Deep Brain Stimulation for Orthostatic Tremor: An Observational Study

Background Primary orthostatic tremor (OT) can affect patients’ life. Treatment of OT with deep brain stimulation (DBS) of the thalamic ventral intermediate nucleus (Vim) is described in a limited number of patients. The Vim and posterior subthalamic area (PSA) can be targeted in a single trajectory, allowing both stimulation of the Vim and/or dentatorubrothalamic tract (DRT). In essential tremor this is currently often used with positive effects. Objective To evaluate the efficacy of Vim/DRT‐DBS in OT‐patients, based on standing time and Quality of Life (QoL), also on the long‐term. Furthermore, to relate stimulation of the Vim and DRT, medial lemniscus (ML) and pyramidal tract (PT) to beneficial clinical and side‐effects. Methods Nine severely affected OT‐patients received bilateral Vim/DRT‐DBS. Primary outcome measure was standing time; secondary measures included self‐reported measures, neurophysiological measures, structural analyses, surgical complications, stimulation‐induced side‐effects, and QoL up to 56 months. Stimulation of volume of tissue activated (VTA) were related to outcome measures. Results Average maximum standing time increased from 41.0 s ± 51.0 s to 109.3 s ± 65.0 s after 18 months, with improvements measured in seven of nine patients. VTA (n = 7) overlapped with the DRT in six patients and with the ML and/or PT in six patients. All patients experienced side‐effects and QoL worsened during the first year after surgery, which improved again during long‐term follow‐up, although remaining below age‐related normal values. Most patients reported a positive effect of DBS. Conclusion Vim/DRT‐DBS improved standing time in patients with severe OT. Observed side‐effects are possibly related to stimulation of the ML and PT.