Mirror Movements in Essential Tremor: Prevalence and Relationship to Mini-Mental Status Test Scores

Figures & Tables

	All ET Cases (N = 148)	ET Cases with MM (N = 115)	ET Cases without MM (N = 33)
Age (years)	84.3 ± 5.5	83.7 ± 5.4a	86.5 ± 5.2
Age (years)	range 74–102	83.7 ± 5.4a	86.5 ± 5.2
Gender (female)	88 (59.5)	69 (60.0)	19 (57.6)
Educational level
<High school	7 (4.7)	5 (4.3)	2 (6.1)
High school diploma	46 (31.1)	38 (33.0)	8 (24.2)
Some college	14 (9.5)	12 (10.4)	2 (6.1)
Bachelors degree or higher	81 (54.7)	60 (52.2)	21 (63.6)
Total tremor score1	24.9 ± 7.3	24.6 ± 7.1	26.1 ± 7.7
Age of tremor onset (years)	42.4 ± 22.9	42.1 ± 22.2	43.2 ± 25.4
Tremor duration (years)	41.8 ± 22.2	41.4 ± 21.9	43.2 ± 23.8
Arm tremor at rest	52 (35.1)	37 (32.2)	15 (45.5)
FMMSE2	26.9 ± 2.7	27.1 ± 2.7b	26.2 ± 2.6
	Median 27.0	Median 28.0	Median 26.0
	Range 11–30	Range 11–30	Range 20–30
	(<24 in 11 (7.4%))	(<24 in 7 (6.1%))	(<24 in 4 (12.1%))
mMMSE3	49.1 ± 5.9	49.5 ± 5.8c	47.7 ± 6.0
	Median 50.0	Median 50.0	Median 49.0
	Range 18–57	Range 18 – 57	Range 35–56
mMMSE executive function score4	9.1 ± 1.9	9.2 ± 1.9d	8.6 ± 2.0
	Median 10.0	Median 10.0	Median 9.0
	Range 3–11	Range 4–11	Range 3–11
MM total score5	9.7 ± 9.6	12.5 ± 9.1	0 ± 0.0
	Median 8.0	Median 10.0	Median 0.0
	Range 0–50	Range 3–50	Range 0–0

Abbreviations: ET, essential tremor; FMMSE, Folstein Mini-Mental State Exam; MM, mirror movements; mMMSE, Modified Mini-Mental Status Examination

Values are either means ± standard deviation or number (percentage).

a p = 0.01 (Student t test) compared to ET cases without MM.

b p = 0.03 (Mann–Whitney test) compared to ET cases without MM.

c p = 0.09 (Mann–Whitney test) compared to ET cases without MM.

d p = 0.10 (Mann–Whitney test) compared to ET cases without MM.

1 Potential range 0–46.

2 Folstein Mini-Mental State Exam (potential range 0–30 (no impairment)).

3 Modified Mini-Mental Status Examination (potential range 0–57 (no impairment)).

4 Potential range 0–11 (no impairment).

5 Potential range 0–80 (maximum).