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Cataplexy episode1/12/2023 ![]() ![]() Orexin neurons are wake-active, promoting arousal and maintaining wakefulness ( Adamantidis et al., 2007 Alexandre et al., 2013) while MCH neurons are predominantly rapid eye movement (REM) sleep-active and promote REM sleep ( Jego et al., 2013 Konadhode et al., 2013 Blanco-Centurion et al., 2016, 2019 Izawa et al., 2019). Orexin (hypocretin, HCRT) and melanin-concentrating hormone (MCH) are hypothalamic neuropeptides regulating sleep and wakefulness. Our results demonstrated the inactivation status of MCH neurons during cataplexy and suggested that MCH neurons are not involved in the initiation and maintenance of cataplexy in orexin knock-out mice. Importantly, a pre-cataplexy elevation of Ca 2+ signals from MCH neurons was not a prerequisite for cataplexy initiation. Moreover, MCH neurons displayed significantly lower Ca 2+ signals during cataplexy. Similar to wild-type mice, MCH neurons of the narcoleptic mice displayed significantly higher Ca 2+ transient fluorescent intensity during rapid eye movement (REM) sleep and active waking (AW) episodes compared with non-REM (NREM) sleep. Here we used the live animal deep-brain calcium (Ca 2+) imaging tool to record MCH neuron dynamics during cataplexy by expressing calcium sensor GCaMP6s into genetically defined MCH neurons in orexin knock-out mice, which are a model of human narcolepsy. As another integral group of sleep/wake-regulating neurons in the same brain area, the melanin-concentrating hormone (MCH) neurons’ involvement in cataplexy remains ambiguous. Importantly, management also needs to involve sleep hygiene advice, safety measures whenever applicable and guidance with regard to the social sequelae of cataplexy.Ĭataplexy Drop attacks Narcolepsy Pseudocataplexy Sodium oxybate Syncope.Hypothalamic orexin (hypocretin, HCRT) deficiency causes sleep disorder narcolepsy with cataplexy in humans and murine. ![]() Symptomatic treatment is possible with antidepressants and sodium oxybate. Over time, these severe symptoms evolve to the milder adult phenotype, and this pattern is crucial to recognize when assessing the outcome of uncontrolled case series with potential treatments such as immunomodulation. Cataplexy shows remarkable differences in childhood compared to adults, with profound facial hypotonia and complex active motor phenomena. Currently, the diagnosis of cataplexy is made almost solely on clinical grounds, based on history taking and (home) videos. Childhood narcolepsy, with its profound facial hypotonia, can be confused with neuromuscular disorders, and the active motor phenomenona resemble those found in childhood movement disorders such as Sydenham's chorea. They can be differentiated from cataplexy using thorough history taking, supplemented with (home)video recordings whenever possible. Cataplexy mimics include syncope, epilepsy, hyperekplexia, drop attacks and pseudocataplexy. Next to narcolepsy, cataplexy can sometimes be caused by other diseases, such as Niemann-Pick type C, Prader Willi Syndrome, or lesions in the hypothalamic or pontomedullary region. Moreover, childhood cataplexy differs from the presentation in adults, with a prominent facial involvement, already evident without clear emotional triggers ('cataplectic facies') and 'active' motor phenomena especially of the tongue and perioral muscles. The expression of cataplexy varies widely, from partial episodes affecting only the neck muscles to generalized attacks leading to falls. ![]() Although cataplexy is rare, its recognition is important as in most cases, it leads to a diagnosis of narcolepsy, a disorder that still takes a median of 9 years to be diagnosed. This review describes the diagnosis and management of cataplexy: attacks of bilateral loss of muscle tone, triggered by emotions and with preserved consciousness. ![]()
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