[Narcolepsy in a prepubertal boy].

We reported a 10-year-old boy with narcolepsy, the onset of which was at the age of 8 years and 6 months. The initial symptom was excessive daytime sleepiness, followed by cataplexy and disrupted nocturnal sleep. There was neither hallucination nor sleep paralysis. A daytime polysomnogram showed a sleep-onset rapid eye movement period (SOREMP), and human leukocyte antigen (HLA) analysis revealed HLA-DR2/DQB1 * 0602. Treatment with methylphenidate and clomipramine was effective; methylphenidate (30 mg/day) improved his wakefulness and alertness throughout the day, and clomipramine (20 mg/day) reduced the number of cataplexic episodes. Because of their abnormal behavior, prepubertal narcoleptic children may often be misdiagnosed as having epilepsy or an attention deficit hyperactivity disorder. Therefore, they need early diagnosis and treatment. Assistance should be provided to protect them from being labeled as lazy by their parents and school teachers.