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Sounding the alarm for narcolepsy

QUILLEN, TERRILYNN FOX RN, BS

HEALTH MATTERS: Promoting health and wellness
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NARCOLEPSY IS COMMONLY diagnosed after a person falls asleep while driving and has an accident. Once thought to be rare, it affects more than 135,000 Americans, but many of them are unaware of their condition. Chronic sleepiness is often mistakenly attributed to other causes, explaining why the average delay between symptom onset and diagnosis is 10 to 15 years.

Because it's linked to accidents, narcolepsy can be hazardous to your patient's health. Here, I'll explain how to assess for it and steer your patient to safety.

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More than an after-lunch slump

Although some children have been diagnosed with narcolepsy, symptoms usually begin during puberty or young adulthood. According to the Stanford University School of Medicine Center for Narcolepsy, it's the second leading cause of excessive daytime sleepiness (EDS), behind obstructive sleep apnea.

The EDS of narcolepsy is unlike the ordinary drowsiness experienced after a big lunch. Persistent and irresistible, the EDS of narcolepsy may overtake the patient without warning, causing sudden, brief moments of slumber. Also called microsleeps, these sleep attacks can occur during a meaningful activity, such as eating, talking, and even sexual intercourse. After sleeping for minutes (sometimes hours), the patient may awaken feeling refreshed or dazed.

During microsleeps, people may have automatic behavior, or a period of poor concentration or foggy thinking characterized by routine, complex, or bizarre automatic behavior. Examples include continuing to type, driving to an unintended location, or putting dishes into the washing machine instead of the dishwasher.

People with narcolepsy may awaken frequently during the night, but this isn't the primary cause of their EDS. Rather, EDS may be the reason for fragmented nighttime sleep.

Sleep attacks and EDS are the main symptoms of narcolepsy, but other hallmarks include the following:

  • cataplexy—a sudden brief loss of muscle tone, leading to a feeling of weakness or total loss of voluntary muscle control. It's similar to the interruption of muscle activity that occurs normally during rapid eye movement (REM) sleep. Cataplexy is sometimes triggered by intense emotion or laughter. About 70% of people with narcolepsy also have cataplexy. For about 10% of patients with narcolepsy, cataplexy is the first symptom they have. Sometimes these people are misdiagnosed as having a seizure disorder.
  • sleep paralysis—a temporary inability to move or speak without loss of consciousness when awakening or falling asleep
  • hallucinations—usually visual, they may occur with sleep paralysis or while falling asleep or waking up.

Narcolepsy is probably caused by a deficiency of hypocretin-1 and hypocretin-2, neurotransmitters produced by the hypothalamus. This deficiency may result from an autoimmune response caused by genetic or environmental factors. Injuries to parts of the brain involved in REM sleep may play a role in the development of narcolepsy.

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Confirming the diagnosis

A preliminary diagnosis of narcolepsy may be made based on physical examination and a comprehensive history. Practitioners may administer the Stanford Narcolepsy Questionnaire or Epworth Sleepiness Scale in outpatient settings.

The diagnosis should be confirmed in a sleep disorder center by the overnight polysomnogram and a multiple sleep latency test (MSLT). The polysomnogram simultaneously records electroencephalogram (EEG), cardiac rate and rhythm, electromyelogram (EMG), electrooculogram (EOG), respiratory rate, blood pressure, and Spo2. This test helps identify whether REM sleep occurs at abnormal times in the sleep cycle and can rule out other causes for EDS, such as obstructive sleep apnea.

The MSLT records heart and respiratory rates, EEG, EMG, and EOG during scheduled daytime naps. Rapid (less than 5 minutes) REM-onset sleep occurring in at least two of four or five daytime nap periods during the MSLT suggests narcolepsy.

A maintenance of wakefulness test (MWT) can be administered to evaluate the effectiveness of treatment and to support the patient's ability to return to employment or resume driving if his driver's license was revoked. The MWT, which measures his ability to stay awake while sitting up, includes EEGs and measurements of chin muscle activity and eye movements.

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Stimulating choices

Although there's no cure for narcolepsy, drug treatment can control EDS and cataplexy. Many drugs used to treat narcolepsy and cataplexy can be abused, so proper diagnosis and patient teaching are essential

Historically, narcolepsy was treated with central nervous system (CNS) stimulants. Adverse reactions to CNS stimulants include arrhythmias, nighttime sleep disruptions, irritability, and nervousness. Some patients develop tolerance after long-term use. Modafinil (Provigil) is now the treatment of choice because it's effective in alleviating EDS with fewer and less-serious adverse reactions.

According to the National Institute of Neurological Disorders and Stroke, two classes of antidepressants—tricyclics and selective serotonin reuptake inhibitors—are effective in controlling cataplexy in many patients.

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Supporting your patient

Some patients are relieved to finally have a diagnosis for their symptoms; others are shocked. Not all patients will accept prescribed medication.

You can help a patient cope with his condition by offering education and emotional support, helping him develop good sleep habits and coping strategies, teaching him about his medications (including risks and benefits), and making referrals for additional support.

School and occupational health nurses may need to advocate for students and employees diagnosed with narcolepsy. Under Title II of the Americans with Disabilities Act, they're considered disabled and entitled to reasonable accommodation in school or the workplace.

By being alert to the symptoms of narcolepsy and encouraging your patient to seek testing and treatment, you may be able to keep him safe from harm.

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SELECTED WEB SITE

Stanford University School of Medicine Center for Narcolepsy http://med.stanford.edu/school/Psychiatry/narcolepsy

Narcolepsy Network, Inc. http://www.narcolepsynetwork.org

Last accessed on May 9, 2005.

Terrilynn Fox Quillen is a faith community nurse and freelance writer in Greenwood, Ind.

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SELECTED REFERENCES

Feldman NT. Narcolepsy. Southern Medical Journal. 96(3):277–p282, March 2003.
Landis CA. Sleep and methods of assessment. Nursing Clinics of North America. 37(4):583–597, December 2002.
NIH Publication No. 03-1637. Last updated on March 8, 2005.National Institute of Neurological Disorders and Stroke. Narcolepsy Fact Sheet.
    © 2005 Lippincott Williams & Wilkins, Inc.