Noninvasive Thalamotomy for Refractory Tremor by Frameless Radiosurgery.

Abstract

OBJECTIVE\nWe sought to determine whether a more widely accessible, non-invasive frameless approach to radiosurgical thalamotomy would improve objective measures of refractory essential or parkinsonian tremor without added toxicity compared to reports of frame-based radiosurgery.\n\n\nMETHODS\nWe conducted a single-arm pilot observational prospective trial of adult patients with essential or parkinsonian tremor from 2013 to 2019 and report results at one-year follow-up. Patients were treated with frameless unilateral radiosurgical ablation of the thalamic ventral intermediate nucleus to a maximum dose of 160 Gy. Treatment response was measured by the Fahn-Tolosa-Marin (FTM) tremor rating scale and the Quality of Life in Essential Tremor or Parkinson s Disease Questionnaire obtained prior to treatment and at 3, 6, 9, and 12 months.\n\n\nRESULTS\nThirty-three patients, including 23 with essential tremor and 10 with Parkinson s disease, were enrolled. Overall treatment response rate per FTM was 83% (n=15/18) at 6 months. There was a marked improvement in tremor, with average total FTM reduction of 21% at 3 months (from 46 to 30 points, p=0.003) and 41% at 6 months (from 46 to 24 points, p=0.001). At 6 months, functional decline had regressed by 54% (from 15 to 7 points, p=0.001). Quality of life improved by 57% (p=0.001) at 6 months in patients with essential tremor, and patients with Parkinson s Disease had unchanged quality of life. At one-year follow-up, grade 2 neurologic adverse events were observed in 6% (n=2/33) of patients without any grade ≥ 3 events.\n\n\nCONCLUSION\nNoninvasive, frameless radiosurgical thalamotomy may be a feasible treatment for patients with refractory tremor and demonstrates short-term safety at one-year follow-up. This pilot study provides promising preliminary descriptions of efficacy, and definitive estimates of long-term safety and benefit require further study with longer follow-up.