Narcolepsy: Definition, Symptoms and Treatment

Narcolepsy: Definition, Symptoms and Treatment

By Arkemmus | Arkemmus' Blog | 30 Apr 2021

Narcolepsy is a serious disorder of sleep awakening rhythm - which usually begins in childhood or adolescence and has a similar incidence in men and women. Some patients may have a history of encephalitis or craniocerebral trauma. Most patients are accompanied by other symptoms such as cataplexy, excessive daytime sleepiness, sleep paralysis, sleep hallucinations, collectively called "narcolepsy tetrad". Many studies have suggested that narcolepsy is caused by a physical illness. In 2014, the International Classification of Sleep Disorders (ICSD) differentiated narcolepsy into type Ⅰ and type Ⅱ. The incidence of narcolepsy is 30 / 100,000, with the highest incidence in Japan (160 / 100,000), the lowest in Israel (0.23 / 100,000) and Saudi Arabia (4 / 100,000) .


Clinical manifestations of narcolepsy

The onset age of narcolepsy is usually 10 to 20 years old, with a peak at 15 years. Onsets are rare after the age of 40 and before the age of 10.


Performance of narcolepsy tetralogy:

Sleep onset: manifested at any time, characterized by an active state of irresistible sleep episodes, which last from minutes to tens of minutes, occurring repeatedly many times a day. This may be accompanied by a temporary loss of consciousness. It can occur while reading, watching TV, cycling or driving, attending class, eating or walking. In short, anything.

A short nap (10-30 minutes) is often inevitable.

Sudden attacks, often caused by strong emotional stimuli.
There is a sudden loss of body muscle tension but clear consciousness; it does not affect breathing, usually seizures last a few seconds and patients fall asleep soon after the seizure, then recovering completely. Attacks in children often involve facial muscles, leading to what is known as a cataplectic face.

  • Loss of energy, drooping eyelids, open mouth attacks, protruding tongue and grimace. Sudden attacks in children often last for several minutes and can be cluster-like.

  • Sleep paralysis: It is a phenomenon, lasting from seconds to minutes, that occurs when waking up from REM sleep. It is characterized by the inactivity of speech and breathing, with eye movements unaffected. This usually occurs after waking up in the morning, with clear consciousness during the attack, which can relieve itself. There is no memory impairment and very often are accompanied by anxiety attacks. Familial seizures have also been reported in this kind of sleep palsy.

  • Sleep hallucinations: auditory hallucinations, tactile hallucinations, and visual hallucinations; patients may feel that non-existent people are in their room or are touching them. It can occur in the transition from wakefulness to sleep (pre-sleep hallucinations) or from sleep to wakefulness (post-wake hallucinations), and is mostly a quite vivid unpleasant feeling experience. Other common symptoms include periodic limb movements, memory loss, aggressive behavior, and mental symptoms.

The clinical description of narcolepsy may differ in different populations and cultural backgrounds. For example, at the Stanford Sleep Center, Asian patients have fewer sudden onset attacks, and more often have negative emotions such as irritability.
American patients have more atypical cataplexy.


Diagnosis of narcolepsy

The revised International Classification of Sleep Disorders (ICSD-3) sets out diagnostic criteria for narcolepsy. Type I narcolepsy must have the following two:

  1. The patient has symptoms of excessive daytime sleepiness for (at least) 3 Months;

  2. Have at least one of the following two, a. Sudden onset, multiple sleep latency tests showing sleep latency ≤ 8 minutes in two or more sleep-initiated REM sleep episodes; b. Cerebrospinal fluid (CSF) hcrt concentration <1/3 of normal control value.


Type Ⅱ narcolepsy must have the following 5 items:

  1. The patient has excessive daytime sleepiness with symptoms of at least 3 months;

  2. Multiple sleep latency tests showing that the sleep latency is ≤ 8 min, and two or more sleep-initiating rapid eye movement sleeps occur;

  3. No sudden onset;

  4. The cerebrospinal fluid hcrt concentration was not detected or detected > 1/3 average normal control value;

  5. The symptoms of drowsiness cannot be explained by other diseases.




Differential diagnosis of narcolepsy


  1. Seizures are more common in children or adolescents, with the main symptoms of disturbance of consciousness (often a sudden loss of consciousness), staring straight, standing still, not falling; or sudden ending of ongoing actions. The patient is not able to continue the original action and this condition can last for several seconds. In such cases, the EEG can have a 3 Hz spine-slow synthesis wave.

  2. Fainting transient loss of consciousness due to a disturbance of cerebral blood circulation. Many short-term signs of dizziness, weakness, nausea, and dark eyes can unfortunately lead to loss of consciousness and death. It is often preceded by autonomic symptoms such as paleness, cold sweat, weak pulses, and decreased blood pressure.

  3. Kleine-Levin Syndrome, also known as periodic lethargy and pathological hunger syndrome. It is usually seen in male adolescents, with periodic attacks (intervals of several weeks or months), each lasting 3 to 10 days, manifested as lethargy, bulimia, and abnormal behavior. The etiology and pathogenesis are unknown and may be caused by abnormalities in the midbrain, especially in the lower thalamus, or focal encephalitis.

  4. Idiopathic hypersomnia. This disease is similar to narcolepsy, but daytime drowsiness can be controlled. Once the patient starts to sleep, it can last a long time, exceeding 12 hours in 24 hours. It often has a family history.



Treatment of narcolepsy


  1. Lifestyle changes. The main treatment of narcolepsy is to improve the quality of life of patients and help them integrate into society. Patients with narcolepsy generally believe that taking a nap can help them regain energy. Therefore, clinicians should advise patients to communicate better with the others (for example with their employers), avoiding choosing industries that work long intermittent hours, etc. But in general, adjusting life habits alone is not enough for patients, and most of them still need medication.

  2. Drug treatment is mainly divided into treatments for excessive sleep and treatments for the prevention of sudden falls. Modafinil is currently the more commonly used drug and is considered helpful to control dopaminergic activity in the hypothalamus. Histaminergic and adrenergic neurons all have stimulating effects to promote the maintenance of arousal state. The worse side effects of this drug are adverse dry mouth, headache, anxiety, insomnia, which can be tolerated in more than 67% of patients. Currently approved by the FDA (US Food and Drug Administration) for use in children. Another commonly used drug is γ-hydroxybutyrate, which is prescribed to prevent cataplexy. Studies have shown that the combination of γ-hydroxybutyrate and modafinil is better than the latter alone. However, due to its strong addiction, it should be used with caution in clinical practice. Other drugs mainly used as antidepressant and anti-Parkinson's disease treatment are effective for narcolepsy by chance. This is generally not the first choice and can be considered only in the case of patients with depression and Parkinson's disease.

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