While the cause of cataplexy is still being investigated, most people with cataplexy show a loss of certain brain cells that produce the hormone orexin (also called hypocretin). While type 1 and type 2 narcolepsy both have the name “narcolepsy” in it, the cause for type 1 narcolepsy is well understood (loss of a neurotransmitter, orexin), whereas the cause for type 2 narcolepsy is not well understood. For people with type 1 narcolepsy, episodes of cataplexy typically begin after the onset of excessive sleepiness. People diagnosed with type 1 narcolepsy experience episodes of cataplexy, while people with type 2 narcolepsy do not. There are two major types of narcolepsy: type 1 and type 2, differentiated by whether or not a person experiences cataplexy. Narcolepsy is a sleep disorder characterized by excessive daytime sleepiness, sleep paralysis, hallucinations, and, in some cases, cataplexy. Episodes typically last a couple of minutes and resolve on their own. Unlike other conditions that cause a loss of muscle control, like fainting or seizures, people experiencing cataplexy remain conscious and aware. During more severe episodes, a person collapses and cannot move or speak. Less severe episodes involve momentary sensations of weakness in a few muscles, while more severe episodes involve a total loss of voluntary muscle control. Episodes may also be triggered by anger, but rarely by stress, fear, or physical exertion.Įpisodes of cataplexy can vary in severity. The triggering experiences are usually positive, like laughter, witty conversations, and pleasant surprise. We will continue to monitor and revise this article as new literature is published on cataplexy.Ĭataplexy is a sudden muscle weakness that occurs while a person is awake. The exact pathophysiology of how this occurs is not clear for each of these conditions, although there are several suggestions and it is generally thought to be associated with cellular damage.Our medical review team has recently evaluated this page to ensure accuracy. These conditions are likely to contribute to the cause due to their impact on the neurons that are involved in the production of hypocretin. Other associated health conditions include:
The lesions typically present in the lateral and posterior hypothalamus but can also affect other areas of the brain, such as the stem, and can usually be detected with imaging techniques, such as magnetic resonance imaging (MRI) or computed tomography (CT) scans. This may be an astrocytoma, glioblastoma, glioma, subependymoma or other types of tumor. The most common condition is a tumor or lesion in the brain that obstructs the cells that produce hypocretin and affects the level of the neurotransmitter in the central nervous system. Secondary cataplexy refers to the characteristic episodes of sudden muscle weakness that are caused by an underlying health condition. For example, if the individual is walking when the attack begins that cannot control the simple movement during the attack, although they remain conscious. When this occurs during an active movement, a cataplectic attack can occur, when the loss of muscle control affects the fulfillment of the activity. The lack of muscle tone is thought to be caused by the widespread inhibition of motor neurons in the nervous system, particularly the spinal cord. It has been suggested that the cataplexy episodes are associated with muscular paralysis in the REM sleep cycle. The immune system is thought to be involved in this process and, in many cases, it is an autoimmune response triggered by an infection that causes the cell destruction. The reason for the destruction of the neurons that affect the production of hypocretin can vary greatly. In patients that suffer from cataplexy, these neurons are destroyed or disabled, which disrupts the production of hypocretin and can lead to episodes of cataplexy. There are several neurons in the hypothalamus that are usually involved in the process of production of hypocretin in the brain cells. Hypocretin in a neurotransmitter, also known as orexin, that plays an important role in the central nervous system to regulate the sleep-wake cycle and cause individuals to experience wakefulness. Increased levels of dopamine play an important role in transition to REM sleep, mice study suggests.FDA approves a new indication for chronic sleep disorder treatment.
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