Comparative Study of Focused Ultrasound Unilateral Thalamotomy and Subthalamotomy for Medication‐Refractory Parkinson's Disease Tremor

Abstract

BackgroundUnilateral focused ultrasound ventral intermediate thalamotomy (Vim‐FUS) is effective in treating Parkinson's disease (PD) tremor. Ultrasound ablation of the subthalamic nucleus (STN‐FUS) has demonstrated efficacy in improving all cardinal motor features of PD, including tremor.ObjectiveTo compare the efficacy in parkinsonian tremor control between Vim‐FUS and STN‐FUS.MethodsRetrospective, two‐center study including consecutive PD patients with medication‐refractory tremor who underwent unilateral Vim‐FUS or STN‐FUS between June 2015 and August 2022. Patients scored ≥2 for postural and/or resting tremor on the most affected body side in the off‐medication state. The primary outcome was the between‐group difference in tremor improvement on the treated side at 12‐month follow‐up, including a responder's analysis. Data regarding safety, global motor status, and dopaminergic requirements were also collected. Group comparisons used repeated measures ANOVA with Bonferroni correction; statistical significance for P < 0.05.ResultsAmong 175 patients treated at the two sites, 63 were included (23 Vim‐FUS, 40 STN‐FUS). At baseline, both groups were equivalent in disease duration (6.7 ± 3.8 vs. 6.1 ± 3.4 years, P = 0.48) and tremor severity (5.7 ± 1.5 vs. 5.9 ± 2.5, P = 0.7). While the benefit in tremor was equivalent between the groups at 4 months (P = 0.15), tremor reduction was greater in STN‐ FUS patients at 12 months (4.4 ± 2.0, 95% CI 3.7–5.0 compared with 2.7 ± 3.7, 95% CI 1.1–4.3 for Vim‐FUS, P = 0.012). In 47.5% (19/40) of STN‐FUS patients tremor was completely abolished versus 8.7% (2/23) in Vim‐FUS patients (P < 0.01). Most adverse events were mild (91%) and resolved by 12 months.ConclusionsSTN‐FUS and Vim‐FUS significantly improved medication‐refractory PD tremor; however, subthalamotomy might have greater and more sustained effect. © 2025 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.