Kleine-Levin syndrome: a disorder with recurring hypersomnia as main symptom

Kleine-Levin syndrome (KLS) is a rare disorder, characterised by recurring episodes of hypersomnia, as well as behavioural and cognitive changes which may include hyperphagia and hypersexuality. Usually, the symptoms first appear in the teenage years, often following a flu infection. Single episodes last approximately 1–2 weeks and return every 4–6 months. In the median, spontaneous remission occurs after 8 years. Possible causes include an immune reaction in the hypothalamus combined with genetic predisposition. Those most often affected are young men. We report on a 17-year old male with symptoms typical for this condition.

At the age of 16, the patient suffered his first episode of hypersomnia, which lasted 7 days, with an average of 20 hours sleep per day. During such phases, school attendance is not possible. He reported slowed speech and difficulty finding words, as well as problems concentrating and remembering. Intermittently, there was increased appetite and hypersexual behaviour. Between episodes, the patient was unimpaired and performed well academically. Following 6 episodes, the patient came to our hospital. The laboratory parameters (blood count, glucose, lactate, ammonia, thyroid hormone, cortisol, liver function, drug screening), an EEG, an MRI, and a PET-CT were not abnormal. A polysomnography, performed during one hypersomniac episode, showed a reduction in sleeping efficiency and deep sleep phases. At the same time, neuropsychological tests showed an average IQ and below average scores for concentration, learning, and retentiveness. The medical history and test results permitted the diagnosis of KLS.

Conclusion: KLS is a rare disorder that should be considered in the differenzial diagnosis of patients with recurring hypersomnia.