Cataplexy

Abstract

Remarkably and almost invariably, the clinical phenomenon of cataplexy results from the loss of around 40 000 hypocretin-containing neurones in the lateral hypothalamus in the context of narcolepsy type 1. Cataplexy reflects the dysregulation of rapid-eye-movement (REM) sleep, such that REM-sleep atonia intrudes inappropriately into wakefulness as brief episodes of either focal or total paralysis of voluntary muscle. The semiology of cataplexy differs between adults and children. A defining and enigmatic aspect is that certain emotional stimuli usually trigger the episodes. Cataplexy can be the most disabling symptom of the narcolepsy syndrome, severely limiting normal activities of daily living. Antidepressant drug therapy at relatively low doses is the traditional treatment; these most likely work through inhibiting REM sleep, predominantly by increasing brain monoamine concentrations. Sodium oxybate is probably the most effective drug for severe cataplexy, taken before overnight sleep and once through the night; its precise mechanism of action remains obscure. Pitolisant is a new agent for treating the excessive daytime sleepiness of narcolepsy that also helps cataplexy control by increasing histamine concentrations in the hypothalamus. Further understanding of the neurobiology of cataplexy and how it relates to hypocretin deficiency should improve our understanding of the brain’s emotional processing and provide insights into REM sleep and its control.

Central Neurocytoma Presenting as Symptomatic Cataplexy

“…4 Patient with cataplexy has been known to have abnormal activity in reward brain circuit. 5 Alterations of striatal dopaminergic system in narcolepsy with cataplexy also have been reported. In functional brain study, patients with narcolepsy showed increased striatal D2 receptor binding and a positive correlation between this and the frequency of cataplexy and sleep attack.…”

Hypothalamic MCH Neuron Activity Dynamics during Cataplexy of Narcolepsy

“…Cataplexy, presented as a sudden skeletal muscle paralysis or weakness during waking, is the most disabling symptom of sleep disorder narcolepsy (Reading, 2019). In murine models of narcolepsy, cataplexy usually occurs during the active waking status of the animal, such as running, exploring, grooming, or responding to emotion stimuli (Morawska et al, 2011;Overeem et al, 2001;Reading, 2019). The brain circuitry responsible for cataplexy is not completely clear.…”

Gelastic Cataplexy in Niemann Pick Type C

“…It is commonly a component of the narcoleptic syndrome alongside daytime sleepiness, sleep paralysis, and vivid hallucinations at the beginning and end of sleep. 4 Cataplexy is thought to represent brief episodes of REM sleep paralysis during wakefulness and probably involves the same neural networks that generate normal muscle atonia in REM sleep. Treatment of cataplexy by tricyclic antidepressants is often successful.…”