Diagnosis

Although narcolepsy is a physical disorder, doctors are still very likely to misdiagnose patients as having psychological problems. For most patients, narcolepsy is not diagnosed for up to 10 - 15 years after their symptoms first began. To determine specific sleep disorders, the doctor will take a medical and family history and should be told of any medications a person takes. The symptoms of narcolepsy are sometimes undeniable if the patient reports all of the major symptoms:

• Excessive daytime sleepiness with a tendency for frequent naps. (These frequent naps should occur every day for at least 6 months to serve as a diagnosis of narcolepsy.) Narcolepsy is usually diagnosed in adolescence and young adulthood when falling asleep suddenly in school brings the problem to attention.
• Cataplexy (abrupt loss of muscle tone or weakness that causes a person to stop all motor activity).
• Hypnagogic hallucinations (vivid visual or auditory phenomena) experienced at the onset of sleep.
• Sleep paralysis (an inability to move on first awakening).

Diagnosis based only on symptoms, however, is often problematic for various reasons:

• Patients often seek medical help for single symptoms (sleep paralysis or hypnagogic hallucinations) that might be associated with other disorders, particularly epilepsy.
• Symptoms are sometimes not dramatically apparent for years, even to the patient or a skilled observer. In some cases, the patient may need to consult a sleep specialist or go to an accredited sleep disorder center for accurate diagnosis of a sleep disorder. Patients should carefully investigate centers to make sure that they offer full sleep studies. Patients who visit a sleep center undergo an in-depth analysis, usually supervised by a multidisciplinary team of consultants who can provide both physical and psychiatric evaluations.

Levels of hypocretin-1 in the cerebrospinal fluid may prove valuable in diagnosing difficult cases of narcolepsy in the future, since hypocretin is often absent in patients with the condition.

Questionnaires

A doctor may administer certain questionnaires on sleeping habits, such as the Stanford Sleepiness Scale or the Epworth Sleepiness Scale.

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Review Date: 07/04/2010
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org)