Cerebellar Atrophy in Essential Tremor Using an Automated Segmentation Method

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Fig 1.
Automated labeling of the cerebellum as provided by FreeSurfer. From bottom to top, sections 92, 101, 106, and 110 in the coronal view are shown, respectively. The different structures have unique color codes. After correcting for ICV, MR imaging volumetry using subcortical segmentation reveals cerebellar atrophy in the h-ET group with respect to the controls for absolute gray matter and white matter volumes: mean, respectively: h-ET = 86 ± 7.1 and 23.5 ± 3.3 mm³; a-ET = 89.6 ± 11.1 and 23.9 ± 3 mm³; healthy controls = 91.9 ± 8.2 and 25.7 ± 4.2 mm³.

Table 1:

Demographic and clinical characteristics in ET and control groups*

	h-ET	a-ET	Controls	P Value
Age	70.7 ± 7.8	65 ± 12.8	66.5 ± 7.8	.15^†
Sex (M/F)	6:13	17:10	14:14	.11^‡
Age at onset (yr)	49.96 ± 17.4	45.5 ± 17.9		.41^§
Disease duration (yr)	20.5 ± 15	19.6 ± 15.2		.83^§
Fahn-TRS-A scale	13 (8–16)	9 (2–17)		.004^‖
Brain scale	42 (30–66)	35 (28–65)		.01^‖

Note:—ET indicates essential tremor; h-, head; a-, arm; TRS, Tremor Rating Scale.
* Data are given as mean values (±SD) or median values (range) when appropriate.
† One-way ANOVA, followed by unpaired t test corrected according to Bonferroni.
‡ χ² test.
§ Unpaired test.
‖ Mann-Whitney U test.

Table 2:

Volumes (mean) measured with an automated volumetric method (FreeSurfer)*

	h-ET (n = 19)	a-ET (n = 27)	Controls (n = 28)	PValues
	h-ET (n = 19)	a-ET (n = 27)	Controls (n = 28)	tTest	ANCOVA
ICV	1375.8 ± 119.7	1434.7 ± 127.5	1411.9 ± 122.6	.22
Cortical gray matter	393.8 ± 30.5	413.5 ± 49.5	404.1 ± 32.6	.13	.58
Cortical white matter	358.9 ± 41.1	385.3 ± 57.1	384.6 ± 41.9	.1	.29
Cerebellar gray matter	86 ± 7.1	89.6 ± 11.1	91.9 ± 8.2	.23	.15^†
Cerebellar white matter	23.5 ± 3.3	23.9 ± 3	25.7 ± 4.2	.59	.06^†
Thalamus	11.3 ± 1.2	12 ± 1.5	11.6 ± 1.3	.11	.49
Putamen	9.1 ± 0.9	9.6 ± 1.8	8.9 ± 1.1	.19	.18
Pallidum	2.9 ± 0.3	3 ± 0.5	2.9 ± 0.4	.54	.82
Caudate	6.6 ± 0.7	7.1 ± 1.3	6.5 ± 0.8	.11	.1
Hippocampus	6.8 ± 0.7	7.1 ± 1.1	7 ± 0.8	.31	.76
Lateral ventricle	22.9 ± 14.7	25.9 ± 15.9	21.5 ± 12.8	.51	.55
Third ventricle	1.5 ± 0.7	1.4 ± 0.5	1.4 ± 0.6	.85	.42
Fourth ventricle	1.7 ± 0.6	1.9 ± 0.6	1.7 ± 0.6	.21	.29
Brain stem	18.4 ± 1.9	18.8 ± 2.1	19.3 ± 2.2	.54	.32

Note:—ICV, indicates intracranial volume.
* For each neuroanatomic volume, ANCOVA statistical test covariate with ICV is performed.
† Significant difference after post hoc analysis between h-ET and control groups, performed with the Duncan t test. Volumes are in cubic millimeters.