Figure 1
The components of the TPNS system. The TPNS system consists of a stimulator that contains all of the stimulator circuitry, sensors, Bluetooth communication, and battery. Three buttons on the side control power (on/off) and stimulation amplitude. The stimulator connects magnetically to a connector band, which itself fits inside a strap that is used to attach the device around the wrist. A disposable (single-use) electrode band is first wrapped around the wrist, followed by the stimulator/band/strap assembly. The connector band provides electrical connections between the stimulator and electrode band. Several different sizes of electrode and connector bands are available. The stimulator is controlled by a smartphone app via Bluetooth; it sends real-time inertial measurement unit data to the app and receives stimulation settings. When not in use, the stimulator can be charged with the wireless charger.
Table 1
Participant demographics and clinical characteristics.
| CHARACTERISTIC | ALL ENROLLED PARTICIPANTS (n = 25) | PARTICIPANTS WITH EVALUABLE DATA (n = 17) |
|---|---|---|
| Age (years) | 71.0 ± 7.7 [53.0–87.0] | 70.4 ± 8.1 [53.0–87.0] |
| Female | 52 (13) | 47 (8) |
| Race | ||
| White | 92 (23) | 88 (15) |
| Black or African American | 8 (2) | 12 (2) |
| Ethnicity | ||
| Hispanic or Latino | 4 (1) | 6 (1) |
| Non-Hispanic or Latino | 96 (24) | 94 (16) |
| BMI (kg/m2) | 26.1 ± 4.2 [18.4 –37.7] | 26.4 ± 3.5 [20.7–31.5) |
| Family history of ET | 80 (20) | 77 (13) |
| ET onset age (years) | 44.3 ± 19.2 [10.0–78.0] | 44.3 ± 19.2 (19.0–78.0) |
| Prior ET treatment | 72 (18) | 65 (11) |
| On ET medication | 88 (22) | 94 (16) |
| Response to Alcohol | ||
| Yes | 56 (14) | 53 (9) |
| No | 12 (3) | 12 (2) |
| Unsure | 32 (8) | 35 (6) |
| Response to Caffeine | ||
| Yes | 40 (10) | 41 (7) |
| No | 20 (5) | 18 (3) |
| Unsure | 40 (10) | 41 (7) |
| Tremor Severity | ||
| Mild | 32 (8) | 29 (5) |
| Moderate | 60 (15) | 65 (11) |
| Severe | 8 (2) | 6 (1) |
| Stimulation | ||
| Dominant Hand | 72 (18) | 88 (15) |
| Nondominant Hand | 20 (5) | 6 (1) |
| Both Hands | 8 (2) | 6 (1) |
[i] Qualitative data are presented as percentage (number of patients); quantitative data are presented as mean ± standard deviation [range].
Figure 2
Flow diagram of patient progress through the study.
Table 2
Improvement on TETRAS subscales and individual items from baseline to day 7.
| TETRAS SUBSCALE AND ITEM | BASELINE | FOLLOW-UP | CHANGE | p VALUE |
|---|---|---|---|---|
| TETRAS PS Score Dominant Hand (n = 17) a | 14.1 ± 2.2 | 11.4 ± 3.3 | –2.7 ± 2.3 | <0.001 |
| TETRAS PS Score Nondominant Hand (n = 16) b | 9.2 ± 2.8 | 7.8 ± 2.7 | –1.5 ± 1.8 | 0.006 |
| TETRAS ADL Score (n = 15) c | 29.9 ± 4.2 | 20.7 ± 8.7 | –9.3 ± 7.5 | <0.001 |
| TETRAS mADL Score (n = 15) d | 34.8 ± 4.8 | 24.8 ± 9.5 | –10.0 ±7.4 | <0.001 |
| PS Ratings | ||||
| Dominant Hand | ||||
| Forward Outstretched Posture | 2.1 ± 0.5 | 1.7 ± 0.5 | –0.4 ± 0.6 | 0.0112 |
| Lateral “Wing Beating” Posture | 2.4 ± 0.6 | 1.9 ± 0.7 | –0.5 ± 0.6 | 0.0030 |
| Finger-Nose-Finger | 2.0 ± 0.4 | 1.6 ± 0.6 | –0.4 ± 0.5 | 0.0180 |
| Archimedes Spiral Drawing | 2.6 ± 0.5 | 2.3 ± 0.8 | –0.4 ± 0.7 | 0.0479 |
| Handwriting | 2.6 ± 0.9 | 2.0 ± 1.0 | –0.6 ± 0.6 | 0.0022 |
| Dot Approximation | 2.4 ± 0.5 | 1.9 ± 0.5 | –0.5 ± 0.4 | <0.001 |
| Non-Dominant Hand | ||||
| Forward Outstretched Posture | 1.4 ± 0.7 | 1.1 ± 0.7 | –0.3 ± 0.7 | 0.1262 |
| Lateral “Wing Beating” Posture | 1.6 ± 0.8 | 1.3 ± 0.7 | –0.2 ± 0.6 | 0.1347 |
| Finger-Nose-Finger | 1.8 ± 0.7 | 1.4 ± 0.7 | –0.4 ± 0.8 | 0.0754 |
| Archimedes Spiral Drawing | 2.2 ± 0.9 | 2.1 ± 0.9 | –0.2 ± 0.5 | 0.1881 |
| Dot Approximation | 2.2 ± 0.6 | 1.8 ± 0.4 | –0.3 ± 0.4 | 0.0034 |
| ADL Ratings | ||||
| Speaking | 0.9 ± 1.0 | 0.8 ± 1.0 | –0.1 ± 0.7 | 0.7192 |
| Feeding with a spoon | 3.1 ± 0.4 | 2.0 ± 0.9 | –1.1 ± 0.9 | <0.001 |
| Drinking from a glass | 2.9 ± 0.6 | 1.8 ± 1.1 | –1.1 ± 1.1 | 0.0032 |
| Hygiene | 2.5 ± 0.7 | 1.5 ± 1.1 | –0.9 ± 1.1 | 0.0077 |
| Dressing | 1.9 ± 0.8 | 1.3 ± 0.9 | –0.6 ± 0.8 | 0.0140 |
| Pouring | 2.9 ± 0.8 | 2.1 ± 1.0 | –0.8 ± 1.3 | 0.0342 |
| Carrying food trays, plates or similar items | 3.0 ± 0.7 | 2.3 ± 1.1 | –0.7 ± 1.0 | 0.0156 |
| Using keys | 2.5 ± 1.0 | 1.4 ± 1.1 | –1.1 ± 0.9 | <0.001 |
| Writing | 2.7 ± 0.8 | 2.0 ± 1.0 | –0.7 ± 1.0 | 0.0156 |
| Working | 2.5 ± 0.7 | 1.7 ± 0.9 | –0.9 ± 0.9 | 0.0025 |
| Overall disability with the most affected task | 3.1 ± 0.3 | 2.2 ± 0.8 | –0.9 ± 0.8 | <0.001 |
| Social Impact | 2.0 ± 1.0 | 1.6 ± 1.1 | –0.4 ± 0.8 | 0.0824 |
[i] Data are presented as mean ± standard deviation, p values were obtained with paired sample t-tests. TETRAS PS Score for the dominant hand includes TETRAS PS items 4, 6, 7, 8. TETRAS PS Score for the non-dominant hand includes TETRAS PS items 4, 6, 8.
Abbreviations: ADL, activities of daily living; mADL, modified activities of daily living; PS, Performance Scale; TETRAS, The Essential Tremor Rating Assessment Scale.
aMaximum score, 24.
bMaximum score, 20.
cMaximum score, 48.
dMaximum score, 52.