Cataplexy

Cataplexy is a sudden loss of muscle tone caused by emotional stress or a state of affect - from a barely noticeable weakening of the muscles of the face and neck to total short-term atony and loss of the ability to hold the body in a certain position. In clinical neurology, cataplexy is usually considered one of the symptoms of such a disease of the nervous system as narcolepsy (Gelineau's disease).

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Causes cataplexies

Before considering the most important causes of cataplexy, it should be borne in mind that, according to the European Federation of Neurological Societies (EFNS), narcolepsy and cataplexy, or more precisely, cataplexy syndrome, is observed in an average of 70-80% of patients diagnosed with narcolepsy - increased daytime sleepiness. And this syndrome has nothing to do with pathologies of the musculoskeletal system, but is directly related to the human brain and central nervous system. This is primary cataplexy (or Levenfeld-Henneberg syndrome).

Scientific research over the last 15 years has shown that periodic inhibition of nerve impulse transmission and instantaneous decrease in muscle tone in this pathology occur due to problems with the hypothalamus. The currently accepted version of the etiology of narcolepsy and cataplexy is an insufficient number or destruction of hypothalamic cells that produce hypocretin (orexin), a neurotransmitter that regulates the processes of excitation and wakefulness. What exactly leads to the loss of brain cells that produce this neuropeptide has not yet been determined, but scientists agree that this is a genetically transmitted (modified form of the DQB1 0602 gene) pituitary pathology of an autoimmune nature.

According to the second version, cataplexy is caused not by a hypocretin deficiency, but by a defect in the receptors that perceive it. In general, the neurophysiological mechanism for the development of cataplexy remains unclear at present, although a certain relationship has been found between the deficiency of this mediator of the nervous system and a decrease in the level of such important hormones-neurotransmitters as histamine, dopamine and adrenaline. On this basis, this condition could be classified as a diencephalic syndrome of a dyshormonal nature.

Secondary cataplexy may occur as a result of damage to the hypothalamic region of the brain by tumors or metastases from breast, thyroid or lung cancer, due to congenital anomalies of the cerebral vascular system, multiple sclerosis, traumatic brain injury or infections.

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Symptoms cataplexies

Typical symptoms of cataplexy are expressed in the form of atonic muscle attacks lasting from several seconds to several minutes, during which a person - due to the disappearance of normal physiological muscle tension - experiences a drooping lower jaw, a lowering or throwing back of the head, bending of the legs at the knee joints ("buckling"), arms hanging along the body. In most cases, when a cataplexy attack occurs in a standing position, a person cannot stay on his feet and falls.

In this case, the person does not lose consciousness, breathing does not stop, but the heartbeat may slow down; the face becomes red, sweating; speech is inarticulate (due to the relaxation of the facial muscles and masticatory muscles). Vision also deteriorates: double vision (diplopia) and problems with focusing. But hearing and understanding are not impaired.

As experts note, atony can be partial, affecting only the muscles of the face and neck. The onset of symptoms most often occurs in adolescence or 20-30 years of age; in children, narcolepsy and cataplexy are diagnosed in less than 5% of cases, the overwhelming majority of patients are male.

In addition, the anamnesis of patients with cataplexy syndrome includes a short-term loss of muscle tone immediately after a night's sleep - the so-called awakening cataplexy, as well as disturbances in the normal structure of sleep in the form of anxiety, hallucinations when falling asleep and negative emotional coloring of dreams (often having all sorts of nightmares).

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Diagnostics cataplexies

Diagnosis of cataplexy is carried out by a neurologist and consists of:

• examining the patient, recording his complaints and collecting anamnesis;
• finding out all the patient’s illnesses and the medications he/she is taking;
• studying the characteristics of night sleep using polysomnography;
• establishing the level of biological need for sleep by conducting MSLT testing - multiple sleep latency testing (conducted no later than two hours after waking up from a night's sleep);
• identification of pathological sleepiness (hypersomnia) by means of questioning on the Epward sleepiness scale;
• electroencephalography (EEG);
• CT or MRI of the brain.

When making a diagnosis, it is necessary to strictly adhere to the diagnostic criteria accepted in neurology, since cataplexy requires differentiation with respect to fainting, epileptic seizures, drop attacks, transient ischemic attacks, vertebral artery syndrome, periodic hyperkalemic paralysis, acute intermittent porphyria, Thomsen's disease, Lambert-Eaton and Guillain-Barré syndromes, as well as iatrogenic intoxications of the body.

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Treatment cataplexies

Today, treatment of cataplexy - taking into account the clinical approach to the etiology of the disease - is carried out with drugs that control the manifestation of symptoms. But if cataplexy does not create significant problems for the patient, then no drug treatment is required.

Despite the lack of medical evidence of the effectiveness of antidepressants in the treatment of this pathology, the European EFNS recommendations assign antidepressants a key position in the tactics of cataplexy therapy. According to neurologists' prescriptions, Clomipramine should be taken - 10-20 mg per day. Selective serotonin and norepinephrine inhibitors and drugs that inhibit the reuptake of serotonin in nerve endings (SSRIs) can also be used. However, all of them, especially antidepressants, have a lot of negative side effects.

The American Academy of Sleep Medicine recommends a medication based on the sodium salt of gamma-hydroxybutyric acid for cataplexy - Sodium Oxybate or Sodium Oxybutyrate (syrup or solution for oral administration). The main area of use of this drug is anesthesiology (for non-inhalation anesthesia), ophthalmology (to improve vision in glaucoma), and in neurology - as a sedative to improve the quality of night sleep. Standard dosage: one tablespoon of syrup or 5% solution before bedtime. The drug undergoes complete biochemical transformation with metabolites in the form of water and carbon dioxide, but prolonged use can cause increased potassium levels in the body.

Since sodium oxybate can cause daytime sleepiness, stimulant drugs are prescribed simultaneously with it - in particular, Modafinil (other trade names - Modalert Alertek, Provigil) based on the active substance 2-(diphenylmethyl)-sulfinyl acetamide. The drug is taken once a day (in the morning) for diagnosed narcolepsy with frequent attacks of cataplexy. This drug is contraindicated in patients under 18 years of age, in the presence of psychosis, depression, suicidal thoughts or mania; blood pressure and pulse rate should be monitored.

Prevention

Prevention of cataplexy is more of a general health-improving nature, since the disease is incurable. Doctors advise giving up coffee, alcoholic and alcohol-containing drinks, quitting smoking, and also doing physical exercise, eating a balanced diet, and not overworking.

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Forecast

Prognosis of cataplexy: with inadequate night sleep, memory and concentration may be significantly impaired; difficulties (and dangerous situations) may arise when driving or operating complex mechanisms. In addition, with an unexpected fall during atonic muscle attacks, a person may receive a serious injury, primarily a craniocerebral injury.

Typically, the symptoms of narcolepsy and cataplexy persist throughout life. However, sometimes - over time or as a result of therapy - cataplexy disappears.