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

BACKGROUND AND PURPOSE: Our aim was to investigate the presence of brain gray matter (GM) abnormalities in patients with different forms of essential tremor (ET). MATERIALS AND METHODS: We used optimized voxel-based morphometry (VBM) and manually traced single region-of-interest analysis in 50 patients with familial ET and in 32 healthy subjects. Thirty patients with ET had tremor of the arms (a-ET), whereas the remaining 20 patients had both arm and head tremor (h-ET). RESULTS: VBM showed marked atrophy of the cerebellar vermis in the patients with h-ET with respect to healthy subjects (Pcorrected .001). Patients with a-ET showed a trend toward a vermal GM volume loss that did not reach a significant difference with respect to healthy controls (Puncorrected .01). The region-of-interest analysis showed a reduction of the cerebellar volume (CV) in the h-ET group (98.2 13.6 mm3) compared with healthy controls (110.5 15.5 mm3, P .012) as well as in the entire vermal area (790.3 94.5 mm2, 898.6 170.6 mm2, P .04 in h-ET and control groups, respectively). CONCLUSIONS: Atrophy of the cerebellar vermis detected in patients with h-ET strongly supports the evidence for the involvement of the cerebellum in the pathophysiology of ET. The lack of a significant CV loss observed in patients with a-ET suggests that a-ET and h-ET might represent distinct subtype