Kleine–Levin syndrome

Kleine–Levin syndrome
Synonyms	Familial hibernation syndrome, Sleeping beauty syndrome
Pronounce	N/A
Specialty	N/A
Symptoms	Recurrent episodes of excessive sleep (hypersomnia), cognitive disturbances, altered behavior, increased appetite (hyperphagia), and sometimes hypersexuality
Complications	Risk of impairment in daily functioning during episodes, potential psychological effects from recurrent episodes
Onset	Typically begins in adolescence or early adulthood
Duration	Episodic (episodes can last from several days to weeks, with long periods of remission)
Types	Primary and secondary (due to other underlying conditions)
Causes	The exact cause is unknown; possible genetic and autoimmune factors, hormonal imbalances, or disruptions in the hypothalamus have been suggested
Risks	Family history (suggests a genetic component); more common in males
Diagnosis	Diagnosis is primarily clinical, based on symptom history; no definitive test, but MRI and blood tests may rule out other conditions
Differential diagnosis	Narcolepsy, hypersomnia due to other medical or psychiatric conditions, depression
Prevention	No known prevention methods
Treatment	Symptomatic treatment; pharmacological treatment with stimulants or mood stabilizers may be used during episodes
Medication	Modafinil, methylphenidate, lithium (for mood stabilization)
Prognosis	Most individuals experience a significant improvement or remission with age; some individuals may continue to have occasional episodes
Frequency	Rare; exact prevalence unknown, but estimated to affect 1-2 in every 1,000,000 people
Deaths	Extremely rare; no direct mortality but complications related to prolonged episodes (such as mental health issues) may contribute to risks

Kleine–Levin syndrome (KLS) is a rare sleep disorder characterized by recurrent episodes of excessive sleepiness (hypersomnia) and cognitive or mood changes. Many patients also experience excessive appetite (hyperphagia), increased sexual urges (hypersexuality), and other symptoms. Individual episodes usually last more than a week, sometimes lasting for months. The condition significantly affects the personal, professional, and social lives of sufferers. The severity of symptoms and the course of the syndrome vary between individuals.

Cause

The exact cause of KLS is unknown. The onset of the condition usually follows a viral infection, with several different viruses observed to trigger KLS. The thalamus is thought to possibly play a role, as SPECT has shown thalamic hypoperfusion in patients during episodes. KLS is very rare, occurring at a rate of one in 1 million, which limits research into genetic factors.

Diagnosis

KLS is generally diagnosed after similar conditions have been excluded. MRI, CT scans, lumbar puncture, and toxicology tests are used to rule out other possibilities.

Prevention

There is no known prevention for KLS.

Treatment

There is no known cure for KLS, and there is little evidence supporting drug treatment. Lithium has been reported to have limited effects in case reports, decreasing the length of episodes and duration between them in some patients. Stimulants have been shown to promote wakefulness during episodes, but they do not counteract cognitive symptoms or decrease the duration of episodes.

Prognosis

Patients commonly have about 20 episodes over approximately a decade, with several months generally elapsing between episodes. The condition primarily affects adolescent males, though females can also be affected and the age of onset varies.

Epidemiology

KLS is very rare, with a prevalence of about 1 case per million people. It occurs most frequently among Jews in the US and Israel.

History

The condition is named after Willi Kleine and Max Levin, who described cases of the disease in the early 20th century. It was added to the International Classification of Sleep Disorders in 1990.

In the 2000s, advances in neuroimaging led to the discovery of thalamic hypoperfusion in KLS patients during episodes. This finding indicated a possible role for the thalamus in the development of the syndrome. Genetic research began to gain traction as well, though the rarity of KLS has made progress slow.

The condition gained more visibility in the media in the 2010s, with several documentaries and news reports featuring KLS patients and their experiences. Public awareness has grown, but the syndrome remains rare and research into its causes and potential treatments continues.

External links

• KLS Foundation
• Kleine-Levin Syndrome - An Information Website

kleine_levin at NINDS