Abstract
BackgroundNo reliable biomarkers are identified in KLS. However, few functional neuroimaging studies suggested hypoactivity in thalamic and hypothalamic regions during symptomatic episodes. Here, we investigated relative changes in regional brain metabolism in Kleine-Levin syndrome (KLS) during symptomatic episodes and asymptomatic periods, as compared to healthy controls.MethodsFour drug-free male patients with typical KLS and 15 healthy controls were included. 18-F-fluorodeoxy glucose positron emission tomography (PET) was obtained in baseline condition in all participants, and during symptomatic episodes in KLS patients. All participants were asked to remain fully awake during the whole PET procedure.ResultsBetween state-comparisons in KLS disclosed higher metabolism in paracentral, precentral, and postcentral areas, supplementary motor area, medial frontal gyrus, thalamus and putamen during symptomatic episodes, and decreased metabolism in occipital and temporal gyri. As compared to healthy control subjects, KLS patients in the asymptomatic phase consistently exhibited significant hypermetabolism in a wide cortical network including frontal and temporal cortices, posterior cingulate and precuneus, with no detected hypometabolism. In symptomatic KLS episodes, hypermetabolism was additionally found in orbital frontal and supplementary motor areas, insula and inferior parietal areas, and right caudate nucleus, and hypometabolism in the middle occipital gyrus and inferior parietal areas.ConclusionOur results demonstrated significant hypermetabolism and few hypometabolism in specific but widespread brain regions in drug-free KLS patients at baseline and during symptomatic episodes, highlighting the behavioral state-dependent nature of changes in regional brain activity in KLS.
Highlights
Kleine-Levin syndrome (KLS) is an extremely rare disease characterized by recurrent episodes of hypersomnia associated with at least one of the following symptoms: cognitive abnormalities, behavioral disturbances, hyperphagia or hypersexuality [1,2,3]
Inconsistencies may stem from the use of different imaging methods, small sample size, imaging at different stages of disease evolution and delay from episode onset, various phenotypes during imaging recording, and medication intake
A statistical trend for hypermetabolism was found within the thalamus and putamen during symptomatic KLS episodes compared to healthy controls, without any changes within these areas between KLS at baseline and controls
Summary
Kleine-Levin syndrome (KLS) is an extremely rare disease characterized by recurrent episodes of hypersomnia associated with at least one of the following symptoms: cognitive abnormalities, behavioral disturbances, hyperphagia or hypersexuality [1,2,3]. No reliable biomarker has been identified yet, and the underlying pathophysiology of KLS remains unknown. Results of the few functional neuroimaging studies conducted in KLS during and between symptomatic episodes are conflicting regarding changes in brain activity, in thalamic, hypothalamic, basal ganglia structures and in frontotemporal areas [6,7,8,9,10,11,12]. To the best of our knowledge no PET-scan imaging studies compared patients with KLS to healthy controls. No reliable biomarkers are identified in KLS. Few functional neuroimaging studies suggested hypoactivity in thalamic and hypothalamic regions during symptomatic episodes. We investigated relative changes in regional brain metabolism in Kleine-Levin syndrome (KLS) during symptomatic episodes and asymptomatic periods, as compared to healthy controls
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