Essential Head Tremor Is Associated with Cerebellar Vermis Atrophy: A Volumetric and Voxel-Based Morphometry MR Imaging Study

Cerebellar Atrophy in Essential Tremor Using an Automated Segmentation Method

“…Our data suggest that automated segmentation, as provided by FreeSurfer, reveals a pattern of atrophy similar to that obtained with VBM and manual tracings. 4 Among all the studied volumes, FreeSurfer showed the presence of atrophy only in the cerebellum and showed this atrophy occurring only in a specific subtype of ET (h-ET). This finding confirms evidence provided by our previous VBM study, 4 in which any significant voxel-by-voxel change (increased or decreased) has been found in the whole brain except for a cluster localized in the anterior vermis, which becomes volumetrically (modulation step) reduced only when comparing patients with h-ET with controls.…”

“…Univariate analysis corrected for ICV revealed no significant volumetric difference in any subcortical areas between ET groups and healthy control subjects (Table 2), though some regions were mostly of borderline statistical significance. Given our previous VBM evidence 4 highlighting the specific cerebellar involvement only in patients with h-ET, we decided to perform an exploratory post hoc analysis to confirm early data. Results revealed the expected reduction of cerebellum including gray matter (P ϭ .02) and white matter volume (P ϭ .01) in patients with h-ET with respect to healthy controls (Fig 1).…”

“…4 From 82 potential subjects (50 patients with a diagnosis of familial ET 11 and 32 healthy controls), 4 patients with ET and 4 healthy controls were excluded owing to MR imaging inaccuracy (see "MR Imaging Scanning and Image Processing"). Forty-six patients with ET (22 women, 48%; mean age, 67.3 Ϯ 11.3 years) and 28 sex-and age-matched healthy controls (14 women, 50%; mean age, 66.5 Ϯ 7.8 years) were enrolled in this study.…”

“…[1][2][3] In a recent voxel-based morphometry (VBM) study, patients within our group with a specific subtype of ET were shown to have cerebellar atrophy primarily involving the anterior vermis. 4 VBM permits an automated voxel-wise whole-brain statistical comparison of MR images by using the statistical parametric mapping (SPM) software (Wellcome Department of Cognitive Neurology, London, UK). However, VBM was not originally designed for the analysis of subcortical structures, and the complicated anatomy of the cerebellum and the surrounding cerebral tissue may hamper the automatic processing of VBM.…”

“…10 The aim of this work was, therefore, to determine the efficacy and utility of using automatic segmentation labeling to quantify atrophy in patients with ET. More precisely, we investigated whether this technique provided results similar to VBM data 4 and whether additional abnormalities in other subcortical regions, beyond the cerebellum might be detected.…”