Long-term follow-up of task-specific tremor after thalamotomy: a retrospective observational study

Abstract

Objective: This study aimed to report the long-term results of thalamotomy in 23 patients with task-specific tremor. Methods: Data of 23 patients with task-specific tremor who underwent ventralis intermedius nucleus and posterior part of ventro-oral nucleus thalamotomy at the Tokyo Women's Medical University Hospital between 2010 and 2022 were retrospectively analyzed. To evaluate neurological conditions, the severity of task-specific tremor was divided into 0 (no tremor), 1 (slightly tremulous), 2 (moderately tremulous), 3 (accomplishing tasks with great difficulty), and 4 (unable to complete tasks). We also used the subscores “handwriting” (0–4) and “spiral drawing” (0–4) of the Clinical Rating Scales for Tremor. Evaluation scales were presented as medians and interquartile ranges. Results: The severities of task-specific tremor were 3.0 (3.0–4.0) preoperatively and 0.0 (0.0–0.0, p < 0.0001) at the last available evaluation. The writing and spiral drawing of the Clinical Rating Scales for Tremor significantly improved from 3.0 (3.0–4.0) and 3.0 (2.0–3.0) preoperatively, respectively, to 0.0 (0.0–0.0, p < 0.0001) and 0.0 (0.0–0.0, p < 0.0001) at the last available evaluation, respectively. The mean clinical follow-up period was 62.7 ± 26.0 months. Seven (30.4%) patients had focal hand dystonia, which newly developed on the ipsilateral side of the tremor at 2–45 months after the surgery. No serious complications were observed. Interpretation: Thalamotomy significantly improves task-specific tremor with high long-term efficacy, and long-term follow-up is important because focal hand dystonia can develop postoperatively.