Narcolepsy
Narcolepsy is characterized by a tetrad of symptoms that includes excessive daytime sleepiness (EDS), cataplexy, sleep paralysis and hypnagogic hallucinations. This disease affects one in 2000 people in the general population, is typically marked by permanent and overwhelming feeling of sleepiness and fatigue.1 Narcolepsy usually manifests between the ages of 10 and 25 years.
Causes
Research had suggested that narcolepsy is caused by the lack of a chemical in the brain called hypocretin. This chemical stimulates brain cells and helps promote wakefulness. Although it is not known why hypocretin is deficient in people with narcolepsy, few factors, which may cause lack of hypocretin had been identified. These include the following:
- Infection
- Loss of certain brain cells due to brain injury, toxins and/or autoimmune reaction
- Hormonal changes
- Stress
- Genetic linkage
Symptoms
- Excessive daytime sleepiness is a persistent sense of mental cloudiness, lack of energy or extreme exhaustion. Many reported difficulty in concentrating while at school or work.
- Cataplexy is a sudden episode of muscle weakness triggered by emotions. Typically, the patient’s knees buckle and give way upon laughing, surprise or anger. In others, the head may drop or the jaw may become slack. The patient might fall down and become paralyzed for a few seconds to several minutes. The person remains conscious throughout the episode.
- Sleep paralysis is the temporary inability to talk or move when waking which may last a few seconds to minutes.
- During hypnagogic hallucinations, patients experience dream-like auditory or visual hallucinations, while dozing or falling asleep.
In majority cases, the first symptom of narcolepsy to appear is EDS, which occurs even after adequate nighttime sleep. The other symptoms begin alone or in combination in months or years after the onset of the daytime naps. The EDS generally persists throughout life but sleep paralysis and hypnagogic hallucinations may disappear after some time.
Treatment
As EDS is common and associated with a broad range of medical, psychiatric and sleep disorders, accurate diagnosis of narcolepsy and comorbid disorders is important for optimal treatment response. Narcolepsy is a lifelong condition. Although there is no cure for this condition, symptoms often improve with ongoing treatment.
Pharmacologic management is based on symptomatic treatment of cataplexy and EDS. The most widely used medications for cataplexy include the antidepressants venlafaxine, imipramine and protriptyline, usually at doses lower than that prescribed for depression. The US Food and Drug Administration (FDA) has approved four medications for EDS: dextroamphetamine, methylphenidate, modafinil (a non-amphetamine wake-promoting drug) and sodium oxybate (a short-acting sedative).2 Sodium oxybate is the only drug approved for treating both cataplexy and EDS.
In addition to drug therapy, an important part of treatment is scheduling short naps (10–15 min) 2–3 times per day to help control EDS and to help the person stay as alert as possible. Most people with narcolepsy can lead productive lives with proper medical care and lifestyle changes. They should avoid jobs that require driving long distances or handling hazardous equipment.
Written by: Healthplus24 team
Date: Jan28th,09
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