Narcolepsy is characterized by sleep attacks that recur throughout the day, and can occur even after a full night of sleep. There are four "accessory symptoms" that many patients with narcolepsy have:
- Cataplexy - a sudden loss of muscle tone with strong emotion, especially with laughter.
- Hypnagogic hallucinations - images and/or sounds at sleep onset, often very realistic in nature.
- Sleep paralysis - inability to move for a few seconds or minutes at sleep onset or upon awakening.
- Disrupted nocturnal sleep.
The cause of narcolepsy is not known. It is thought to be a neurological disorder because: 1) There are animals with narcolepsy. 2) There is a genetic predisposition to narcolepsy. 3) Most patients with narcolepsy have a specific blood antigen. 4) Preliminary research indicates that most patients with narcolepsy have low levels of orexin in their cerebrospinal fluid.
Signs & Symptoms
The symptoms of narcolepsy usually begin at about age 18. Typically, the sleep attacks occur earliest, but some patients may have cataplexy or hypnagogic hallucinations first. In the absence of sleepiness, some patients may be misdiagnosed with epilepsy or psychiatric disorders before the proper diagnosis is made.
The American Academy of Sleep Medicine recommends that the diagnosis of narcolepsy be made with a polysomnogram followed by a Multiple Sleep Latency Test. The polysomnogram allows the sleep physician to rule out other disorders that may cause sleep attacks, such as sleep apnea or periodic limb movement disorder. The Multiple Sleep Latency Test looks for the presence of Rapid Eye Movement (REM) sleep during the day, which is abnormal. The test also quantifies the amount of daytime sleepiness. Abnormal test results, in addition to a clinical history, are used to make the proper diagnosis.
Stimulants are the mainstay of treatment for narcolepsy. These medications prevent sleep attacks and maintain a reasonable level of alertness. Even with optimal treatment, however, many narcoleptic patients require a brief nap one or more times during the day. Some patients require treatment for cataplexy as well. Selective serotonin reuptake inhibitors, such as Prozac, are usually effective treatment for cataplexy.
The NorthShore University HealthSystem Sleep Disorders Program includes the Evanston Hospital Sleep Disorders Center, which is accredited by the American Academy of Sleep Medicine, and the Glenbrook Hospital Sleep Disorders Center. Physicians in the Department of Neurology serve as medical directors of the centers. Staff physicians include additional neurologists and a pulmonologist. All are experienced in the diagnosis and treatment of a broad variety of sleep disorders.
After a clinical evaluation including a detailed history and physical examination, most patients undergo a polysomnogram. Large, private bedrooms are available in both hospital laboratories for the test. State of the art monitoring equipment is used in both centers. Diplomates of the American Board of Sleep Medicine evaluate the polysomnograms. The results are discussed with the patient as well as their referring physician.