Narcolepsy is a sleep disorder. The principal symptoms are excessive daytime sleepiness (EDS), cataplexy (loss of muscle tone), hypnagogic hallucinations, sleep paralysis, disrupted night-time sleep and automatic behaviour (being unaware of what you are doing). A person suffering from narcolepsy may have some or all of these symptoms.

Excessive daytime sleepiness usually occurs every day, regardless of the amount of sleep obtained at night. EDS is usually experienced as a heightened sensitivity (sometimes an almost irresistible susceptibility) to becoming sleepy or falling asleep, especially in sleep-inducing situations, such as sitting in a comfortable chair.

Patients describe the problem as sleepiness, tiredness, lack of energy, exhaustion or a combination of these feelings, either continuously or at various times throughout the day. Sometimes sleepiness occurs so suddenly and with such overwhelming power that it is referred to as a ‘sleep attack’ . Some people have many ‘sleep-attacks’ each day, the duration ranging from a few seconds to several minutes, and may be unaware of their occurrence. Occasionally attacks may last for several hours. Narcoleptic sleep attacks are thought by some authorities to be the inappropriate appearance of REM sleep.

Cataplexy is an abrupt loss of voluntary muscle tone, usually triggered by emotional arousal. Attacks can range in severity from a brief sensation of weakness to total physical collapse lasting several minutes. Hypnagogic hallucinations are intense, vivid dreams, sometimes ccompanied by frightening auditory, visual and tactile sensations, and usually occur just on wakening or falling asleep, but may occur at other times. They are often xtremely difficult to distinguish from reality.

 
Sleep paralysis is the inability to move when waking up or falling asleep. This may be momentary, or longer, or multiple attacks may occur. This condition can be terrifying, especially if it occurs with a frightening hypnagogic hallucination.

Narcolepsy, or a predisposition to it, is usually an inherited condition, but has occurred after Head injury or brain damage caused by severe infection. The prevalence of narcolepsy is estimated to be 1-2 per 2000.

Cataplexy Symptoms

With the help of unexpected and sudden loss of skeletal muscle tone (weakness or paralysis), cataplexy can be categorized. It is extremely unpredictable both in severity and frequency. Cataplexy may occur occasionally but may occur many times a day.

Muscle tone loss varies from mild to severe. The usual duration is from a few seconds to several minutes. Cataplexy may be partial or complete, affecting a range of muscle groups, from those controlling facial features to (less commonly) those controlling the entire body.

 
• Arm weakness  
• Sagging jaw  
• Drooping head  
• Slumping of the shoulders  
• Slurred speech  
• Generalized weakness  
• Knee buckling

Essentially, cataplexy is a symptom only found in narcolepsy and therefore, the presence of cataplexy makes narcolepsy diagnosis much more certain. Easily overlooked and frequently undiagnosed, cataplexy may affect the most basic activities of daily living.

By impairing primary functions like talking, eating, standing, walking, or driving, it can prevent patients from experiencing important activities such as holding a child, going to a movie, interviewing for a job, attending a party, participating in a meeting, or working out at the gym.

Even mild to moderate cataplexy symptoms or the fear of those symptoms can bound activities.

Symptoms cause humiliation and loss of self-esteem, leading to less social interaction, difficulty with interpersonal relationships, and depression. Symptoms of narcolepsy, including cataplexy, have been shown to have a severe impact on quality of life.

Progress of Symptoms

Narcolepsy is a lifelong illness. There is no known cure and no report of lasting remission has been confirmed. Typically, symptoms (usually EDS) first become noticeable between the ages of 10 and 30, although a number of cases have been diagnosed as infants and many are only diagnosed much later. Symptoms are usually subtle at first but become more obvious over a few years. They then usually stabilize, especially when adequately treated.

Narcoleptics usually are able to control the symptoms with adequate medication and correct diet. Driving or operating machinery, while dangerous for untreated narcoleptics, should not be a problem if medication and diet schedules are adhered to. Narcolepsy does not affect longevity of life.

Social Complications

The mild early symptoms of narcolepsy may cause no more than minor inconveniences. More severe symptoms will cause greater disruptions in one’s social and professional life. EDS and/or sleep attacks often occur at inopportune times - in the classroom, at business meetings, during a meal, or even in the middle of a conversation. The ability to learn, for children and adults alike, is hampered because the abilities to read, study or concentrate are periodically (or continuously) impaired by sleep attacks or other symptoms. Parents, teachers, spouses, and employers often mistake the person’s sleepiness for lack of interest, or construe it as a sign of hostility, rejection, or laziness. Early diagnosis and treatment are important to obtain maximum quality of life.

Cataplexy attacks commonly occur in situations involving perfectly normal emotions such as humour (hearing or telling a joke); competitiveness (about to make set-point at tennis); excitement (barracking at the footy); and stress or self-assertion. A person’s efforts to stave off cataplectic attacks by avoiding these emotions may greatly diminish their lives, and they may become severely restricted emotionally if diagnosis and treatment is not begun as soon as possible.

Diagnosis

Diagnosis may be difficult in many cases as some symptoms develop slowly. Many people have narcolepsy for 10 to 15 years or more before the disorder is correctly diagnosed. In many cases a medical disorder is not suspected and so help is not sought until symptoms are quite severe. Also physicians often misdiagnose narcolepsy, mistaking the symptoms for those of other disorders, like depression, chronic fatigue syndrome, or obstructive sleep apnoea. Up to 50% of persons with narcolepsy develop mixed sleep apnoea but treatment for OSA alone is not adequate without treating the primary condition, narcolepsy, at the same time. Sometimes the sleepiness is thought to be a side-effect of a medication. Cataplectic attacks have also been misdiagnosed as epileptic seizures, even though narcolepsy is not a form of epilepsy and requires different treatment. Narcolepsy may usually be confirmed by a sleep study (polysomnography) and a Multiple Sleep Latency Test (MSLT) but this is not always definitive and diagnosis may require careful consideration of the presenting symptoms over a period of time. The care of a person with narcolepsy should be multi-faceted, requiring coordinated treatment by a neurologist, respiratory specialist, neuropsychologist and support group to counteract effects caused by misdiagnosis, late diagnosis or problems associated with lifestyle changes required.

Treatment
Treatment is with stimulant drugs to suppress daytime sleepiness, antidepressants for cataplexy, and gamma hydroxybutyrate for both symptoms. Because narcolepsy is an under-recognised disease, it is important that general practitioners and other primary health-care workers identify abnormal daytime sleepiness early.

Although there is no known cure for narcolepsy, several medications help to control the symptoms. Stimulants are usually prescribed to treat EDS and sleep attacks, and usually control most other symptoms. In some cases certain anti-depressants taken at bedtime may be required to aid in control of cataplexy.

Narcolepsy symptoms vary from person to person, as does response to medications; also both symptoms and response are likely to change at different times in life. The proper choice of medication and dosage requires careful attention to the person’s needs and responses, and close cooperation between patient and medical personnel. The medications used to control narcolepsy are usually very helpful but may cause some side effects. These can be controlled in most cases.

  * Short naps may be helpful to some people. Regular sleep hours and avoidance of sleep deprivation are very important.
  * Large meals should be avoided during the day and smaller, more frequent, low carbohydrate meals substituted.
  * Changes to lifestyle may be required, but the aim is to ‘fit’ the treatment to accommodate the normal physical and mental demands of school/work and family life.

Dauvilliers Y, Arnulf I, Mignot E.

Neurologie, CHU Montpellier Hopital Gui-de-Chauliac and INSERM U888, Montpellier-France. .(JavaScript must be enabled to view this email address)