Southeast Houston Sleep Medicine

Narcolepsy

The French physician Gélineau first described narcolepsy in 1880
when he wrote about a group of patients who would fall asleep sudden
ly and without warning. In his observations, Gélineau recognized two
broad types of sleep attacks. Some patients fell asleep abruptly at inappropriate times, such as while having a conversation or playing a card game. The second type of attack would occur after an emotional event, such as laughing or becoming excited. These patients would suddenly lose muscle tone, become limp and collapse to the floor in a condition known as cataplexy. Not all patients with narcolepsy experience cataplexy, and modern physicians divide Narcolepsy into two broad categories, Narcolepsy with Cataplexy and Narcolepsy without Cataplexy.

Two other symptoms besides excessive sleepiness and cataplexy make up the “tetrad” of narcolepsy. These are hypnagogic hallucinations and sleep paralysis. Hypnagogic hallucinations are vivid illusions of sounds or visions that happen at the very onset of sleep or at the time of awakening. Patients have described hearing music, seeing nonexistent people or being in imaginary places. Sleep paralysis is an inability to move for several minutes upon awakening. Although it sometimes occurs in healthy young people, it is more common in individuals with narcolepsy.

In order to make the diagnosis of narcolepsy, physicians first exclude other causes of excessive daytime sleepiness. Sleep deprivation is a common cause of daytime sleepiness in our busy modern society. Many Americans do not get the necessary eight hours of sleep each night and become fatigued and sleepy during the day. Similarly, medications or illicit drugs, such as Valium, muscle relaxants, or antihistamines can cause daytime sleepiness.

Once a physician rules out these easily correctable causes of daytime sleepiness, they may consider the diagnosis of Narcolepsy. Making the final diagnosis involves a polysomnography (overnight sleep study) followed by a multiple sleep latency test (nap study). The multiple sleep latency test involves a series of four to five naps that are supervised in a sleep laboratory.

For one to two weeks prior to conducting the multiple sleep latency test, the patient must refrain from taking antihistamines, Valium-like medicines, muscle relaxants, pain relievers, or any other medications causing sedation. On the night before the test, the laboratory will conduct the polysomnography. This monitors the patient for any abnormal sleep, including any evidence of breathing problems.

Two hours after completing the polysomnography, the multiple sleep latency test begins. The laboratory technician will ask the patient to sit in a quiet room. If the patient fails to fall asleep within 20 minutes, that particular nap session will be terminated. If the patient does fall asleep, the technician will continue to observe the patient for evidence of rapid eye movement sleep (REM). This is the category of deep sleep associated with dreaming. Each of the four to five naps is conducted at two-hour intervals. Patients need to refrain from sleeping, drinking coffee, or taking medicines between these naps.

Sleep specialists diagnose narcolepsy based on a specific pattern of sleep during this sequence of naps. In order to meet the laboratory criteria of narcolepsy, the patient must fall asleep during the four to five naps in an average of less than eight minutes. In addition, the patient must experience two sleep-onset REMs. Sleep-onset REM occurs when the patient goes from the wake state to the rapid eye movement or dream state too quickly. Normally, people do not reach the REM stage of sleep for about 70-120 minutes. If the patient reaches the REM state within 15 minutes of falling asleep, this is considered a sleep-onset REM.

The treatment of narcolepsy involves medications. Traditionally, Ritalin was used as a stimulant to help patients with narcolepsy stay awake. Over the past 5-10 years, sleep specialists have moved away from more general stimulants and amphetamines, such as Ritalin and Adderall, because of their addictive potential. Medications that specifically mimic a neurotransmitter called dopamine are now the first line of treatment. These medications, Provigil and Nuvigil, keep patients with narcolepsy awake with fewer side effects than amphetamines.