Objective: To evaluate feasibility, safety and effectiveness of unilateral subthalamotomy performed with MRIgHIFU to treat the cardinal motor features of PD

Background: Ablative functional neurosurgery for the treatment of movement disorders and, particularly, of Parkinson`s disease (PD) has been applied for decades. However, after the resurgence of deep brain stimulation, lesional procedures were practically abandoned. In the case of subthalamotomy, the main reason was the concern of inducing hemichorea-hemiballism. This is now revisited due to the development of MRI guided high intensity focused ultrasound (MRIgHIFU)

Methods: This is an open-label, single center study. Ten PD patients with markedly asymmetric parkinsonism who were not optimally controlled with medication were entered into the study. Motor features were assessed by the MDS-UPDRS III at baseline, 1 month, 3 months and 6 months after treatment. Motor complications were evaluated through MDS-UPDRS IV and the Dyskinesia rating scale (DRS). PDQ39 provided an estimation of patient’s quality of life. Levodopa daily equivalents were measured. Adverse events were recorded

Results: Ten patients (6 males) were treated. Mean age was 59.5 and disease evolution 6.3±2.5 years (range, 3 to 10). MDS-UPDRS III score for the treated hemibody presented a reduction of 55 and 51% between baseline and 6-month visit in the off and on-drug states respectively (from 16.6±2.9 to 7.5 ± 3.9 and from 11.9±3.1 to 5.8±3.5, p<0.001). Total motor MDS-UPDRS improved up to 35 and 32% (from 32.7±5.4 to 21.2±8.2 p<0.005, and from 21.5±6.3 to 14.5±5.3 P=0.02). In both off and on conditions rigidity was the most improved motor feature (72% and 91% p<0.001, respectively) whereas akinesia was the least (40% p=0.01, and 28% p=0.07, respectively). Subthalamotomy resulted in no change in dyskinesia scores whereas off-dystonia improved significantly in both the MDS-UPDRS IV and DRS assessments. No significant changes were found in the PDQ39SI. Levodopa equivalents were reduced by 23% (p=0.003). There was no hemichorea-ballism immediately after treatment. One patient developed upper limb chorea 5 days after treatment that progressively reduce and was minimal at 6 months 

Conclusions: This pilot study suggests that MRIgHIFU subthalamotomy is feasible, safe and effective for the treatment of PD motor features. Randomized control trial with a larger sample is mandatory to confirm this promising evidence

References: 1. Alvarez L, Macias R, Pavon N, et al. Therapeutic efficacy of unilateral subthalamotomy in Parkinson’s disease: results in 89 patients followed for up to 36 months. Journal of neurology, neurosurgery, and psychiatry 2009;80:979-85.

2. Elias WJ, Huss D, Voss T, et al. A pilot study of focused ultrasound thalamotomy for essential tremor. The New England journal of medicine 2013;369:640-8.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/focused-ultrasound-subthalamotomy-for-parkinsons-disease-a-pilot-study/