title: Diffusion tensor imaging of white matter involvement in essential tremor.
abstract: This study set out to determine whether there is white matter involvement in essential tremor (ET), the most common movement disorder. We collected diffusion MRI and analysed differences in fractional anisotropy (FA) and mean diffusivity (MD) between ET patients and control subjects as markers of white matter integrity. We used both classical ROI-based statistics and whole-brain analysis techniques, including voxel-wise analysis with SPM5 and tract-based spatial statistics (TBSS). Using region of interest (ROI) analysis, we found increased MD bilaterally in the inferior cerebellar peduncles (ICP) and reduced FA in the right-sided ICP of ET patients. Whole-brain analyses with TBSS detected increased MD distributed in both motor and nonmotor white matter fibers of ET patients predominantly in the left parietal white matter, while there were no significant FA differences in these areas between ET patients and controls. Voxel-wise analysis with SPM detected significant increase of MD congruent with the highest probability of difference as detected by TBSS. VBM analysis of T1 images did not detect significant differences in either gray or white matter density between our study groups. In summary, we found evidence for changes in white matter MRI properties in ET. The circumscript pathology of the ICP corroborates the pathogenetic concept of the cerebellum and its projections as key structures for tremor generation in ET. Moreover, increased diffusivity in white matter structures of both hemispheres suggests widespread alterations of fiber integrity in motor and nonmotor networks in ET patients. The underlying cause of the DTI changes observed remains to be elucidated.
authors.affiliation: Department of Neurology, Goethe-University, Frankfurt am Main, Germany. klein@med.uni-frankfurt.de
authors.forename: Johannes C
authors.initials: JC
authors.lastname: Klein
authors.forename: Benedikt
authors.initials: B
authors.lastname: Lorenz
authors.forename: Jun-Suk
authors.initials: JS
authors.lastname: Kang
authors.forename: Simon
authors.initials: S
authors.lastname: Baudrexel
authors.forename: Carola
authors.initials: C
authors.lastname: Seifried
authors.forename: Simone
authors.initials: S
authors.lastname: van de Loo
authors.forename: Helmuth
authors.initials: H
authors.lastname: Steinmetz
authors.forename: Ralph
authors.initials: R
authors.lastname: Deichmann
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Hilker
mesh_terms: D000328:Adult; D000368:Aged; D016880:Anisotropy; D001921:Brain / Q000473:pathology*; D001931:Brain Mapping / Q000379:methods*; D056324:Diffusion Tensor Imaging; D020329:Essential Tremor / Q000473:pathology*; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged