The age of oneset of narcolepsy ranges from early childhood to the fifth decade (with a peak at 15 years and 35 years of age). Cataplexy is the optimal behavioural biomarker of this disease. In addition to cataplexy, narcolepsy is characterized by sleep paralysis, sleep-onset REM periods, hypnagogic hallucinations and fragmented night-time sleep. The evolution of the disease is often stable with a frequent improvement of sleepiness and cataplexy, but with age there is an aggravation of the poor quality of night sleep.Cataplexy is defined as a sudden involuntary muscle weakness or paralysis during wakefulness, typically triggered by strong emotions, and is the pathognomonic symptom of narcolepsy with cataplexy ( a sleep disorder that affects 0,06% of the adult population).
#Symptoms of cataplexy professional#
Narcolepsy can severely disable scholarly and professional performances. A good sleep hygiene is always recommended, with scheduled short naps, and regular sleep habits. Sodium oxybate is efficient for sleepiness, cataplexy and disturbed nocturnal sleep. Second-line treatments are methylphenidate, solriamfetol or amphetamines. First-line treatment of diurnal sleepiness is often with modafinil but it can be also with pitolisant or sodium oxybate. It comprises stimulants (modafinil, methylphenidate, amphetamine, pitolisant, solriamfetol), anticataplectic drugs (antidepressants) or sodium oxybate. Treatment is nowadays only symptomatic, as the loss of orexin neurons is irreversible. Rare familial cases have been reported (<2%) however the mode of inheritance is unclear. In absence of typical cataplexy, other causes of sleepiness must be considered, such as chronic insufficient sleep, idiopathic hypersomnia or narcolepsy without cataplexy, now called narcolepsy type 2. Differential diagnosisĬataplexy must be typical to be confident with the diagnosis. The presence of low hypocretin-1 levels (<110 pg/ml) in the cerebrospinal fluid can confirm the diagnosis with an excellent sensibility and specificity. Nocturnal and daytime polysomnography demonstrate an average sleep latency of under eight minutes with at least two sleep onset rapid eye movement periods (SOREMP) on multiple sleep latency tests. Diagnostic methodsĭefinitive diagnosis requires the presence of clinical symptoms, characteristic polysomnography findings and/or low hypocretin-1 levels in cerebral spinal fluid. An autoimmune origin for the disease is highly suspected, particularly environmental factors interacting with susceptibility genes (more than 98% of the patients carry the HLA-DQB1*0602 allele) however, this is unproven. The disease is due to loss or impairment of the orexin/hypocretin neurons of the lateral hypothalamus that results in decreased hypocretin-1 levels in the cerebrospinal fluid. Other, non specific, clinical signs include hypnagogic hallucinations, sleep paralysis, disturbed nocturnal sleep, and weight gain, especially in children.
The average time between the age of appearance of the symptoms and the diagnosis is still very long, 10 years. The age of onset varies between 10 and 30 years old and symptoms are lifelong. Narcolepsy type 1 prevalence is estimated between 1/2,000 and 1/5,000.
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