Objective: We present results of an ongoing trial of unilateral transcranial MR-guided high intensity focused ultrasound (tcMRgFUS) ablation of the pallido-thalamic tract (PTT, fasciculus thalamicus) in Parkinson’s disease (PD).

Background: TcMRgFUS is a novel technique which allows ablation of deep brain structures under direct MR guidance without affecting surrounding tissue. The Subthalamic nucleus, Globus Pallidus internus and ventral intermediate nucleus of the thalamus are established stereotactic targets to treat parkinsonism. Radiofrequency ablation of the PTT within the subthalamic area is an effective approach to treat Parkinsonian symptoms like bradykinesia, tremor and rigidity.

Methods: The data of 3 patients with PD are collected retrospectively and of 2 patients prospective interim results of an ongoing trial. PD patients fulfilling current criteria for DBS therapy received ablation of the PTT using the ExAblate Neuro tcMRgFUS system. Reasons against DBS were anatomical issues, malcompliance and patients’ preference. The UPDRS III Score was recorded prior to and 6 months after the intervention. Pre- and 6 month post intervention neuropsychological assessments are available for 2 patients and scheduled for the other 3 patients. One patient has not yet reached the 6 months examinations.

Results: 5 patients with PD (4 tremor dominant, 1 with equivalent rigor and tremor, mean age 61.1 ± 13.7 yrs, mean disease duration 8.9 ± 5.1 yrs) were included. In 4 patients a unilateral (2 left, 2 right) and in 1 patient a bilateral PTT-ablation was performed. The mean On-UPDRS III score improved from 30.6 ± 10.5 at baseline to 8.8 ± 4.3 at 6 months after tcMRgFUS. The Hoehn and Yahr scale improved in one patient from 3 to 2 and did not change in the others. Reported side effects were one case of transient dysphagia, one case of dysphagia 8 months after unilateral PTT ablation unlikely to be linked to tcMRgFUS therapy and one case of infection of the urinary tract after catheterization. No other adverse events were observed.

Conclusions: Our interim results show that unilateral tcMRgFUS of the PTT seems to be a safe and effective interventional treatment option in PD. This needs to be substantiated further by additional prospective data.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/mr-guided-high-intensity-focused-ultrasound-in-parkinsons-disease-a-series-of-5-cases/