SPAs) to hyperkinetic seizures and ambulatory behaviors. SPAs are brief and stereotypic seizures representing the beginning of a major seizure. Distinguishing SPAs from disorders of arousal (DOAs) and their briefest episodes called simple arousal movements (SAMs) is difficult. We performed a characterization of SPAs and SAMs to identify video-polysomnographic (VPSG) features that can contribute to the diagnosis of SHE or DOA. Methods Fifteen SHE, 30 DOA adult patients, and 15 healthy subjects underwent full-night VPSG. Two neurologist experts in sleep disorders and epilepsy classified all the sleep-related movements and episodes recorded. For each SPAs and SAMs, sleep stage at onset, duration, limb involvement, progression, and semiology have been identified. Results A total of 121 SPAs were recorded, emerging mostly during stage 1-2 non-rapid eye movement (NREM) sleep (median duration: 5 seconds). At the beginning, the SPAs motor pattern was hyperkinetic in 78 cases (64%), involving more than three non-contiguous or all body parts. The standard was a constant progression of movements during SPAs without any motor arrests. In DOA patients a total of 140 SAMs were recorded (median duration: 12 seconds) mostly emerging during stage 3 NREM sleep. In SAMs, we did not observe any tonic/dystonic or hypermotor patterns or stereotypy; motor arrest was present over the course of about half of the episodes. In comparison with both DOA and healthy subjects, SHE patients showed a higher number of sleep-related movements per night and a reduction of sleep efficiency. Significance SPAs and SAMs present different semiological and clinical features. Their recognition could be useful to drive the diagnosis when major episodes are not recorded during VPSG in patients with a clear clinical history of SHE or DOA.