The Kleine-Levin syndrome: a paramedian thalamic dysfunction?

disturbances such as binge eating, hypersexuality, irritability, and cognitive abnormalities such as feelings of unreality, confusion and hallucinations, of one to two weeks' duration, separated by asymptomatic periods of one to several months' duration. 1 In regard to these clinical features laboratory tests are rather uninfor-mative and etiopathogenesis is still unknown. Routine blood tests are normal. Hormonal levels as well as 24-hour secretory patterns are, with a few exceptions, normal. Plasma and CSF bacterial and viral serologies are normal. A twofold decrease in hypocretin-1 level during the hypersomniac episode as compared to the aymptomatic period has been reported in a single patient. 2 CT scan and MRI are usually normal. The typical EEG pattern is one of general slowing of the background activity frequently associated with bursts of bisynchronous, generalized, moderate to high voltage 5 to 7 Hz waves. 24-hour continuous polysomnography prolonged over 24 hours typically demonstrates prolonged total sleep time, up to 16-18 hours in some reports. The most contributive investigations up to now include: a few neuropathological examinations in favor of localized encephali-tis of viral origin, in different locations however; 3-5 a significant increase of HLA-DQB1*0201 allele frequency; 6 and reports of SPECT studies in single patients documenting hypoperfusion in different parts of the brain, not in the thalami. As for etiopathogenesis an hypothalamic dysfunction has often been suggested mainly based on the combination of clinical features; in a one patient study showing increased values for TSH and PRL, and decreased values for GH and cortisol, an abnormality of hypothalamic dopaminergic tone has been proposed. 11 More recently an autoimmune disorder has been put forward based on the recurrence of episodes, frequent flu-like illness or infection of the upper airway immediately before the onset of the first episode , young age at onset, and data suggesting an association with HLA. 6 The present report of brain imaging SPECT in 5 subjects affected with the Kleine-Levin syndrome, documenting a more than 30% diminished perfusion of both thalami during a symptomatic period in comparison with an asymptomatic period in all cases, plus an hypoperfusion in the basal ganglia and various cortical sites in a majority of cases, can be considered as a breakthrough in the rather uneventful history of the syndrome. Based on previous experience the authors have attempted a comparison between their current findings in Kleine-Levin syndrome patients and previous findings in a 23 and a 28 years …