Narcolepsy Diagnosis

Submitted by Thiruvelan on Fri, 06/25/2010

Narcolepsy is mostly misdiagnosed or undiagnosed. The most common symptom is the excessive daytime sleepiness, this symptom that is general to many conditions – such as depression, epilepsy and other sleep disorders. Cataplexy – a sudden muscle weakness; is the only unique symptom of narcolepsy?

Diagnosis of Narcolepsy

Diagnosis of narcolepsy can take a very long time that may be more than one year, or even several decades. This is because narcolepsy is very rare condition.

Narcolepsy is sometimes also mistaken for learning problems, seizure disorders, or laziness, especially in school-aged children and teens.

Narcolepsy is diagnosed based on:

  • Signs and symptoms,
  • Medical and family history - infections, brain injuries, exposure to toxins such as pesticides, or autoimmune disorder,
  • Physical exam - infections, thyroid diseases, drug and alcohol abuse, and other medical conditions or sleep disorders also has the same symptoms as narcolepsy,
  • Certain diagnostic tests

Common narcolepsy diagnostic tests are

  • Sleep study
    • Polysomnogram (PSG)
    • Multiple sleep latency test
  • Hypocretin test

Sleep Studies for narcolepsy

Sleep studies are performing at a sleep center; it has two test’s polysomnogram (PSG), and a multiple sleep latency test (MSLT) used to diagnose narcolepsy.

Polysomnogram (PSG) – Need to stay overnight at a sleep center for a PSG. The test records brain activity, eye movements, breathing, heart rate, and blood pressure. This test can help find out:

  • How quickly fall asleep
  • Whether go into rapid eye movement (REM) sleep immediately after falling asleep.
  • Whether wake up frequently during the night

Multiple sleep latency test (MSLT) - a daytime sleep study measures how sleepy during the daytime. It is mostly performing in the next day after a PSG test. During this test, patient should need to be relaxed in a quiet room for about 30 minutes. A technician will record brain activity during this time. The test is repeats three or four times throughout the day.

A MSLT helps to find how quickly one fall asleep during the day (after a full night sleep). It also finds whether one go into REM sleep immediately after falling asleep.

Other tests for narcolepsy

Hypocretin test - measures the levels of hypocretin in the fluid surrounding the spinal cord. Mostly, people with narcolepsy have low levels of hypocretin.

Sample of spinal cord fluid is getting by spinal tap, also called a lumbar puncture. It is performing by the doctor by inserting a needle in the lower back area and then sample of spinal fluid to draw.