Probabilistic Refinement of Focused Ultrasound Thalamotomy Targeting for Parkinson's Disease Tremor

Abstract

AbstractBackgroundThere remains high variability in clinical outcomes when the same magnetic resonance image‐guided focused ultrasound (MRgFUS) thalamotomy target is used for both essential tremor (ET) and tremor‐dominant Parkinson's disease (TDPD).ObjectiveOur goal is to refine the MRgFUS thalamotomy target for TDPD versus ET.MethodsWe retrospectively performed voxel‐wise efficacy and structural connectivity mapping using 3‐12‐month post‐procedure hand tremor scores for a multicenter cohort of 32 TDPD patients and a previously published cohort of 79 ET patients, and 24‐hour T1‐weighted post‐MRgFUS brain images. We validated our findings using Unified Parkinson's Disease Rating Scale part III scores for an independent cohort of nine TDPD patients.ResultsThe post‐MRgFUS clinical improvements were 45.9% ± 35.9%, 55.5% ± 36%, and 46.1% ± 18.6% for ET, multicenter TDPD and validation TDPD cohorts, respectively. The TDPD and ET efficacy maps differed significantly (ppermute < 0.05), with peak TDPD improvement (87%) at x = −13.5; y = −15.0; z = 1.5, ~3.5 mm anterior and 3 mm dorsal to the ET target. Discriminative connectivity projections were to the motor and premotor regions in TDPD, and to the motor and somatosensory regions in ET. The disorder‐specific voxel‐wise efficacy map could be used to estimate outcome in TDPD patients with high accuracy (R = 0.8; R2 = 0.64; P < 0.0001). The model was validated using the independent cohort of nine TDPD patients (R = 0.73; R2 = 0.53; P = 0.025—voxel analysis).ConclusionWe demonstrated that the most effective MRgFUS thalamotomy target in TDPD is in the ventral intermediate nucleus/ventralis oralis posterior border region. This finding offers new insights into the thalamic regions instrumental in tremor control, with pivotal implications for improving treatment outcomes. © 2024 The Author(s). Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.