No Additional Benefit of 185 Hz versus 130 Hz at Equivalent Energy in Deep Brain Stimulation for Tremor - A Prospective Clinical Trial

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Background: Deep brain stimulation (DBS) of the ventral intermediate nucleus and posterior subthalamic area (VIM/PSA) in Essential Tremor (ET) and the subthalamic nucleus (STN) in Parkinson's disease (PD) are established treatment for tremor. To achieve maximum tremor control, increasing stimulation frequency beyond 130 Hz is part of clinical practice, but lacks scientific evidence. Objective: To compare tremor suppression under total electrical energy delivered (TEED)-equivalent stimulation at 130 Hz versus 185 Hz in STN-DBS for PD and VIM/PSA-DBS for ET. Methods: In this prospective, double-blind study, acute DBS effects were assessed in 18 people with ET (n = 29 hemispheres), and 25 people with PD (n = 30 hemispheres). Tremor-suppressive effects, evaluated by accelerometry, were compared with TEED-equivalent stimulation at 130 Hz and 185 Hz using linear mixed-effects models, explorative pairwise comparisons, and equivalency testing. Results: Linear mixed-effects models revealed no significant effect of stimulation frequency on tremor improvement in both cohorts. Pairwise comparisons showed no consistent differences in total tremor improvement with TEED-equivalent 185 Hz vs 130 Hz DBS. Post-hoc equivalence testing confirmed equivalence of stimulation frequencies under TEED-equivalent conditions within a +/- 20% margin of relative tremor improvement. Conclusion: This study provides Level II evidence that a higher stimulation frequency of 185 Hz does not offer additional benefit in deep brain stimulation for tremor and supports 130 Hz as the standard stimulation frequency for tremor suppression in ET and PD.