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What is Sleep-related hypermotor epilepsy and explain in detail?
Sleep-related hypermotor epilepsy (SHE), previously known as nocturnal frontal lobe epilepsy, is a form of focal epilepsy characterized by seizures which arise during sleep. The seizures are most typically characterized by complex motor behaviors. It is a relatively uncommon form of epilepsy that constitutes approximately 9-13% of cases. This disorder is associated with cognitive impairment in at least half of patients as well as excessive daytime sleepiness due to poor sleep quality. This disorder is sometimes misdiagnosed as a non-epileptic sleep disorder. There are many potential causes of SHE including genetic, acquired injuries and structural abnormalities.

History
In 1981, Lugaresi and Cirignotta described a group of 5 patients with paroxysmal attacks of violent movements of the extremities and dystonic-tonic posturing. It was initially uncertain whether these events constituted seizures or something else. However, the patients had a good clinical response to the anti-seizure medication carbamazepine. Ultimately, the epileptic nature of this condition was confirmed with EEG and suggested that they were coming from the frontal lobe. The term “nocturnal frontal lobe epilepsy” was suggested as a name for this condition. Later in 2014, a consensus conference recommended that the name be changed to sleep-related hypermotor epilepsy. There were three main justifications for this change: (1) not all seizures arise from the frontal lobe; (2) seizures do not necessarily occur during the night but rather from sleep; (3) hypermotor describes the most common visible clinical manifestation of the seizures.

Symptoms
Seizures in SHE are brief and usually have an abrupt onset and offset. The observable clinical manifestations may consist of rapid, hyperkinetic movements as well as tonic/dystonic posturing of the limbs. Other potential manifestations include brief arousals from sleep or wandering ambulatory behavior. Non-motor manifestations (such as sensory or emotional phenomenon) are common and retained awareness during seizures may occur. Seizures usually occur during non-REM sleep. The frequency of seizures can be very high and as many as dozens may occur every night which results in poor sleep quality. In addition, many patients with SHE suffer from cognitive impairment and have behavioral/psychological problems. There are many risks associated with nocturnal seizures including concussion, suffocation and sudden unexpected death (SUDEP).

Cause
Approximately 86% of SHE cases are sporadic, 14% of patients have a family history of epilepsy and 5% are inherited in an autosomal dominant manner (i.e. autosomal dominant sleep-related hypermotor epilepsy). Both genetic, structural and multifactorial etiologies can occur. In structural cases, the most common pathology is focal cortical dysplasia.The first described mutation in SHE was found in genes coding for the neuronal nicotinic acetylcholine receptor. Since then multiple other genes have been identified including KCNT1, DEPDC5, NPRL2, NPRL3, PRIMA1, CABP4, CRH and others. In some cases, structural and genetic etiologies can coexist such as with mutations in DEPDC5.

Diagnosis
The condition may be difficult to diagnose and misdiagnosis is common.  The subject may be unaware they have a seizure disorder. To others, the involuntary movements made during sleep may appear no different from those typical of normal sleep. People who have nocturnal seizures may notice unusual conditions upon awakening in the morning, such as a headache, having wet the bed, having bitten the tongue, a bone or joint injury, muscle strains or weakness, fatigue, or lightheadedness