Unravelling Narcolepsy

Objectives: Narcolepsy type 1 (NT1) and narcolepsy type 2 (NT2) are rare, chronic neurologic disorders of hypersomnolence. Narcolepsy type 1 results from the selective loss of orexin-producing neurons, leading to markedly reduced levels of orexin neuropeptides in the brain and CSF. NT2 shares some symptoms with the former but has no orexin deficiency. Both disorders manifest as a spectrum of debilitating symptoms, including excessive daytime sleepiness (EDS), cataplexy (NT1 only), fragmented nocturnal sleep, sleep paralysis, and hallucinations. Diagnosis is particularly challenging, especially in pediatric patients. Methods: We describe 7 pediatric patients presenting with complex narcolepsy phenotype of EDS or cataplexy with a diverse array of comorbid genetic, neurologic, and neuropsychiatric conditions. Results: These cases illustrate the diagnostic challenges in differentiating "primary narcolepsy" from "narcolepsy because of a medical disorder" (e.g., Prader-Willi Syndrome) or "narcolepsy associated with autism spectrum disorder or very early-onset schizophrenia." The patients underwent a comprehensive diagnostic workup, including polysomnography, multiple sleep latency testing (performed after wash-out of concomitant medications), brain magnetic resonance imaging, CSF hypocretin-1 assay, and, in case of consistent clues, autoimmune, and genetic testing. Discussion: Ensuring accurate and prompt narcolepsy diagnosis allows effective and patient-centered management.