Narcolepsy is a sleep pathology characterized by a violation of the sequence of sleep phases and the occurrence of a rem sleep phase during wakefulness. The main symptom of the disease is attacks of irresistible sleep, forcing the patient to literally “fall asleep on the spot.” Typical signs of narcolepsy also include cataplexy, sleep paralysis and hypnagogic phenomena. The basis of the diagnostic search is polysomnography, MSLT test and examinations aimed at excluding other types of hypersomnia. Treatment of narcolepsy is aimed at normalizing the rhythm of sleep and wakefulness, reducing daytime sleepiness and manifestations of cataplexy, improving night sleep.
ICD 10
G47.4 Narcolepsy and cataplexy
General information
Narcolepsy is a rare sleep disorder of the type of hypersomnia (increased drowsiness), manifested by a deterioration in the quality of night sleep and the appearance of paroxysmal attacks of falling asleep during active wakefulness. Narcolepsy is possible at any age, but it usually manifests in the period from 15 to 25 years. The frequency of its diagnosis according to various data is 20-40 cases per 100 thousand people. In modern medicine, narcolepsy has several synonyms: Gelino’s disease, narcoleptic disease, essential narcolepsy.
Etiology and pathogenesis
While scientific and clinical neurology does not have accurate information about the causes and mechanisms of the formation of narcolepsy. The previously widespread assumption that sleep regulation disorders in narcolepsy are directly related to mental disorders and psychological problems is now recognized as untenable. The theory is put forward that the disease is caused by the insufficiency of the neurotransmitter responsible for maintaining the state of wakefulness. Hypocretin (orexin) is considered as such a biologically active substance. Orexin deficiency can be genetically determined or occurs when exposed to such trigger factors as severe infections, severe fatigue, traumatic brain injury, pregnancy, endocrine dysfunction.
According to another theory, narcolepsy may have an autoimmune mechanism of occurrence, which is confirmed by the presence of abnormal T-lymphocytes absent in healthy people, cases of the disease after vaccination and its association with various infectious diseases (influenza, measles, etc.).
Little is known about the pathogenesis of narcolepsy. The similarity of the state of the muscular system in the phenomena of cataplexy and sleep paralysis with its state in the rem sleep phase, as well as the appearance of the rem sleep phase when falling asleep or immediately after it, suggest that the main problem of narcolepsy is the untimely occurrence of the rem sleep phase — its introduction both in the slow sleep phase and during wakefulness.
Narcolepsy symptoms
The basis of the clinical manifestations of narcolepsy is hypnolepsy — an attack (attack) of irresistible sleep (hypnos — sleep, lepsis — attack). The patients themselves describe this condition as very severe drowsiness, inevitably leading to falling asleep. Such attacks often develop in a monotonous environment and when performing monotonous actions (for example, while listening to a lecture, reading, watching TV). Drowsiness in such situations can also be observed in healthy people. In contrast, in a narcolepsy patient, sleep attacks also occur at moments of intense activity (when eating, talking, driving a car).
The frequency of hypnolepsy attacks varies significantly, their duration can range from a few minutes to 2-3 hours. Waking up a person during narcoleptic sleep is as easy as during normal sleep. After waking up, a patient with narcolepsy, as a rule, feels quite cheerful. However, after a few minutes, the next sleep attack may occur with him. Over time, patients adapt to their disease and, feeling characteristic drowsiness, manage to find a more or less suitable place to sleep.
Along with the attacks of hypnolepsy that occur during the daytime, narcolepsy is characterized by a disorder of night sleep. Typical are vivid dreams, frequent interruptions of night sleep, insomnia, a feeling of lack of sleep in the morning. Poor-quality night sleep leads to a decrease in performance and the ability to concentrate attention, the appearance of daytime drowsiness and irritability, increased interpersonal conflicts, the emergence of depressive neurosis, chronic fatigue syndrome.
In the process of falling asleep or before waking up, hypnagogic phenomena are possible in patients with narcolepsy — vivid visions, visual and auditory hallucinations, often of a threatening nature. These phenomena are similar to dreams that occur during the rem sleep phase. Normally, they are noted in young children, in rare cases — in healthy adults.
In 25% of patients with narcolepsy, sleep paralysis is observed — a transient muscle weakness that does not allow a person to make arbitrary movements and occurs when falling asleep and waking up. Many patients note that during this period they experience a strong sense of fear. It is noteworthy that muscle hypotension in sleep paralysis resembles the state of skeletal muscles during the rem sleep phase.
Approximately 75% of cases of narcolepsy have attacks of sudden short—term muscle weakness up to complete paralysis – cataplexy. Usually cataplexy is provoked by sharp emotional reactions of the patient (surprise, joy, anger, fear, etc.). Muscle weakness may have a generalized character, then the patient with narcolepsy falls as if knocked down, or cover only part of the body (for example, only an arm or both hands).
Diagnostics
Examination of patients with complaints characteristic of narcolepsy is usually carried out by a neurologist. Diagnostic search includes polysomnography with EEG registration and multiple sleep latency test (MSLT test). A more in-depth study of sleep by means of a special somnological laboratory is carried out by a somnologist.
Polysomnography examines night sleep, for which a patient with suspected narcolepsy will have to spend the whole night in a specially equipped office under the supervision of a doctor. Polysomnography allows you to identify violations of the alternation of sleep phases with an increase in the frequency and duration of the rem sleep phase with rapid movements of the eyeballs and exclude other possible sleep disorders (including sleep apnea syndrome).
The MSLT test is usually scheduled for the day following polysomnography. During the study, the patient is asked to make 5 attempts to fall asleep during the day, the interval between sleep attempts is 2-3 hours. The criteria for confirming narcolepsy are: the presence of at least two episodes of confirmed sleep and a reduction in the latent sleep onset time to 5 minutes.
Additionally, the determination of periods of latent drowsiness can be carried out, in some cases allowing to assess the effectiveness of the treatment.
It is necessary to differentiate neurolepsia from epilepsy, other types of hypersomnia: psychophysiological; post—traumatic — caused by a previous TBI, the presence of intracerebral hematoma; psychopathic – occurring against the background of mental disorders (schizophrenia, hysteria); associated with inflammatory (encephalitis, meningitis, arachnoiditis), tumor or vascular (chronic cerebral ischemia, aneurysm, ischemic and hemorrhagic stroke) cerebral diseases, as well as with somatic pathology (hypothyroidism, diabetes mellitus, liver failure, pernicious anemia, etc.). In the course of differential diagnosis, it may be necessary to consult a psychiatrist, epileptologist, endocrinologist, infectious disease specialist, gastroenterologist; ophthalmoscopy, MRI of the brain, duplex scanning, MRA or ultrasound of cerebral vessels.
Narcolepsy treatment
Patients with narcolepsy are recommended to adhere to a constant sleep regime, i.e. falling asleep and waking up at the same time. For most patients, the most acceptable scheme is one that includes a 7-8-hour night’s sleep and 2 daytime naps lasting from 15 to 30 minutes. In order to improve the quality of night sleep, it is necessary to avoid eating heavy food and alcohol, as well as eating before going to bed. If you have narcolepsy, you should not drive vehicles, work in dangerous conditions or with any mechanical devices.
Treatment of narcolepsy with mild or moderate daytime drowsiness begins with modafinil, which, stimulating the state of wakefulness, does not cause euphoria, addiction syndrome and aftereffects. The initial dose is 1 time in the morning. If the action of modafinil is not enough to stop the symptoms of narcolepsy for the whole day, an additional daily intake of the drug is allowed.
In cases where neurolepsia does not respond well to treatment with modafinil, they resort to prescribing amphetamine derivatives: methylphenidate or dexamphetamine, methamphetamine. However, they have side effects such as tachycardia, agitation, hypertension, addiction with the risk of addiction (see Amphetamine abuse).
The use of tricyclic antidepressants (clomipramine and imipramine), a serotonin reuptake inhibitor (fluoxetine) helps to reduce the frequency of cataplexy in patients with narcolepsy. In the treatment of narcolepsy, modafinil, methylphenidate and a number of other drugs are also used. Nasal spray is being developed, which, according to scientists, will allow patients with narcolepsy to quickly make up for the neurotransmitter deficiency and thereby avoid attacks of hypnolepsy.
Prognosis and prevention
The disease is lifelong. Significantly affecting the quality of life of patients, narcolepsy does not cause a reduction in its duration. Adequately prescribed therapy can significantly reduce the manifestations of narcolepsy, but the need for constant medication leads to the manifestation of their side effects.
Since the causes and mechanisms of narcolepsy are not known for certain today, its specific prevention cannot be developed.
