Kleine–Levin syndrome

Abstract

Kleine–Levin syndrome (KLS) is a rare sleep disorder. Most of the published studies have included only small numbers of patients. Therapeutic and diagnostic studies have the lowest evidence level. This study is a retrospective study including 15 KLS patients of the past 19 years. The patients had first symptoms in their early teens triggered by sleep deprivation, infections, and alcohol intake. Frequency ranged from 2–16/year, duration from 1–6 weeks. Liver enzymes, blood count, inflammatory markers, and magnetic resonance images were normal in all patients. Cerebral spinal fluid (CSF) hypocretin-1 was assessed in 6 patients. It was at the lower normal range in 2 patients and < 130 pg/ml in 2 other patients during an asymptomatic phase, while it was low in 2 patients (96–123 pg/ml) and normal in another patient during a symptomatic phase. Treatment with lithium was established in almost all patients and resulted in marked reduction or cessation of symptomatic episodes. The longest observation was 19 years with a relapse after cessation of lithium. Assessment of CSF hypocretin-1 during and outside of a symptomatic phase is recommended in the diagnostic workup of KLS; however, so far only the clinical course is helpful in establishing the diagnosis. Early treatment is recommended and has been found to be effective in the long course of the disease.