627Childhood Narcolepsy/Hypersomnia-Han et al on the pediatric population could help address issues related to puberty, genetic predisposition, and environmental triggers, and possibly shed light on factors that might delay diagnosis. We report on findings from a pediatric cohort of patients who presented with primary hypersomnia to a sleep clinic in Beijing, China over a period of ~10 years. All were evaluated in a standard fashion and classified as narcolepsy with or without cataplexy or idiopathic hypersomnia. Our purpose was to describe age of onset and clinical features of primary hypersomnia among a mainland Chinese cohort of children, and to compare the findings to the literature.
METHODS
PatientsPatients were children, defined as < 18 years of age, successively presenting with hypersomnia seen over a period of ~10 years (September, 1998 to May, 2009) at People's Hospital, Beijing University, Beijing. A total of 417 children (63%) were drawn from a population of 671 adults and children with hypersomnia. The hospital has a pulmonary medicine departmentbased sleep center, which sees both children and adults, and receives referrals from all of mainland China. It is estimated that 70% of the diagnosed narcolepsy patients in mainland China are seen at this center at People's Hospitals.12 A prior report focused on the impact of a narcolepsy recognition strategy in a pediatric neurology clinic, 13 whereas this report retrospectively describes a cohort with a broader symptom profile, evaluated using a stan-
INTRODUCTIONNarcolepsy-cataplexy (NC) occurs worldwide. In China, there is a population prevalence of 0.034% in patients in South China presenting to sleep centers in Hong Kong 1,2 and a prevalence of 0.014% in Korean adolescents with similar clinical and biological presentations.3-5 Studies in North America and Europe estimates are similar. As the origin and mechanisms that produce narcolepsy are not well understood, comparisons of clinical presentations in collections of several characterized patient groups can inform future studies of clinical and genetic epidemiology.Narcolepsy-cataplexy is said to present in the second to third decade of life, with 70% to 80% of patients reporting onset between 10-20 years of age. Large sample size observations from the United States, Canada, Europe, and Japan report that half of adult patients with narcolepsy report narcolepsy onset prior to 15 years old, and only exceptionally at 5 or younger.6-9 Studies in the 1980s-1990s reported a median delay > 10 years between onset and diagnosis, 10 whereas a more recent report suggests the delay can be only a few years, particularly in children.11 A focus Objective: To retrospectively describe childhood presentations of primary hypersomnia with an emphasis on narcolepsy-cataplexy in a Chinese population. Methods: A total of 417 children (< 18 years old) successively presenting with complaints of hypersomnia without anatomic cause or sleep apnea risk were evaluated using the Stanford Sleep Inventory, human leukocyte antigen (HLA) ...