Voxel-based morphometry shows no decreases in cerebellar gray matter volume in essential tremor

Objective: To investigate cerebellar gray matter volume in patients with essential tremor (ET). Methods: We used voxel-based morphometry (VBM) based on high-resolution T1-weighted MRI to compare gray and white matter density between 27 patients with ET and 27 age- and sex-matched healthy control subjects. Fourteen patients had only postural tremor, whereas 13 patients showed additional intention tremor. Results: VBM failed to demonstrate regional decreases in gray and white matter volume in patients with ET. There was, however, an expansion in gray matter depending on the type of tremor. Compared with age- matched control groups, patients with intention tremor showed a relative expansion of gray matter bilaterally in the region of the temporoparietal junction and the right middle occipital cortex. Conclusions: The lack of a consistent decrease in gray and white matter density argues against a progressive neurodegenerative process in essential tremor that leads to a substantial decrease in cerebellar gray matter volume. Patients with predominant intention tremor show a relative expansion of gray matter areas involved in higher order visuospatial processing, which might represent a long-term result of adaptive reorganization compensating the higher demands on the visuospatial control of skilled movements in case of trembling.