How Can We Better Leverage the Nocturnal Polysomnogram in the Diagnosis of Childhood-Onset Narcolepsy?

Abstract

Editorial—Kotagal Idiopathic narcolepsy generally has onset during childhood and adolescence, though there may be a delay of several years before a firm diagnosis is established. In the United Kingdom, the time between onset of clinical symptoms and establishment of a definitive diagnosis of narcolepsy was reported to be 10.5 years. 1 Children are not able to accurately express the subjective experiences of cataplexy, hypnagogic hallucinations, or sleep paralysis. This can lead to a delay in diagnosis. In adults, the presence of a sleep-onset REM period on the nocturnal polysomnogram is over 97% specific for the diagnosis of narcolepsy with cataplexy. 2 While the possible utility of the nocturnal sleep onset REM period (nSOREMP) in facilitating the diagnosis of NC in children has been briefly discussed, 3–5 the sensitivity and specificity of the nSOREMP in enabling a diagnosis of child hood narcolepsy-cataplexy has not been evaluated in a large series of subjects. Further, both children with suspected narcolepsy and their parents may find the multiple sleep latency test (MSLT) a stressful experience, which might per se impact sleep onset latency, particularly during the afternoon hours. During the late afternoon, children sometimes become restless, and not emotionally disposed to cooperating for the 4 th or 5 th nap of the MSLT. Further, when it comes to diagnosing narcolepsy, the specificity of the childhood MSLT-derived information is limited—Carskadon et al. found that one or two SOREMPs could be detected in 48% and 16% respectively of otherwise healthy adolescents. 6 Given these limitations of the MSLT in children, are there other, under-evaluated biomarkers within the nocturnal polysomnogram that could aid in the diagnosis of narcolepsy? This clinically relevant question is addressed in this issue by the study of SLEEP by Reiter and colleagues. 7 Reiter et al. conducted a retrospective study of 210 children who had undergone nocturnal polysomnography and MSLT at the Boston Children’s Hospital. After excluding subjects with variables that could confound the test results, they were able to analyze the remaining group of 148 subjects. The cohort was ethnically diverse. Patients were categorized into four groups: narcolepsy with cataplexy (N+C), narcolepsy without cataplexy (N-C), other hypersomnias (H) and “Other.” Subjects with N+C had shorter sleep onset latencies as compared to