Narcolepsy Type 2 in an Adolescent With Childhood Obstructive Sleep Apnea and Coexisting Absence Epilepsy: A Case Report

Narcolepsy is a chronic neurological disorder of sleep-wake regulation whose cardinal features include pathological daytime somnolence and dysregulation of rapid eye movement (REM) sleep. It is frequently underdiagnosed in adolescents owing to symptom overlap with psychiatric, behavioral, and prior sleep disorders, including childhood obstructive sleep apnea (OSA). Narcolepsy type 2 (NT2), defined by excessive daytime sleepiness (EDS) without cataplexy, poses particular diagnostic challenges due to the absence of a single pathognomonic feature. We report an 18-year-old female who presented with a four-year history of persistent EDS, hypnopompic hallucinations, sleep paralysis, and automatic behaviors during microsleeps, including episodes of irrelevant writing during examinations. Subjective daytime somnolence was severe, with an Epworth Sleepiness Scale (ESS) score of 19/24. Past history was notable for childhood OSA managed with adenoidectomy, with residual mild snoring. Physical and neurological examinations were unremarkable. Polysomnography (PSG) demonstrated markedly short sleep latency, multiple sleep-onset REM periods (SOREMPs), and periodic limb movements without apneic episodes or nocturnal desaturation. The Multiple Sleep Latency Test (MSLT) confirmed severe objective hypersomnolence with a mean sleep latency of 1.25 minutes and SOREMPs in three out of four naps. Electroencephalography (EEG) revealed findings consistent with absence seizures, an uncommonly encountered comorbidity in narcolepsy, raising a rare dual diagnosis of NT2 and absence epilepsy. The prior history of childhood OSA and residual snoring initially confounded the clinical picture, underscoring the necessity of objective sleep testing in adolescents with EDS. PSG and MSLT confirmed the diagnosis while excluding insufficient sleep syndrome and untreated OSA. Periodic limb movements observed on PSG may represent a comorbid disorder or an associated feature of narcolepsy. The coexistence of absence epilepsy with NT2 is a rarely reported clinical phenomenon, and its presence in this case further underscores the diagnostic complexity and the critical need for comprehensive neurological evaluation in adolescents presenting with EDS. NT2 in adolescents can be diagnostically challenging due to symptom overlap with prior sleep disorders, psychiatric conditions, and epilepsy. Early recognition, supported by PSG and MSLT, is essential to guide pharmacologic and behavioral interventions, improve daytime function, and reduce psychosocial burden, particularly in rare presentations where narcolepsy coexists with absence epilepsy, demanding heightened clinical vigilance and a broad neurological workup.