One of the most characteristic symptoms of narcolepsy are the episodes of cataplexy, during which the muscles relax and weaken suddenly , sometimes even causing falls and accidents.

In this article we will explore the causes of cataplexy and the treatments that prevent its symptoms, both pharmacological and psychological.

Definition of cataplexy

We call “cataplexy” or “cataplexy” the transient episodes of muscle weakness that occur in some people . They are considered an intrusion of the processes that regulate sleep in the waking state, although during cataplexy the person maintains consciousness.

These symptoms usually occur as a result of intense emotions; for example, it is common for loss of muscle tone to occur when the person laughs a lot, feels afraid or cries.

Episodes of cataplexy occur almost exclusively in the context of narcolepsy , so we can consider them a cardinal symptom of this disease. Cataplexy is very rare without narcolepsy.

What is narcolepsy?

Narcolepsy is a sleep disorder characterized by the appearance of elements of REM (rapid eye movement) sleep in wakefulness. Its most characteristic symptom is the occurrence of sleep attacks despite adequate rest .

In addition to sleep access and cataplexy, other common symptoms of narcolepsy are daytime hypersomnolence, sleep disturbance during the REM phase, and the occurrence of hypnagogic hallucinations and sleep paralysis during wakefulness.

Cases of narcolepsy do not always include cataplexy , but these episodes occur in 70% of narcoleptic people. When cataplexy is present, there is almost always a deficit of the hormone hypocretin, another of the fundamental signs of narcolepsy.

Symptoms

The episodes of cataplexy are brief; most times they last less than two minutes . They are usually the result of physical efforts or strong emotions, especially if they occur unexpectedly.

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Muscle weakness is variable and may be limited to relaxation of the knees or jaws or involve transient paralysis of the entire body. This can lead to falls or accidents, for example if the person is driving.

The episodes of cataplexy should not be confused with the sleep attacks also characteristic of narcolepsy: during cataplexy the person maintains consciousness, although if he or she is in a comfortable position he or she may feel sleepy and even fall asleep as a result of the relaxation.

Other symptoms that commonly occur during cataplexy episodes are pronunciation difficulties and visual disturbances, particularly blurred or double vision.

Causes of these alterations

The main cause of narcolepsy and cataplexy is considered to be low levels of the hormone orexin or hypocretin in the spinal fluid. Orexin plays a major role in maintaining alertness and vigilance; its deficit has been linked to the REM intrusions typical of narcolepsy.

In particular, episodes of cataplexy are believed to result from sudden and widespread inhibition of motor neurons at the spinal cord level, causing a loss of muscle control.

Any alteration that reduces orexin levels is likely to cause narcoleptic symptoms such as cataplexy. Thus, these episodes can occur as a result of lesions, malformations and brain tumours .

Brain infections, strokes, or diseases such as multiple sclerosis can also cause episodes of cataplexy. Damage to the hypothalamus, which secretes hypocretin, is often implicated in the development of this disorder.

In many cases narcolepsy and cataplexy have a genetic component. In this sense, many experts consider narcolepsy an autoimmune disorder related to the so-called “human leukocyte antigens” (HLA).

Treatment and prevention

Cataplexy is mainly treated with drugs . The treatment of choice is sodium oxybate, a very safe drug that is also effective in combating daytime sleepiness. Gamma-hydroxybutyrate has similar effects.

Other drugs used in cases of cataplexy and narcolepsy in general are stimulants, such as modafinil, and antidepressants , particularly tricyclics and venlafaxine, a selective serotonin and noradrenaline reuptake inhibitor.

Psychology can also contribute to the treatment of cataplexy. In this sense, interventions are focused on the prevention of these episodes from the identification of the symptoms that precede them: learning to detect the prodromes of cataplexy is useful to be able to react to them when they start to occur in the future.

To reduce symptoms of narcolepsy, including cataplexy and drowsiness, scheduling short daytime naps and maintaining healthy sleep habits are recommended.

Bibliographic references:

  • Seigal, Jerome (2001). Narcolepsy. Scientific American: 77.
  • van Nues SJ, van der Zande WL, Donjacour CE, van Mierlo P, Jan Lammers G. (2011). The clinical features of cataplexy: A questionnaire study in narcolepsy patients with and without hypocretin-1 deficiency. Sleep Medicine.