New-onset Kleine-Levin syndrome following COVID-19 infection: A case report.

Background: Kleine-Levin syndrome (KLS) is a rare sleep disorder marked by recurrent episodes of severe hypersomnolence with accompanying cognitive, behavioral, or mood disturbances. Infections are frequently reported before symptom onset and have been proposed as potential triggers, although a definitive causal relationship has not been established. Although relapses of KLS after COVID-19 infection have been described, only one possible case of new-onset KLS associated with COVID-19 has been reported, in which a definitive diagnosis was not established.

Case presentation: We describe a 17-year-old male who developed KLS following a confirmed COVID-19 infection. After his clinical recovery, he began experiencing hypersomnolent episodes every few months, each lasting approximately 2 weeks and accompanied by decreased motivation and appetite. As the illness progressed, he developed persistent nausea lasting several weeks before each hypersomnolent episode, suggesting the emergence of a prodromal phase. Treatment with lithium and adjunctive modafinil showed limited efficacy in preventing recurrence or reducing episode severity. Each complete cycle comprising prodromal, hypersomnolent, and recovery phases lasted over a month and significantly disrupted his academic and social functioning.

Conclusion: This case represents the first diagnostically confirmed report of new-onset KLS following COVID-19 infection and suggests a possible autoimmune mechanism triggered by SARS-CoV-2. These findings emphasize the importance of comprehensive clinical assessment beyond objective test results and underscore the urgent need for effective treatment strategies tailored to the heterogeneous and disabling nature of KLS.