Characteristics of narcolepsy in preteenaged children.

Narcolepsy is rarely diagnosed in preteenaged children. Its clinical and polysomnographic manifestations, some of which are unusual, are described in four children who were observed prospectively. The mean age at onset of hypersomnia was 10.2 years (range 8.4 to 11.2 years). Daytime naps among these children were lengthy, ranging from 20 to 120 minutes, and generally were considered unrefreshing. Cataplexy was present at the onset in all four children. Three of the four children were obese, with the concurrent nocturnal snoring prompting a misleading concern about obstructive sleep apnea syndrome in two children. The histocompatibility DR2 antigen was present in all four children. Significant behavioral manifestations appeared in all of them. The response to stimulant medications was, at best, modest. Narcolepsy may be difficult to diagnose in this age group. However, a careful history eliciting sleep/wake dysfunction (including cataplexy), leukocyte assays for the histocompatibility DR2 antigen, and serial polysomnographic studies may enable early recognition and treatment of this disease.