During these events, patients continue the activity they initiated half asleep and have no recollection, for example continuing to write gibberish on a piece of paper. Other times, patients would fight though sleep attacks and this can lead to “automatic behaviors”. If the patient can, he/she would take a nap and very often would feel better even after 15-30 min of sleep. On top of this background of constant sleepiness, sudden sleep attacks can appear that are so strong that the patient cannot stay awake and struggles. In general, patients feel exhausted all the time and would fall asleep as soon as they are not moving or being stimulated (for example as a passenger in a car). Sleepiness is the most problematic symptom in narcolepsy. Only after many months the cataplexy starts then to transform into the “adult” form only triggered by jokes or laughing. Children can also feel generally weak, having trouble walking. Although cataplexy is most often triggered by emotions such as a good joke or a funny cartoon, in children close to onset, it can be atypical and manifest by mouth opening, jaw dropping with tongue protrusions that are not always obviously triggered by emotions. Reflexes are abolished during the attack. In severe cases, the patient might fall and become completely paralyzed for a few seconds to several minutes. In other typical cataplectic attacks, the head may drop or the jaw may become slack. Typically, the patient's knees buckle and may give way upon laughing, elation, surprise, or anger. Cataplexies are sudden, brief episodes of muscle weakness triggered by emotions. Indeed, patients with narcolepsy enter REM sleep abnormally fast, minutes after falling asleep unlike normal people where REM sleep only appear after one hour of sleep (see History of Narcolepsy).Ĭataplexy is unique to NT1. Since the 1960s it has been known that several of the disabling symptoms of narcolepsy, such as sleep paralysis, cataplexy and hypnagogic hallucinations, are pathological equivalents of REM sleep (a stage of sleep when we dream but are paralyzed to avoid moving in our dreams). A rapid gain of weight often also occurs. About half of all patients start narcolepsy before age 18, in rare cases as young as 3 years old, and in general the younger it starts, the more severe and abruptly the disease strikes in young children one often observed a regression where tantrums and bad behavior restarts because the child is always exhausted. It affects about 0.03% of the population (1 for 3,000 individuals) in most countries in the world. However, there is efficacious treatment.The main symptoms of narcolepsy type 1 (NT1) are excessive daytime sleepiness, cataplexy, sleep paralysis, hypnagogic hallucinations, and disturbed nocturnal sleep. However, this HLA type is also found in 15-25% of healthy people. The diagnosis is made in a sleep laboratory with polysomnography and a multiple sleep latency test (MSLT) and after exclusion of other causes of EDS.Īnother biologic marker is the presence of the HLA DQB1*06:02 type, found in the 90-95% of NT1 and in a large proportion of people with NT2. In type 2, there is no cataplexy and no proven hypocretin deficiency. In type 1 there is clear-cut cataplexy (see below) or a proven undetectable amount of hypocretin-1 in the cerebrospinal fluid. Both types require the presence of 3 months of EDS. The diagnosis is established according to the International Classification of Sleep Disorders revised recently (ICSD-3, 2014), which classifies the disease in two subtypes: Narcolepsy type 1 (NT1) and type 2 (NT2). Progression of symptoms is unusual after 4-6 years. During the first years after the onset of the first symptoms, there may be progression in severity of the existing symptoms and additional symptoms may develop. The onset can be at any age, but there is a clear bimodal distribution with peaks at age 15 and 36 years. The majority of narcolepsy cases are idiopathic (that is of unknown cause) and non sporadic (no family history), about 1-5% are familial or secondary tp a brain disorder. Recent observations, suggest that narcolepsy may represent an autoimmune disorder, which arises from a combination of genetic predisposition and such environmental factors as infections and vaccinations eventually leading to a selective loss of hypocretin neurons in the hypothalamus, a structure in the middle of our brain. It is rare, affecting 20-40 out of 100,000 persons, and presents with excessive daytime sleepiness (EDS), cataplexy (loss of muscle control triggered by emotions), disturbed sleep, hypnagogic hallucinations and sleep paralysis. Narcolepsy is a chronic, neurological disease.
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