Dystonia before and after Unilateral High Intensity Focused Ultrasound Thalamotomy in Essential and Dystonic Tremor

Background Dystonia after focal thalamic lesions including from high‐intensity focused ultrasound (HiFU) ablation have been reported. The risk remains uncertain and is increasingly relevant given the exponential rise in thalamic interventions for tremor over the last decade. Objectives To evaluate the frequency and magnitude of dystonia before and after thalamic HiFU ablation in individuals with essential and dystonic tremor. Method A blinded video‐based analysis was performed using standardized dystonia and tremor rating scales at baseline and two follow‐up intervals. Generalized linear mixed models assessed longitudinal change. Results Thirty individuals met the inclusion/exclusion criteria. Whole body and treated limb dystonia severity did not significantly change over time. One individual developed clinically significant dystonia after treatment yielding an estimated risk of approximately 1–2%. Conclusion Dystonic features were identified in all individuals at baseline, including those diagnosed with essential tremor. Thalamic HiFU ablation was not associated with progression of dystonia severity during follow‐up.