Clinical Features of Narcolepsy

Hello friends!!

This is the second one in the four-post series on Narcolepsy. So let's begin.

Narcolepsy is not just a disorder in which the patient sleeps a lot, believe it or not the number of hours in a day spent in sleep by the narcoleptic is no greater than that of a normal individual!!

Narcolepsy is characterized by the classic tetrad of excessive daytime sleepiness, cataplexy, hypnagogic hallucinations and sleep paralysis. There is also a disorder of REM sleep. So let us try to understand these major clinical features.

The essential disorder is one of frequent attacks of irresistible sleepiness several times a day, usually after meals or while sitting in class or in other boring and sedentary situations. Now let us try to picturize the patient.

The eyes close, the muscles relax, breathing deepens slightly and it seems that the individual is dozing. A noise, a touch or even the cessation of lecturer’s voice is enough to awaken the patient. So the periods of sleep rarely last longer than 15min unless the patient is reclining, or if he is in an appropriately comfortable situation to sleep. At the conclusion of the nap, the patient feels somewhat refreshed.

Cataplexy refers to a sudden loss of muscle tone brought on by strong emotion- that is, circumstances in which hearty laughter or, more rarely, excitement, surprise, anger, intense athletic activity. So you can basically “tickle” a Narcoleptic into a Cataplectic state. 

The patient’s head will fall forward, jaw will drop, knees will buckle with sinking to the ground – all with perfect preservation of consciousness (scary, right?). Most attacks of cataplexy are partial, eg., only dropping of the jaw or weakening of the knees.

In about half the patients, there is hypnagogic hallucination and sleep paralysis. Please do not confuse sleep paralysis with cataplexy; sleep paralysis is brief loss of control(not tone) of voluntary muscles that occurs during the period of falling asleep or less often when awakening.

There are two terms which we should know, hypnagogic and hypnopompic. Hypnagogic or predormital refers to the period of falling asleep while hypnopompic or postdormital refers to the period of awakening. Sometimes there may be vivid and terrifying hallucinations with or before the onset of sleep paralysis, which may be visual, auditory, vestibular or somatic, called hypnagogic hallucinations.

That's all. Do go through the other posts in this series.

Role of Orexins in Narcolepsy
Diagnosis of Narcolepsy
Treatment of Narcolepsy

-VM