Table 1.
Characteristics of ET cases
| Characteristic | 348 ET cases in epidemiological study | 9 ET cases in brain repository |
|---|---|---|
| Age in years | 67.5 ± 15.1 (18 – 95) | 87.0 ± 9.2 (90, 68 – 98) |
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| Women | 170 (50.9%) | 5 (55.6%) |
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| Ethnicity | ||
| Non-Hispanic White | 327 (94.0%) | 8 (88.9%) |
| Non-Hispanic African-American | 6 (1.7%) | 1 (11.1%) |
| Hispanic | 10 (2.9%) | 0 (0%) |
| Other | 5 (1.4%) | 0 (0%) |
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| Daily medication for ET | 168 (48.3%) | 8 (88.9%) |
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| Family history of tremor | 213 (61.2%) | 5 (55.6%) |
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| Age of tremor onset in years | 45.0 ± 22.5 (3 – 90) | 55.4 ± 25.4 (60, 14 – 88) |
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| Tremor duration in years | 22.6 ± 18.7 (1 – 81) | 31.6 ± 30.3 (30, 9 – 60) |
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| Total tremor score (range = 0 – 36) | 18.8 ± 7.2 (1 – 36) | Not applicable |
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| Total spiral score (range = 0 – 8) | Not applicable | 4.6 ± 1.2 (4.5, 2.5 – 6) |
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| Rate of tremor progression | 1.97 ± 2.68 (0.03 – 20.00)1 | 0.21 ± 0.20 (0.13, 0.08 – 0.67)3 |
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| Tremor asymmetry index | 3.0 ± 2.7 (0 – 14) 2 | Not applicable |
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| PMI in hours | Not applicable | 5.5 ± 3.1(4.3, 2.9 – 11.5) |
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| Braak stage for Alzheimer’s disease | Not applicable | 1.9 ± 1.4 (2.0, 0 – 4) |
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| CERAD plaque score | Not applicable | 0.2 ± 0.4 (0, 0 – 1) |
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| Torpedoes per section4 | Not applicable | 9.6 ± 6.9 (9.0, 0 –22) |
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| Purkinje cell linear density(cells/mm) | Not applicable | 0.85 ± 0.30 (0.9, 0.44 –1.46) |
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| Degeneration index5 | Not applicable | 14.4 ± 14.3 (9.47, 0.0 – 44.0) |
Mean ± standard deviation (median, minimum - maximum)
In the epidemiological study, rate of tremor progression was defined as the total tremor score (range = 0 – 36) divided by tremor duration in years.
The tremor asymmetry index was defined as the absolute value of the difference between the tremor score on the right (range = 0 – 18) and the tremor score on the left (range = 0 – 18).
In the brain repository, rate of tremor progression was defined as total spiral score (range = 0 – 8) divided by tremor duration in years. Complete spiral data were present in eight of nine ET cases.
Using a standard 20 × 25 mm LH&E-stained cerebellar section that included portions of the cerebellar cortex, white matter, and dentate nucleus, torpedoes in the entire section were counted.
The degeneration index was defined as the number of torpedoes per section divided by the Purkinje cell linear density; high values indicated large numbers of torpedoes and low Purkinje cell linear density (i.e., Purkinje cell loss).