SLEEP-RELATED HYPERMOTOR (HYPERKINETIC) EPILEPSY (SHE)

• Familial focal epilepsy with variable foci (FFEVF): whereas seizures compatible with SHE can occur in an individual in a family with FFEVF, familial SHE is distinguished from FFEVF by all affected individuals in the family having seizures compatible with SHE.
• Parasomnias: seizures in SHE are typically brief (<2 min), with abrupt onset/offset, have stereotyped motor features from seizure to seizure, and can occur nightly with clustering through the night (from sleep onset to the early morning), and there is often preserved awareness during the seizure. Parasomnias are longer in duration (>10 min), have variable features from event to event, and are less frequent, often singular in a night, and prominent 1–2 h after falling asleep; the patient is confused during the event, with no memory of it afterward.
• <Non-epileptic seizures: patients with SHE may be misdiagnosed as having non-epileptic seizures, because they may have preserved awareness in the presence of bilateral movements during their seizures, and the ictal EEG may not show definitive ictal patterns. SHE may be differentiated from non-epileptic seizures by the stereotyped hyperkinetic features, brevity, and clustering of seizures through the night from sleep, whereas events in non-epileptic seizures are less stereotyped and occur during wakefulness.
• REM behavior disorder: This is a REM parasomnia that begins usually later in life (>50 years). Hyperkinetic movements are not stereotyped and correspond to vivid dreaming.
• Other focal seizures occurring predominantly from sleep: These do not have the characteristic hyperkinetic or asymmetric tonic/dystonic features seen in SHE.