Objective: To report long-term outcome of unilateral MR-guided focused ultrasound(MRgFUS) subthalamotomy for the treatment of PD cardinal motor features.

Background: The development of MRgFUS as a minimally invasive approach to perform focal lesions in deep brain structures has revitalized ablation as a therapeutic approach for MDs.MRgFUS unilateral thalamotomy is an approved treatment for both essential(1) and parkinsonian tremor(2).Recently,two pilot studies showed safety and preliminary efficacy of both MRgFUS unilateral subthalamotomy(3) and pallidotomy(4) for the treatment of PD motor features.

Method: 7 out of 10 patients who had undergone unilateral MRgFUS subthalamotomy(April-June 2016) were followed-up for 24-30 months.Assessments included change from baseline of MDS-UPDRS III for the treated and untreated body sides,total motor MDS-UPDRS III,PDQ-39 for QoL,MDS-UPDRS II for activities of daily living and patient’s global impression of improvement(PGI-I).MDS-UPDRS III was evaluated after 24h of drug withdrawal for the OFF state and after taking patient’s daily levodopa dose for the ON state.LEDDs were calculated.Treatment-related adverse events were registered.Wilcoxon-t was used for comparison from baseline to last follow-up.

Results: Table 1 shows baseline characteristics of the sample.Significant improvements from baseline were evident in the MDS-UPDRS III score for the treated side in both the off(36%,p=0.03) and on-drug(47%,p=0.02) states.(Figure 1)Contralateral rigidity and tremor remained significantly improved at last follow-up(48% off-med and 63% on-med,p=0.03 for rigidity, and 69% both off-med and on-med,p=0.02 for tremor) but not bradykinesia(9% and 17%,p=NS).Non-treated side worsened in both the off- (36%;p=0.03) and on-period (48%;p=0.02).Total MDS-UPDRS III improvements in off(15%) and on(22%) did not reach significance.MDS-UPDRS II remained stable from baseline (6.4±3.7 vs 5.1±3.6;p=NS) while PDQ-39 scores did not worse(9.6±8.5 vs 11.5±9;p=NS).LEDD remained stable (620±276 vs 565±222;p=NS).No long-term side effects appeared.No off-dyskinesias were observed at last follow-up.

Conclusion: Our results suggest that the benefits on PD motor features after unilateral MRgFUS subthalamotomy are sustained in the long-term for rigidity and tremor.The decayed in benefit observed for bradykinesia deserves further analysis for better understanding and optimization of the technique.

References: 1. Elias WJ, Lipsman N, Ondo WG, et al. A randomized trial of focused ultrasound thalamotomy for essential tremor. N Engl J Med 2016; 375: 730–39. 2. Bond AE, Shah BB, Huss DS, et al. Safety and Efficacy of Focused Ultrasound Thalamotomy for Patients with Medication-Refractory, Tremor-Dominant Parkinson Disease: A Randomized Clinical Trial. JAMA Neurol. 2017 Dec 1;74(12):1412-1418. 3. Martínez-Fernandez R, Rodríguez-Rojas R, del Álamo M et al. Focused ultrasound subthalamotomy in patients with asymmetric Parkinson’s disease: a pilot study. Lancet Neurol 2018; 17: 54–63. 4. Jung NY, Park CK, Kim M et al. The efficacy and limits of magnetic resonance-guided focused ultrasound pallidotomy for Parkinson’s disease: a Phase I clinical trial.J Neurosurg. 2018 Aug 1:1-9.

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MDS Abstracts - https://www.mdsabstracts.org/abstract/long-term-follow-up-of-unilateral-focused-ultrasound-subthalamotomy-for-the-treatment-of-motor-features-in-asymmetric-pd/