Background: Narcolepsy is currently categorized into three groups; narcolepsy with and without emotionally triggered loss of muscle tone (cataplexy), and narcolepsy secondary to other medical conditions. Many patients with hypersomnia are diagnosed too late. The article presents a review of this field.
Material and methods: Sources are literature identified through a non-systematic Pub-Med search and the authors' personal experience with diagnosing and treating patients with narcolepsy and other hypersomnias.
Results: Sleep attacks and emotionally triggered loss of muscle tone are the most important symptoms of narcolepsy with cataplexy. Loss of hypocretin-producing cells is considered to be the cause. Absence of the tissue antigen HLA DQB1*0602 renders narcolepsy an unlikely diagnosis. Narcolepsy without cataplexy occurs less frequently and may have another biological basis. A differential diagnostic evaluation is important to determine whether hypersomnia is associated with obstructive sleep apnea, neurological disease or psychiatric disorders. Polysomnography and multiple sleep latency tests are important diagnostic tools. Hypocretine levels in the cerebrospinal fluid should be measured in most patients. Methylphenidate and other CNS-stimulants are the most potent drugs for treatment of sleep attacks. Tricyclic antidepressive drugs and some newer drugs may be efficient in cataplexy.
Interpretation: Narcolepsy may affect education and work-life. Medication is available. Regular general practitioners should refer patients suspected of having narcolepsy for evaluation in a sleep centre or a hospital with established routines for diagnosis of sleep disorders.