A Voxel-Wise Meta-Analysis of Gray Matter Abnormalities in Essential Tremor

Abstract

Objective: To identify the consistent gray matter (GM) volume changes from the whole brain voxel-based morphometry (VBM) studies on essential tremor (ET).Methods: The whole brain VBM studies comparing ET patients and healthy controls (HCs) were systematically searched in the PubMed, Embase and Web of Science from January 2000 to December 2017. Coordinates with significant differences in regional GM volume between ET patients and HCs were extracted from included studies and the meta-analysis was performed using effect size-based signed differential mapping (ES-SDM).Results: A total of 10 studies with 241 ET patients and 213 HCs were included in the meta-analysis. The consistent GM volume reduction was detected in the left precuneus extending to the left posterior cingulate gyrus. The subgroup meta-analysis which included studies performed on a 3.0 T scanner revealed significant GM volume increases in the bilateral frontal lobes, bilateral temporal lobes, left insula, left striatum and left pons, but obvious publication biases of these findings were detected through funnel plots and Egger's tests.Conclusions: The consistent result of our meta-analysis showed a structural damage in the left precuneus extending to the left posterior cingulate gyrus, which possibly played a role in the cognitive dysfunction and depression in ET patients. It might enhance our understanding of the pathophysiological mechanisms underlying ET.

Neuroimaging and neuropathological findings in essential tremor

“…55 showed different findings, with compensatory increase of the gray matter in the cerebellum and other brain areas, 18,19 rather than atrophy showed by older studies. 55 showed different findings, with compensatory increase of the gray matter in the cerebellum and other brain areas, 18,19 rather than atrophy showed by older studies.…”

“…It could be accepted that studies, where no cerebellar signs or other neurological deficits mentioned, have used only essential tremor patients, but whether their findings could be reliable is still questionable while they had not used the new diagnostic criteria and there is a strong risk of patients with different types of tremor may have been included. Most recent studies using the new classification for tremor and the new diagnostic criteria for essential tremor showed different findings, with compensatory increase of the gray matter in the cerebellum and other brain areas, 18,19 rather than atrophy showed by older studies. [10][11][12][13][14][15] Further studies which will consider the new classification of tremor and will rigorously apply the new diagnostic criteria for essential tremor and which will categorize patient based on both clinical phenotypes and the etiology needed in order to clarify the microscopic and macroscopic changes in essential tremor.…”

“…19 Diffusion-weighted studies reported white matter pathology with an increase in water diffusion or a decrease in preferential direction of diffusion in different cerebellar areas, including the cerebellar peduncles and the dentate nucleus [20][21][22][23] ; however, a smaller number of studies did not reveal any significant cerebellar changes in essential tremor patients. 19 Diffusion-weighted studies reported white matter pathology with an increase in water diffusion or a decrease in preferential direction of diffusion in different cerebellar areas, including the cerebellar peduncles and the dentate nucleus [20][21][22][23] ; however, a smaller number of studies did not reveal any significant cerebellar changes in essential tremor patients.…”

“…A meta-analysis of voxel-based morphometry on the gray matter abnormalities in essential tremor on a total of 10 studies with 241 essential tremor patients and 213 controls found a reduction of the gray matter in the left precuneus, extending to the left posterior cingulate gyrus, and significant volume increases in the bilateral frontal lobes, bilateral temporal lobes, left insula, left striatum, and left pons. 19 Diffusion-weighted studies reported white matter pathology with an increase in water diffusion or a decrease in preferential direction of diffusion in different cerebellar areas, including the cerebellar peduncles and the dentate nucleus [20][21][22][23] ; however, a smaller number of studies did not reveal any significant cerebellar changes in essential tremor patients. 24,25 Magnetic resonance spectroscopy revealed decreased N-acetylaspartate to creatine ratio and N-acetylaspartate to Choline ratio within the cerebellum.…”

Grey matter abnormalities in Parkinson’s disease: a voxel‐wise meta‐analysis

“…Articles were excluded if (1) sufficient information could not be obtained even after contacting the authors; (2) GMV differences were reported only in regions of interest; (3) the article was not peer‐reviewed; (4) there were less than 10 subjects in either the PD or HC group; (5) the studies used overlapping data published in previous VBM studies – in this case, only the study with the largest size group was selected. The quality of each study was evaluated using a 13‐item checklist, which had been used in previous meta‐analyses .…”