Kleine–Levin Syndrome (KLS)

Primer

Kleine–Levin Syndrome (KLS) is a rare neuropsychiatric disorder characterized by persistent episodic hypersomnia, hyperphagia, cognitive impairment, and mood changes. Individuals can also experience hypersexuality, personality changes, and behavioural changes.

Epidemiology
  • The prevalence of KLS is thought to be extremely rare, perhaps 1 in 1 million.
Prognosis
Comorbidity
Risk Factors
  • Adolescent males are at the greatest risk, and is much more common in males than females.

Diagnostic Criteria

Signs and Symptoms

  • Individuals typically present with recurrent episodes of hypersomnia, sleeping up to 18 hours per day.
    • These episodes can last between days to weeks, and can occur between one to ten times per year.
    • During these episodes, individuals typically also have hyperphagia and hypersexuality.
    • Confusion, irritability, aggression, and hallucinations can also occur during these episodes.
  • In between these episodes, individuals with have normal sleep and behaviours
  • The average duration of these episodes is about 4 years.

Pathophysiology

Differential Diagnosis

Investigations

Physical Exam

  • Episodic upward (vertical) gaze palsy is an uncommon finding in KLS.[1]

Treatment

Guidelines

Resources

For Patients
For Providers
Articles
Research

References

1) Lv, H., Long, X., Lv, Y., & Zhou, J. (2024). Acute encephalitis induced Kleine-Levin syndrome with episodic vertical gaze dysfunction during hypersomnia episodes. Journal of Clinical Sleep Medicine, jcsm-11242.
2) Itokawa, K., Fukui, M., Ninomiya, M., Yamamoto, T., Imabayashi, E., Tamura, N., ... & Araki, N. (2009). Gabapentin for Kleine-Levin syndrome. Internal Medicine, 48(13), 1183-1185.