Table 1.
The change in deep brain stimulation effect in long term studies of Essential Tremor.
| Reference, Study type | Patients | Syndrome | Mean follow-up | DBS target | Uni/bilateral stimulation | Off assessment time∧ | Outcome* | Exclusion & other |
|---|---|---|---|---|---|---|---|---|
| Rehncrona et al. (17), prospective |
N = 25 Exclusion = 14 |
ET and PD | ET: 6.5 yrs PD: 6.6 yrs |
VIM | ET: 17/2 PD: 19/0 |
2-year: 4-hours 6–7 years: 1-hour |
ET 2-year delta: 49% 6–7-year delta: 47% Loss of benefit: 4% PD 2-year delta: 77% 6–7-year delta: 54.5% Loss of benefit: 29% |
ET N = 6 (3 dead, 1 refused, 1 lost, 1 battery life end) PD N = 8 (4 dead, 2 refused, 2 lost) |
| Sydow et al. (18), prospective |
N = 19 Exclusion = 7 |
ET | 6.54 yrs | VIM | Baseline: 15/4 6-years: 12/7 |
UN | 1-year delta: 45.6% 6-year delta: 46.3% Gain of benefit: 1% |
N = 7 (1 stopped due to SE, 3 dead, 1 refused, 1 lost, 1 battery life end) |
| Blomstedt et al. (21), prospective |
N = 19 Exclusion = 8 |
ET | 7.17 yrs | VIM | UN | UN | Initial (mean 13 months): delta: 52% Final (86 months) delta: 30% Loss of benefit: 42% |
N = 8 (3 diagnosis revised, 4 died, 1 lost) |
| Favilla et al. (12), retrospective |
N = 28 Controls = 21 Excluded = 41 |
ET | >36 months | VIM | 19/9 | 30 mins | Unilateral 6 months delta: 27% 36 months delta: 26% Loss of benefit: 4% Bilateral 6 months delta: 63% 36 months delta: 37% Loss of benefit: 41% |
N = 41 (10 prior DBS outside facility, 4 stimulator revision, 13 lost, 11 follow-up <24months) |
| Fytagoridis et al. (33), prospective | N = 18 | ET | 4.04 yrs | cZI | 16/2 | DBS deactivated overnight | 1-year delta: 54.5% 3-5-year delta: 51.4% Loss of benefit: 6% |
- |
| Cury et al. (29), retrospective | N = 98 | ET, PD & DT | ET: 8.1 yrs PD: 10.2 yrs DT: 10.8 yrs |
VIM | ET = 35/3 PD = 24/30 DT = 2/4 |
60 mins | PD Bilateral 1-year delta:73% 11–15 year delta: 69% 16–21 years delta: 60% Loss of benefit: 18% Unilateral 1-year delta: 67% 11–16 years delta: 58% 16–21 years delta: 63% Loss of benefit: 6% ET year delta: 66% >10 years delta: 48% Loss of benefit: 27% DT Delta: UN |
DT 4/6 received GPi DBS after VIM DBS, 3 due to lack of efficacy and intolerable side effects |
| Tsubio et al. (32), retrospective | N = 124 Exclusion = 40 | ET & DT | ET: 3.5 yrs DT: 3.4 yrs |
VIM | ET: 72/25 DT: 17/9 |
At least 30 mins | ET 6-month delta: 50% 1–year delta: 42% 2–3 year delta: 37% 4–5 year delta: 38% 6year delta: 34% Loss of benefit: 32% DT 6-month delta: 42% 1–year delta: 45% 2–3 year delta: 41% 4–5 year delta: 8% 6–year delta: 42% No loss or gain of benefit |
N = 40 (24 alternative diagnosis and 16 lack of assessments) |
cZI, caudal zona incerta; DBS, deep brain stimulation; DT, dystonic tremor; ET, essential tremor; GPi, globus pallidus internus; N, number; PD, Parkinson Disease; PSA, posterior subthalamic area; SE, side effect; UN, unknown; VIM, ventralis intermedis nucleus of thalamus.
∧
Time after DBS was switched off.
*
Statistical significance of delta at each time point or change in delta overtime (loss or gain of benefit) were not able to be verified.