Table 1
Background Characteristics of 22 Patients with Essential Tremor
| Characteristic | Measure |
|---|---|
| Age, in years, mean (range) | 64 (33–78) |
| Sex, no. of females/males | 11F/11M |
| Right-handedness, % (n) | 91 (20) |
| Heredity for tremor, % (n) | 73 (16) |
| Smokers, % (n) | 18 (4) |
| All tobacco use, % (n) | 45 (10) |
| Alcohol consumption in g/week, median (range) | 21 (0–100) |
| Use of β-blockers, % (n) | 36 (8) |
| Duration of treatment with deep brain stimulation in years, mean (range) | 5.9 (2–14) |
Figure 1
A. Postural tremor, dominant hand. B. Kinetic tremor, dominant hand.
Clinical tremor score (0-4) evaluated by the Essential Tremor Rating Scale in 22 patients with essential tremor, treated with deep brain stimulation. Stimulator in the “off” and “on” conditions.
Table 2
Results (scores 0–4) from Assessment of Clinical Tremor in the Dominant Hand Using the Essential Tremor Rating Scale
| OFF (n = 22) | ON (n = 22) | |||||||
|---|---|---|---|---|---|---|---|---|
| Characteristic | Median | Min | Max | Median | Min | Max | Median difference | p-Value1 |
| Rest tremor | 0 | 0 | 2 | 0 | 0 | 1 | 0 | 0.13 |
| Postural tremor | 1 | 0 | 2 | 0 | 0 | 2 | 1 | 0.002 |
| Kinetic tremor | 2 | 0 | 4 | 1 | 0 | 3 | 1.5 | <0.0001 |
| Spiral drawing | 4 | 1 | 4 | 1 | 0 | 4 | 2 | <0.0001 |
| Line drawing | 3 | 0 | 4 | 1 | 0 | 4 | 2 | <0.0001 |
Figure 2
Tremor registrations from one of the essential tremor patients performed with a biaxial accelerometer (CATSYS tremor pen) in the dominant hand.
Measurements in the “off” condition are shown to the left, and in the "on" condition are shown to the right.
Figure 3
A. The CATSYS tremor pen B. The eurythmokinesimeter.
Tremor intensity measured by the CATSYS tremor pen, and Fitts' Law constant measured by a eurythmokinesimeter in the dominant hand, in 22 patents with essential tremor, treated with deep brain stimulation. Stimulator in the “off” and “on” conditions.
Table 3
Results from Measurement of Postural Tremor with the CATSYS System, and Rapid Pointing Movements Using a Eurythmokinesimeter, in the Dominant Hand
| Off (n = 22) | On (n = 22) | |||||||
|---|---|---|---|---|---|---|---|---|
| Characteristic | Median | Min | Max | Median | Min | Max | Median ratio on/off | p-Value1 |
| The CATSYS system | ||||||||
| ↓ Tremor intensity (m/s2) | 2.95 | 0.09 | 25.4 | 0.255 | 0.10 | 18.9 | 0.11 (0.01–1.22) | <0.0001 |
| ↑ Center frequency (Hz) | 4.50 | 3.40 | 6.90 | 4.45 | 3.10 | 7.2 | 0.98 (0.81–1.62) | 0.76 |
| ↑ Frequency dispersion (Hz) | 0.20 | 0.10 | 3.0 | 1.15 | 0.10 | 3.60 | 3.75 (0.20–20.0) | 0.006 |
| ↓ Harmonic index | 0.99 | 0.91 | 0.99 | 0.96 | 0.87 | 0.99 | 0.98 (0.90–1.01) | 0.0004 |
| The eurythmokinesimeter2 | ||||||||
| ↑ Speed (mm/s) | 0.871 | <0.281 | 1.52 | 0.918 | 0.539 | 1.68 | 1.17 (0.75–3.05) | 0.01 |
| ↑ Precision | 0.0758 | 0.0 | 0.540 | 0.115 | 0.0 | 0.660 | 1.22 (0–2.66) | 0.03 |
| ↓ Imprecision | 0.970 | 0.527 | 1.0 | 0.908 | 0.368 | 1.0 | 0.93 (0.70–1.07) | 0.001 |
| ↓ Unsureness | 1.35 | 1.0 | >2.22 | 1.19 | 1.02 | 2.55 | 0.91 (0.54–1.27) | 0.08 |
| ↓ Tremor | 0.367 | 0.0875 | >0.857 | 0.278 | 0.0480 | 1.07 | 0.69 (0.11–2.44) | 0.17 |
| ↓ Transit duration | 1.05 | 0.581 | >3.80 | 0.991 | 0.538 | 1.61 | 0.82 (0.26–1.29) | 0.0002 |
| ↓ Contact duration | 0.0870 | 0.0308 | >0.222 | 0.147 | 0.0563 | 0.486 | 1.57 (0.34–4.11) | 0.0008 |
| ↓ Fitts’ Law constant | 0.241 | 0.134 | >0.929 | 0.185 | 0.112 | 0.308 | 0.77 (0.27–1.30) | <.0001 |
| ↓ Irregularity | 0.232 | 0.0630 | >1.75 | 0.130 | 0.0460 | 0.454 | 0.63 (0.08–2.13) | <0.0001 |