Table 1
Demographic and historical features.
| OVERALL | ET | ET PLUS | ET-PD | P (ALL) | ADJ. P (ET VS ET PLUS) | ADJ. P (ET VS ET-PD) | ADJ. P (ET PLUS VS ET-PD) | |
|---|---|---|---|---|---|---|---|---|
| Tremor Classification | ||||||||
| Number of patients (%) | 300 (100%) | 62 (20.7%) | 160 (53.3%) | 78 (26.0%) | ||||
| Gender | ||||||||
| Male | 157 (52.3%) | 36 (58.1%) | 70 (43.8%) | 51 (65.4%) | 0.0044 | 0.055 | 0.38 | 0.0017 |
| Female | 143 (47.7%) | 26 (41.9%) | 90 (56.3%) | 27 (34.5%) | ||||
| Age, years | ||||||||
| Mean age (SD) | 66.1 (13.6) | 60.5 (15.7) | 68.1 (13.6) | 66.3 (10.2) | 0.00095 | 0.00056 | 0.1679 | 0.0215 |
| Median age | 67.0 | 65.5 | 70 | 65 | ||||
| Age at Tremor Onset, years | ||||||||
| Mean age at onset (SD) | 38.3 (21.0) | 34.3 (19.0) | 40.5 (22.0) | 36.9 (19.9) | 0.13 | 0.053 | 0.38 | 0.29 |
| Median age at onset | 41 | 33 | 45 | |||||
| Tremor duration, years | ||||||||
| Mean duration (SD) | 28.1 (18.8) | 26.0 (18.2) | 28.1 (19.1) | 29.6 (18.9) | 0.59 | 0.47 | 0.29 | 0.67 |
| Median duration | 23 | 22 | 22 | 25 | ||||
| Family History | ||||||||
| Tremor | 215 (71.7%) | 40 (64.5%) | 123 (76.9%) | 52 (66.7%) | 0.097 | 0.061 | 0.79 | 0.94 |
| PD | 58 (19.3%) | 16 (25.8%) | 23 (14.4%) | 19 (24.4%) | 0.066 | 0.045 | 0.84 | 0.058 |
| Dystonia | 8 (2.7%) | 2 (3.2%) | 6 (3.8%) | 0 (0.0%) | 0.2675 | 1 | 0.1943 | 0.1814 |
| Clinical Features by History | ||||||||
| Balance disturbance | 82 (27.3%) | 10 (16.1%) | 44 (27.5%) | 28 (35.9%) | 0.033 | 0.076 | 0.009 | 0.19 |
| Depression | 89 (29.7%) | 16 (25.8%) | 49 (30.6%) | 24 (30.8%) | 0.76 | 0.48 | 0.52 | 0.98 |
| Anxiety | 61 (20.3%) | 5 (8.1%) | 32 (20.0%) | 24 (30.8%) | 0.004 | 0.03 | 0.001 | 0.066 |
| RBD symptoms | 17 (5.7%) | 1 (1.6%) | 4 (2.5%) | 12 (15.4%) | 0.0003 | 1 | 0.005 | 0.0002 |
[i] Adj. p = adjusted p (statistically significant cutoff of p < 0.017 by Bonferroni correction). SD = standard deviation, PD = Parkinson’s disease, RBD = rapid-eye movement behavior disorder, ET = essential tremor, ET plus = essential tremor plus, ET-PD = essential tremor-Parkinson’s disease.
Figure 1
Age at Onset of Tremor Histogram. A bimodal distribution is visible in the 2nd and 6th decades of life.
Table 2
Examination features.
| OVERALL | ET | ET PLUS | ET-PD | P (ALL) | ADJ. P (ET VS ET PLUS) | ADJ. P (ET VS ET-PD) | ADJ. P (ET PLUS VS ET-PD) | |
|---|---|---|---|---|---|---|---|---|
| Examination features | ||||||||
| Rest tremor | 130 (43.3%) | n/a | 64 (40.0%) | 66 (84.6%) | n/a | n/a | n/a | <0.0001 |
| Postural tremor | 294 (98.0%) | 62 (100.0%) | 157 (98.1%) | 75 (96.2%) | 0.35 | 0.56 | 0.25 | 0.40 |
| Kinetic tremor | 290 (96.7%) | 62 (100.0%) | 156 (97.5%) | 72 (92.3%) | 0.033 | 0.578 | 0.034 | 0.084 |
| Isometric tremor | 90 (30.0%) | 25 (40.3%) | 46 (28.8%) | 19 (24.4%) | 0.11 | 0.097 | 0.043 | 0.48 |
| Body areas involved | ||||||||
| Head | 141 (47.0%) | 20 (32.3%) | 95 (59.4%) | 26 (33.3%) | <0.0001 | 0.00029 | 0.89 | 0.00016 |
| Voice | 74 (24.7%) | 15 (24.2%) | 51 (31.9%) | 8 (10.3%) | 0.0014 | 0.26 | 0.027 | 0.00029 |
| Tongue | 41 (13.7%) | 7 (11.3%) | 27 (16.9%) | 7 (9.0%) | 0.21 | 0.30 | 0.65 | 0.10 |
| Upper limbs | 300 (100.0%) | 62 (100.0%) | 160 (100.0%) | 78 (100.0%) | n/a | n/a | n/a | n/a |
| Lower limbs | 70 (23.3%) | 13 (21.0%) | 43 (26.9%) | 22 (28.2%) | 0.91 | 0.97 | 0.71 | 0.68 |
| Trunk | 51 (17.0%) | 11 (17.7%) | 28 (17.5%) | 12 (15.4%) | 0.91 | 0.97 | 0.71 | 0.68 |
| Associated features | ||||||||
| Parkinsonism | 117 (39.0%) | n/a | 39 (24.4%) | 78 (100.0%) | n/a | n/a | n/a | <0.0001 |
| Dystonia | 75 (25.0%) | n/a | 68 (42.5%) | 7 (9.0%) | n/a | n/a | n/a | <0.0001 |
| Tandem gait abnormality | 69 (23.0%) | n/a | 62 (38.8%) | 7 (9.0%) | n/a | n/a | n/a | <0.0001 |
| Ataxia | 8 (2.7%) | n/a | 6 (3.8%) | 2 (2.6%) | n/a | n/a | n/a | 0.63 |
| Cognitive impairment | 45 (15.0%) | n/a | 26 (16.3%) | 19 (24.4%) | n/a | n/a | n/a | 0.134 |
| Neuropathy | 35 (11.7%) | 3 (4.8%) | 24 (15.0%) | 8 (10.3%) | 0.10 | 0.038 | 0.35 | 0.31 |
| TETRAS evaluations | ||||||||
| # patients | 88 (29.3%) | |||||||
| Mean performance subscore (SD) | 23.4 (6.75) | 19.7 (5.2) | 24.7 (6.5) | 21.8 (7.9) | 0.015 | 0.0047 | 0.39 | 0.15 |
| Mean ADL subscore (SD) | 21.2 (10.24) | 17.9 (8.4) | 24.0 (9.9) | 12.9 (8.4) | 0.00036 | 0.022 | 0.088 | 0.00037 |
| Average total score (SD) | 44.8 (15.47) | 37.8 (12.6) | 49.4 (15.0) | 33.6 (12.0) | 0.00022 | 0.00062 | 0.36 | 0.0005 |
[i] Adj. p = adjusted p (statistically significant cutoff of p < 0.017 by Bonferroni correction). SD = standard deviation, ET = essential tremor, ET plus = essential tremor plus, ET-PD = essential tremor-Parkinson’s disease. TETRAS = The Essential Tremor Rating Assessment Scale, ADL = activities of daily living. Cognitive Impairment included MCI or dementia by neuropsychological testing, or MoCA score of ≤ 25. Some TETRAS scores had only ADL or performance subscores available, and were not included in the total score average.
Table 3
Treatment history.
| OVERALL | ET | ET PLUS | ET-PD | P (ALL) | ADJ. P (ET VS ET PLUS) | ADJ. P (ET VS ET-PD) | ADJ. P (ET PLUS VS ET-PD) | |
|---|---|---|---|---|---|---|---|---|
| Medication History | ||||||||
| Average # of current oral medications (SD) | 1.92 (1.2) | 1.4 (1.0) | 1.8 (1.1) | 2.5 (1.3) | <0.0001 | 0.013 | <0.0001 | 0.00046 |
| Median # of current oral medications | 2 | 1 | 2 | 2 | ||||
| Average # of prior oral medications (SD) | 3.81 (1.9) | 3.1 (1.5) | 3.6 (1.8) | 4.7 (2.0) | <0.0001 | 0.058 | <0.0001 | <0.0001 |
| Median # of prior oral medications | 4 | 3 | 4 | 5 | ||||
| At least partially responsive | 213 (71.0%) | 43 (69.4%) | 105 (65.5%) | 65 (83.3%) | 0.018 | 0.60 | 0.050 | 0.005 |
| Improved tremor with alcohol | 79 (26.3%) | 16 (25.8%) | 44 (27.5%) | 19 (24.4%) | 0.87 | 0.80 | 0.84 | 0.61 |
| BoNT Injections | ||||||||
| Received BoNT injections | 123 (41.0%) | 26 (41.9%) | 81 (50.6%) | 16 (20.5%) | <0.0001 | 0.25 | 0.006 | <0.0001 |
| BoNT effective | 91/123 (74.0%) | 21 (80.8%) | 59 (72.8%) | 11 (68.8%) | 0.64 | 0.42 | 0.46 | 0.76 |
| DBS | ||||||||
| Underwent DBS placement | 38 (12.7%) | 11 (17.7%) | 17 (10.6%) | 10 (12.8%) | 0.36 | 0.15 | 0.42 | 0.62 |
| DBS effective | 35/38 (92.1%) | 11 (100.0%) | 15 (88.2%) | 9 (90.0%) | 0.601 | 0.51 | 0.48 | 1 |
[i] Adj. p = adjusted p (statistically significant cutoff of p < 0.017 by Bonferroni correction). ET = essential tremor, ET plus = essential tremor plus, ET-PD = essential tremor-Parkinson’s disease, SD = standard deviation, BoNT = botulinum toxin, DBS = deep brain stimulation.