title: DTI reveals hypothalamic and brainstem white matter lesions in patients with idiopathic narcolepsy.
abstract: BACKGROUND
  Symptomatic narcolepsy is often related to hypothalamic, pontine, or mesencephalic lesions. Despite evidence of disturbances of the hypothalamic hypocretin system in patients with idiopathic narcolepsy, neuroimaging in patients with idiopathic narcolepsy revealed conflicting results and there is limited data on possible structural brain changes that might be associated with this disorder.
  
  
  METHODS
  We investigated with diffusion tensor imaging (DTI) whether microstructural abnormalities in the brain of eight patients with idiopathic narcolepsy with cataplexy are detectable compared to 12 healthy controls using a 1.5T MRI scanner. Whole-head DTI scans were analyzed without an a priori hypothesis. Voxelwise statistical analysis of fractional anisotropy (FA) data was performed using Tract-Based Spatial Statistics (TBSS), a non-linear analysis approach.
  
  
  RESULTS
  Patients with narcolepsy showed microstructural white matter changes in the right hypothalamus as well as in the left mesencephalon, pons, and medulla oblongata. Additionally, areas in the left temporal lobe, the pre- and postcentral gyrus, the frontal and parietal white matter, the corona radiata, the right internal capsule, and the caudate nucleus had altered microstructure in patients with narcolepsy.
  
  
  CONCLUSIONS
  Our study shows widespread microstructural white matter changes that are not visible on conventional MRI scans in patients with idiopathic narcolepsy. In support of the evidence from patients with symptomatic narcolepsy, we found microstructural changes in the hypothalamus, mesencephalon, pons, and medulla oblongata. Changes are in accordance with disturbances of the hypothalamic hypocretin system and its projections to mesencephalic and pontine areas regulating REM sleep.
authors.affiliation: Philipps-University Marburg, Department of Neurology, Marburg, Germany.
authors.forename: K
authors.initials: K
authors.lastname: Menzler
authors.forename: M
authors.initials: M
authors.lastname: Belke
authors.forename: M M
authors.initials: MM
authors.lastname: Unger
authors.forename: T
authors.initials: T
authors.lastname: Ohletz
authors.forename: B
authors.initials: B
authors.lastname: Keil
authors.forename: J T
authors.initials: JT
authors.lastname: Heverhagen
authors.forename: F
authors.initials: F
authors.lastname: Rosenow
authors.forename: G
authors.initials: G
authors.lastname: Mayer
authors.forename: W H
authors.initials: WH
authors.lastname: Oertel
authors.forename: J C
authors.initials: JC
authors.lastname: Möller
authors.forename: S
authors.initials: S
authors.lastname: Knake
mesh_terms: D000328:Adult; D001933:Brain Stem / Q000473:pathology*; D038524:Diffusion Magnetic Resonance Imaging; D005260:Female; D006801:Humans; D007031:Hypothalamus / Q000473:pathology*; D056784:Leukoencephalopathies / Q000473:pathology*; D008297:Male; D008526:Medulla Oblongata / Q000473:pathology; D008636:Mesencephalon / Q000473:pathology; D008875:Middle Aged; D009290:Narcolepsy / Q000473:pathology*; D009413:Nerve Fibers, Myelinated / Q000473:pathology; D011149:Pons / Q000473:pathology; D013702:Temporal Lobe / Q000473:pathology