Overview
Kleine–Levin syndrome (KLS) was first described in the 1930s, but it has only recently gained attention in pediatrics and child psychiatry. It predominantly affects adolescent boys, though the exact population prevalence is unknown. KLS is characterized by a combination of intense hunger or specific food cravings, an increased need for sleep, and a variety of emotional, behavioral, and neuropsychiatric problems.
Symptoms and Episodes
The symptom constellation of KLS appears abruptly and lasts from a few days to a few weeks. These symptoms then subside, but they can recur after weeks to months, following a similar pattern that often decreases in duration over time. New episodes can occur for one to several years, but relapses generally become less frequent and shorter over time.
Pathophysiology
Hypothalamic dysfunction is suggested as a possible cause of KLS due to:
- The involvement of appetite and sleep symptoms, which implicate hypothalamic systems.
- The syndrome's occurrence primarily during adolescence.
- Its higher prevalence in boys, with the episodic nature potentially being a counterpart to the onset of menarche in girls.
- EEG findings that are sometimes compatible with hypothalamic dysfunction (Arnulf et al., 2015).
Diagnosis
Diagnosis of KLS involves a thorough neuropsychiatric assessment. If the history and symptoms are typical, no further work-up is necessary. However, if there is doubt, neurological and laboratory tests may be essential to exclude other neurological disorders and metabolic problems. A urine and/or blood screen for narcotics and other drugs might also be appropriate. EEGs may show a mild to moderate increase in low-frequency activity and subtle signs of damage to the CSF blood-brain barrier.
Management
Management of KLS often involves assessment and a proper diagnosis. In severe cases affecting school attendance, a trial of stimulants might be indicated. Generally, providing information to the affected child/adolescent, their parents, and teachers is sufficient. Lithium and carbamazepine may be prescribed due to similarities between KLS and certain mood disorders, though responses to treatment are often limited. It is crucial to differentiate KLS from cyclic recurrence of sleepiness during the premenstrual period in adolescent girls, which may be controlled with birth control pills.
Prognosis
The long-term outcome for individuals with KLS is generally good. Despite potential setbacks such as missing a year or two of school, most affected individuals do well by early adulthood. Behavioral problems associated with KLS are highly variable and often linked to somnolence and clouded consciousness.
Differential Diagnosis
Before a correct diagnosis of KLS is established, various psychiatric diagnoses might be considered, including depression, manic depression, schizophrenia, and drug abuse. Encephalitis is commonly suspected during the first episode. The episodic nature of KLS might not be evident until three or more episodes have occurred. Partial or total amnesia for the episodes is also common.
References
Arnulf I (2015) Kleine-Levin Syndrome. Sleep Med Clin 10 (2):151-61. DOI: 10.1016/j.jsmc.2015.02.001 PMID: 26055863.
