Diagnosing And Treating Narcolepsy
Narcolepsy is a condition that affects 1 in 2,000 individuals in the United States with equal
male to female preponderance. The peak of incidence is in the teens and twenties. Classic
symptoms include excessive daytime sleepiness; cataplexy defined as sudden brief episodes
of muscle weakness; sleep paralysis; and hypnagogic hallucinations (vivid visual, auditory,
tactile and kinetic sensations).
Other associated disorders frequently accompanying
narcolepsy include fragmented sleep, obstructive sleep apnea, periodic leg movements,
REM behavioral disorder, and other parasomnias. The most common presenting symptom
is sleepiness during the day. This sleepiness may vary from mild to severe, may vary over
the course of the day, and is most apparent when a narcoleptic is sedentary or bored.
True “sleep attacks” with sudden complete loss of muscle tone are very rare. Of interest
and great concern is the presence of “automatic” behaviors. Narcoleptic patients may
be still functional enough during the attack to continue driving or working with heavy
When health professionals think of narcolepsy, its hallmark feature called
cataplexy comes to mind. Cataplexy is defined as muscle weakness triggered by strong
emotions (e.g., laughter, joking, anger). At times it may be so mild as to present in the form
of slurred speech in a narcoleptic patient telling an animated story. What is the underlying
cause of narcolepsy? It is the loss of Hypocretin (Orexin) secreting neurons in the
hypothalamus. This neurotransmitter maintains the state of wakefulness and suppresses
REM sleep. Even though there is a genetic linkage to this process, only 1/3 of monozygotic
twins both develop narcolepsy.
The risk of a parent with narcolepsy to have an affected child is about 1%. Most of
narcolepsy is primary. However, secondary narcolepsy may occur in patients with
lesions involving the posterior and lateral hypothalamus or mid-brain (tumors, strokes,
demyelination or inflammation).
Diagnosis of narcolepsy in a sleepy patient with an
otherwise normal overnight polysomnogram is made by MSLT (multiple sleep latency
test) that immediately follows an overnight study. It is a morning and day study that
consists of 5 observed naps spaced 2 hours apart. Short sleep onset of <8 minutes along
with occurrence of 2 episodes of sleep onset REM are diagnostic of narcolepsy. The
treatment of narcolepsy may be divided into behavioral modifications and pharmacologic
Programmed 15-20 minute “power” naps during the day and avoidance of
sedentary jobs will help maintain vigilance. Medication therapy includes amphetamines
(most commonly used Methylphenidate packaged as Ritalin or Concerta) or newer agents
Modafinil (Provigil), Armodafinil (Nuvigil), Xyrem (Sodium Oxybate). Certain other
agents have shown promise as adjunct therapies specific for cataplexy. Those include
Venlafexine (Effexor), Fluoxetine (Prozac), and Clomipramine (Anafranil). Even though it is
relatively infrequent as compared to other causes of sleepiness, narcolepsy should be in the
differential of sleepiness in an otherwise young and healthy individual.
Call us at 612-339-2836 or toll-free at 866-316-0769 to refer your patient for an appointment, or submit an online referral.