Objective: To evaluate the safety, feasibility, and durability of focused ultrasound thalamotomy on tremor in PD.

Background: Surgical treatment of PD currently involves deep brain stimulation; with radiofrequency lesioning of the GPi and VIM used to a lesser degree. Benefit with these is well established, though many patients with disabling symptoms do not pursue these due to preference and surgical risk.

Methods: A study of PD subjects with tremor-dominant PD was performed with unilateral thalamotomy to the side contralateral to their most symptomatic side. At 3 months all sham candidates were offered active treatment. Subjects must have had disabling tremor despite optimal medical therapy – at least 900 levodopa equivalents daily. The primary outcome measures were safety and change from baseline to 3 months of the Clinical Rating Scale for Tremor (CRST). Additional measures included the UPDRS part III change from baseline to 3 months.

Results: Currently, data for safety are available for 25 subjects and 16 for efficacy. Adverse effects for the treatment included headache 64%, dizziness 36%, nausea 16%, anxiety 12%, ataxia 24%, paresthesia treated hand 24%, paresthesia treated side face/lip/tongue 20%, and heat sensation on scalp 20%. Most of these AEs were transient and resolved the day of treatment or by 1 month.CRST total score was reduced from baseline to 3 months by a mean of 48.6% and UPDRS III by 23.6%. Among these all subjects had reduction in CRST score, two had no change in UPDRS III, and 1 had increase in UPDRS III from baseline to 3 months.

Conclusions: MRgFUS is a non-incisional modality for delivering thermal lesions to deep brain structures. Results from pilot studies of thalamotomy in ET have been promising. PD is a distinct disorder with progressive neurological features. Here we show that unilateral thalamotomy in PD can be effective in reducing tremor at 3 months, though benefit is not of consistent magnitude. Further, AEs, while mainly transient, are relatively frequent. Additional study in the PD population with this new technology is necessary to establish a safety profile and identify the ideal patient population.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/unilateral-focused-ultrasound-thalamotomy-in-tremor-dominant-parkinsons-disease/