Researchers at Duke University Medical Center, and Veterans Affairs Medical Center, Durham, NC, review the epidemiology, pathophysiology, diagnosis, and treatment of pediatric narcolepsy. Narcolepsy is a disorder of rapid eye movement (REM) sleep characterized by excessive daytime somnolence, associated with sleep paralysis, hypnagogic (when falling asleep) and hypnopompic (when awakening) hallucinations, and cataplexy. Prevalence is 0.05% in the US and Europe; 0.18% in Japan; and 0.002% in Israel; greater in males than females. Onset highest in second decade, with peaks at 14 yrs and 35 yrs. Etiology is unknown, possible neurodegenerative with autoimmune component. Patients with narcolepsy and cataplexy share the same HLA genotype. Predominantly sporadic, sometimes familial, only 25-31% concordance in twin studies. CSF levels of hypocretins less than 110 pg/ml are diagnostic of narcolepsy with cataplexy. Obesity with narcolepsy is associated with low 24 hr leptin levels, a hormone secreted by adipose tissue. Narcolepsy is idiopathic or secondary (symptomatic) and caused by hypothalamic tumors, head trauma, multiple sclerosis, vascular, and encephalitic disorders. In addition to the classic tetrad of narcolepsy symptoms, semi-purposeful, automatic behavior is common during the day, sometimes misdiagnosed as epilepsy, and frequent noctural awakenings. Obesity and obstructive sleep apnea frequently coexist. The interval between symptom-onset to diagnosis is about 10 years. Misdiagnosis is common in children with narcolepsy, leading to delay in treatment. The history combined with polysomnography and mean sleep latency (MSLT) <8 minutes are used in diagnosis in adults and in children older than 8 years. Two or more sleep onset REM sleep periods (SOREMP) in a MSLT within 15 min of sleep onset are consistent with narcolepsy. MRI is normal in idiopathic narcolepsy. Treatment includes lifestyle changes, brief naps, caffeine, reduced carbohydrates or Atkins diet, and pharmacotherapy (methylphenidate, amphetamines, and non-approved pediatric use of modafmil (Provigil), and sodium oxybate (Xyrem). Sodium oxybate is particularly effective in cataplexy in adults. Antidepressants have also been used to treat cataplexy and hypnogogic hallucinations in adults. [1]

COMMENT. A high index of suspicion is required in the diagnosis of narcolepsy. This review provides an excellent account of the diagnosis and treatment of narcolepsy. A sleep specialist reports the highest success rate for correct diagnosis among neurologists (55%), psychiatrists (11%), and pediatricians (0%). [2]

From the Archives: Idiopathic narcolepsy: a disease sui generis. By Adie WI. Brain 1926;49:257-306 and The narcolepsies. By Kinnear Wilson SA. Brain 1928;51:63-109. Adie describes cases seen at Queen Square and misdiagnosed as epilepsy, and summarizes earlier reports by Gelineau (1880). Examples of patients are two soldiers courts-martialed for falling asleep on listening-post duty. Adie coins the term cataplexy associated with narcolepsy. He considers the etiology an endocrine-nervous disorder, a disease sui generis, a proposal dismissed by his senior colleague, Kinnear Wilson, who regards narcolepsy as a syndrome with several different causes, traumatic, endocrine, epileptic, toxi-infective, circulatory, tumor, and idiopathic. Neither Adie nor Kinnear Wilson refers to hyposmia in their account of narcolepsy-cataplexy disorder, but they did locate the pathology in the floor of the third ventricle in symptomatic cases. [3]