Objective: To assess the 8-year outcome of unilateral MRI guided focused ultrasound (MRgFUS) ventral intermediate nucleus thalamotomy in tremor dominant Parkinson’s disease (TDPD) patients, with tremor non-responsive to levodopa.

Background: Long-term data on the effects of MRgFUS for TDPD patients beyond 5 years has not been reported.

Method: Four TDPD patients who completed 8 years follow-up were included. Tremor was assessed with Clinical Rating Scale for Tremor (CRST) and motor function was assessed with the Unified Parkinson’s Disease Rating Scale (UPDRS part III) overall and in the treated hemibody (hemi-CRST and hemi-UPDRS). Levodopa equivalent dose was calculated.

Results: Median age before MRgFUS was 61 years (range 51-66 years), with median disease duration of 6.5 years (range 2-10). Tremor was significantly improved immediately following MRgFUS in all patients. At 8-years following MRgFUS, mean hemi-CRST score was significantly improved as compared with baseline (baseline mean score 20, range 10-20 vs. mean score at 8 years 4, range 0-6, p=0.04). Mean total CRST score was improved at 8 years as compared with baseline but this did not reach statistical significance (baseline mean score 40, range 20-54 vs. score at 8 years 14, range 3-32 p=0.06). Hemi-UPDRS significantly improved as compared with baseline at 8 years (p=0.04) but total UPDRS did not. Levodopa equivalent increased significantly at 8 years (p=0.03). There were no adverse events following the procedure in these patients.

Conclusion: This study found that improvement in tremor following unilateral FUS MRgFUS thalamotomy in TDPD was sustained at 8 years with no adverse effects. As expected, LDED increased over time.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/eight-year-outcome-of-focused-ultrasound-thalamotomy-in-tremor-dominant-parkinsons-disease-patients/