Endocrinological and Polysomnographic Findings in Kleine-Levin Syndrome: No Evidence for Hypothalamic and Circadian Dysfunction

Five subjects--four men, ages 17-28, and one woman, age 30--with Kleine-Levin syndrome were investigated during symptomatic (SP) and asymptomatic (ASP) periods. Investigations comprised medical history, MRI, polysomnography, 24-hour hormone profile of human growth hormone, melatonin, TSH, cortisol and FSH (in the woman only) assessed every 2 hours, actimetry, and sleep logs. Medical history confirmed presence of the three symptoms diagnostic of of typical Kleine-Levin syndrome: hypersomnia, excessive food intake, and psychic alteration. MRIs of the brain were normal in all patients. Symptomatic periods were triggered by unspecific events, such as infection, sleep deprivation, and alcohol. Polysomnography revealed low sleep efficiency during SPs, decreased amount of slow-wave sleep, and high frequency of stage shifts, indicating sleep fragmentation. Mean 24-hour growth hormone levels were reduced during the SPs in only two patients. Their hGH peaks were dissociated from slow-wave sleep during attacks and intervals, often occurring during wake time. Twenty-four-hour melatonin levels were increased during the SPs in all patients, but were lower in two patients during the nocturnal sleep period. Cortisol, TSH and FSH did not reveal important differences between attacks and intervals. Except for hGH, all hormones had normal circadian excretion during symptomatic and asymptomatic periods. Amplitude of nocturnal activity as assessed by actimetry was significantly increased in two patients, whereas amplitude of daytime activity was significantly reduced in three patients. Actimetry and sleep logs demonstrated prolonged sleep phases during SPs. Our investigation could confirm changes of sleep structure described in the literature. The neuroendocrinological findings could not confirm decreased hGH and cortisol and increased TSH levels during SPs, as previously reported in single cases by many authors. Endocrinological findings did not support an underlying circadian disorder in KLS.