Age: 17.0
Sex: F
Vaccine: FLUX
Symptoms: Microbiology test normal, Pyrexia, Sleep study, Sleep study normal, Substance use
Clinical narrative: Kleine-Levin Syndrome; Hyperphagia; Changes in behavior including self-gratifying behavior; Hypersomnolence; This literature report (initial receipt 8-Jul-2025) concerns an adolescent female patient with Kleine-Levin Syndrome (KLS). KLS is a rare disease characterized by relapsing-remitting episodes of severe hypersomnolence in association with cognitive, psychiatric, and behavioral disturbances. Described below is a case of KLS associated with viral infection, menstrual cycles, and vaccination.  Patient presented to the pediatric sleep clinic for evaluation of recurrent episodic behavioral changes associated with prolonged sleep time. An initial episode of manipulative behavior associated with family stressors was concerning for underlying depression and she was prescribed escitalopram  but continued to report dissociative' episodes. Approximately six months later, the patient developed a fever associated with acute changes in mentation and increased sleep duration of 18 hours per 24-hour period. The patient underwent evaluation in a pediatric ICU. Workup included MRI brain (negative), respiratory viral panel (positive for human metapneumovirus), urine drug screen (positive for cannabis), and a lumbar puncture with viral testing (normal protein, cell count, and microbiologic testing [note that CSF human metapneumovirus testing was not performed]).  She was diagnosed with encephalopathy due to human metapneumovirus and was discharged home with persistent prolongation of sleep duration for the subsequent 8 days. Over the next 7 months, the patient experienced 3 more episodes of hyperphagia, hypersomnolence, and changes in behavior including self-gratifying behavior lasting for 7-12 days. Two of these episodes were associated with the onset of menstruation. The third episode occurred after influenza vaccination (trade name, manufacturer and lot number not reported - to be requested upon follow up). Note that between episodes, the patient was noted by her mother to return to baseline mentation and have a normalization of sleep duration within a given 24-hour period. Upon evaluation in the pediatric sleep clinic, the patient underwent polysomnography with mean sleep latency testing demonstrating absence of sleep disordered breathing and a mean sleep latency of 8 minutes 24 seconds with no observed sleep onset REM (Rapid Eye Movement) periods. Therapy with modafinil was trialed but she had recurrent episodes. The patient is currently on carbamazepine with an overall reduction in the frequency and duration of episodes.  Authors' comments: Presented above is a rare case of KLS associated with various triggers including viral infection, menstrual cycle, and vaccination.; Reporter's Comments: Causality : Due to the spontaneous nature of the case, the event is considered related for reporting purposes. Related for event Kleine-Levin Syndrome with associated symptoms in line with reporter causality and plausible temporal association (third episode occurred after influenza vaccination). Of note, viral infection with human metapneumovirus, menstruation were triggers for other similar episodes. Adolescent age, family stressors, cannabis intake act as contributing factors which increase the likelihood of developing Kleine-Levin Syndrome.