Table 2.
Effect of prolonged phase-specific DBS in essential tremor patients
| Principal movement axis tracked | All trials | ||||||
|---|---|---|---|---|---|---|---|
| Subject | Tremor suppression | Tremor suppression | Tremor severity phase-specific DBS | 50% of the maximum stimulation effect | Average tremor severity high frequency DBS | Average tremor severity in the absence of DBS | Frequency band |
| 1 | 90.06% (n = 4) | 86.94% (n = 7) | IQR 0.06–0.08–0.21 m/s2 | 4.25 s (R = 0.93) | 0.12 m/s2 | 1.9 m/s2 | 3–7 Hz |
| 3 | 78.79% (n = 8) | 76.85% (n = 9) | IQR 0.15–0.21–0.28 m/s2 | 0.62 s (R = 0.69) | 0.08 m/s2 | 4.4 m/s2 | 3–7 Hz |
| 4R | 57.68% (n = 1) | 57.68% (n = 3) | IQR 0.17–0.19–0.33 m/s2 | 3.75 s (R = 0.65) | 0.23 m/s2 | 1.3 m/s2 | 2.5–6.5 Hz |
| 4L | 26.56% (n = 2) | 6% (n = 4) | IQR 0.86–1.35–1.67 m/s2 | 17.5 s (R = 0.14) | 0.09 m/s2 | 2.66 m/s2 | 2.5–6.5 Hz |
| 5 | 65.30% (n = 4) | 52.38% (n = 9) | IQR 0.87–2.02–2.56 m/s2 | 2.12 s (R = 0.46) | 0.03 m/s2 | 5.3 m/s2 | 3.5–6.5 Hz |
Median tremor suppression is indicated across all, and a subset of the trials during which the principal movement axis was the same as the tremor axis being tracked together with the interquartile range (IQR) for tremor severity at the end of phase-specific DBS trials. Median time point when ‘50% of the maximum stimulation effect’ is reached indicates the temporal dynamics of the tremor suppression. The number of trials is indicated by n, while R indicates the median Pearson’s correlation coefficient between the tremor envelope and the sigmoid function fitted.