Voxel-based morphometry in narcolepsy.
OBJECTIVE
Voxel-based morphometry (VBM) is a magnetic resonance imaging (MRI)-based indirect volumetry, which allows the investigation of the entire brain without restriction of predefined regions-of-interest. Recent studies using this technique reported controversial results in patients with narcolepsy.


METHODS
In this study, 12 patients with narcolepsy according to the criteria of the International Classification of Sleep Disorders were compared to 12 age-matched controls with normal MR images using VBM. Sex and global differences in voxel intensities were used as confounding covariates.


RESULTS
Significant gray matter loss was found in the right prefrontal and frontomesial cortex of patients with narcolepsy. White matter comparison revealed no significant changes in patients or controls. The comparison of cerebrospinal fluid partition detected an enlargement of subarachnoidal space of controls close to the prefrontal cortex.


CONCLUSIONS
The volume reduction of gray matter in narcoleptic patients could indicate a disease-related atrophy pattern. However, the results of VBM studies in narcolepsy are contradictory. A possible systematic bias due to inhomogeneous patient groups, stimulant medication history or pre-statistical image processing must be considered. We suggest that studies with drug-naive patients and/or region-of-interest-based volumetric studies should be performed in areas defined by VBM.
Department of Neurology, Medical University Innsbruck, Anichstr. 35, 6020 Innsbruck, Austria. christian.brenneis@uibk.ac.at
Christian
C
Brenneis
Elisabeth
E
Brandauer
Birgit
B
Frauscher
Michael
M
Schocke
Thomas
T
Trieb
Werner
W
Poewe
Birgit
B
Högl
D000328:Adult; D001284:Atrophy / Q000473:pathology; D001921:Brain / Q000473:pathology*; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009290:Narcolepsy / Q000473:pathology*; D009929:Organ Size