Stepwise Dual-Target Magnetic Resonance-Guided Focused Ultrasound in Tremor-Dominant Parkinson Disease: A Feasibility Study

Stepwise dual-target magnetic resonance-guided focused ultrasound in tremor-dominant Parkinson disease: One-year follow-up

BACKGROUND AND PURPOSE

Magnetic resonance-guided focused ultrasound (MRgFUS) is a nonsurgical treatment for Parkinson disease (PD). Some selected anatomical structures can be targeted by MRgFUS in PD. However, there is no uniform target yet. We have reported that stepwise dual-target MRgFUS was successfully applied to treat refractory tremors with akinetic-rigid features in PD. It generated two precise thermal ablations in the ventral intermediate nucleus (VIM) and pallidothalamic tract (PTT). Here, we report more PD patients to verify the safety and efficacy of stepwise dual-target MRgFUS.

METHODS

Ten tremor-dominant PD patients (mean age = 66.7 ± 3.2 years, eight men) received the stepwise dual-target MRgFUS treatment with a series of primary and secondary outcome measures. The VIM and PTT were navigated based on brain magnetic resonance images. Outcome measures were categorized into primary and secondary assessments. The primary outcome measures consisted of resting tremor, action/kinetic tremor, rigidity, and bradykinesia. Secondary outcome measures encompassed non-motor symptoms scale of PD. Data collected at follow-up time points, including 1 day, 3 months, 6 months, and 1 year posttreatment, were compared with baseline data.

RESULTS

The severity of tremor and motor deficits represented by Clinical Rating Scale for Tremor parts A and B during off-medication status and Unified Parkinson's Disease Rating Scale III on the treated side were significantly improved (p < 0.05 by paired t-test) at 1-year follow-up. At the 1-year follow-up, significant improvement was observed in the non-motor symptoms scale. Additionally, no severe adverse effects were reported, except temporary treatment-related discomfort during the procedure.

CONCLUSIONS

In conclusion, stepwise dual-target MRgFUS emerges as a safe and effective therapeutic modality for PD patients, particularly in addressing medication-refractory tremor and akinetic-rigid syndrome.

Focused Ultrasound for Treatment of Movement Disorders: A Review of Non-Food and Drug Administration Approved Indications

INTRODUCTION

MRI-guided focused ultrasound (FUS) is an incisionless thermo-ablative procedure that may be used to treat medication-refractory movement disorders, with a growing number of potential anatomic targets and clinical applications. As of this article's publication, the only US Food and Drug Administration (FDA)-approved uses of FUS for movement disorders are thalamotomy for essential tremor (ET) and tremor-dominant Parkinson's Disease (PD), and pallidotomy for other cardinal symptoms of PD. We present a state-of-the-art review on all non-FDA approved indications of FUS for movement disorders, beyond the most well-described indications of ET and PD. Our objective was to summarize the safety and efficacy of FUS in this setting and provide a roadmap for future directions of FUS for movement disorders.

METHODS

A state-of-the-art review was conducted on use of FUS for non-FDA approved movement disorders. All movement disorders excluding FDA-approved uses for ET and PD were included.

RESULTS

A total of 25 studies on 172 patients were included. In patients with tremor plus dystonia syndromes (n = 6), ventralis intermediate nucleus of the thalamus (VIM)-FUS gave >50% tremor reduction, with no improvement in dystonia and worsened dystonia in 2/6 patients. Ventral-oralis complex (VO)-FUS gave >50% improvement for focal hand dystonia (n = 6) and 100% return to musical performance in musician's dystonia (n = 6). In patients with multiple sclerosis (MS) and tremor (n = 3), improvement in tremor was seen in 2 patients with a favorable skull density ratio; no MS disease change was noted after VIM-FUS. In patients with tremor and comorbid ataxia syndromes (n = 3), none were found to have worsened ataxia after VIM-FUS; all had clinically significant tremor improvement. Subthalamic nucleus (STN)-FUS for PD (n = 49) gave approximately 50% improvement in PD motor symptoms, with dystonia and mild dyskinesias as possible adverse effects. Cerebellothalamic tract (CTT-FUS) for ET (n = 42) gave 55-90% tremor improvement, with gait dysfunction as a rare persistent adverse effect. Pallidothalamic tract (PTT-FUS) for PD (n = 50) gave approximately 50% improvement in motor symptoms, with mild speech dysfunction as a possible adverse effect.

CONCLUSION

VIM-FUS appeared safe and effective for heterogenous tremor etiologies, and VO-FUS appeared most effective for isolated segmental dystonia. STN-FUS was effective for PD symptom reduction; postoperative dystonia and mild on-medication dyskinesias required medical management. Tractography-based targeting with CTT-FUS for ET and PTT-FUS for PD demonstrated promising early results. Larger prospective trials with long-term follow-up are needed to the evaluate the safety and efficacy non-FDA approved indications for FUS.

Efficacy and safety of magnetic resonance-guided focused ultrasound for Parkinson's disease: a systematic review and meta-analysis

Objective

Magnetic resonance imaging-guided focused ultrasound (MRgFUS) is a novel noninvasive treatment for drug-resistant Parkinson's disease (PD) related tremor. This study aims to evaluate MRgFUS's efficacy and safety in PD through a systematic review and meta-analysis, examining pre-and post-treatment MDS-UPDRSIII and/or CRST scores and associated adverse events.

Materials and methods

We conducted an extensive literature search across PubMed, Embase, Web of Science, and Cochrane Library databases, screening studies based on set criteria and analyzing MDS-UPDRSIII, CRST, and adverse events pre- and post-MRgFUS treatment.

Results

Out of 468 retrieved articles, 20 studies involving 258 patients, spanning 2014-2023, were included.17 studies indicated significant MDS-UPDRSIII score reductions post-MRgFUS treatment, while 3 showed significant CRST score declines. In the "on" medication state, pooled MDS-UPDRSIII scores at 1, 3, 6, and 12 months were 12.18 (95% CI: 5.83-18.52), 12.10 (95% CI: 8.22-15.97), 14.85 (95% CI: 9.28-20.41), and 20.65 (95% CI: 12.15-29.14) respectively. In the "off" state, scores were 11.45 (95% CI: -3.50-26.40), 14.71 (95% CI: 4.95-24.46), 21.52 (95% CI: 19.28-23.75), and 22.28 (95% CI: 15.26-29.30). Adverse events were typically mild and transient, with speech disturbances, ataxia, and sensory abnormalities being common post-operative neurological complications.

Conclusion

MRgFUS offers an effective and relatively safe treatment option for patients with drug-resistant PD-related tremor.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, No. CRD42023428332.

Focused ultrasound thalamotomy for tremor treatment impacts the cerebello-thalamo-cortical network

High-intensity Magnetic Resonance-guided Focused Ultrasound (MRgFUS) is a recent, non-invasive line of treatment for medication-resistant tremor. We used MRgFUS to produce small lesions in the thalamic ventral intermediate nucleus (VIM), an important node in the cerebello-thalamo-cortical tremor network, in 13 patients with tremor-dominant Parkinson's disease or essential tremor. Significant tremor alleviation in the target hand ensued (t(12) = 7.21, p < 0.001, two-tailed), which was strongly associated with the functional reorganization of the brain's hand region with the cerebellum (r = 0.91, p < 0.001, one-tailed). This reorganization potentially reflected a process of normalization, as there was a trend of increase in similarity between the hand cerebellar connectivity of the patients and that of a matched, healthy control group (n = 48) after treatment. Control regions in the ventral attention, dorsal attention, default, and frontoparietal networks, in comparison, exhibited no association with tremor alleviation and no normalization. More broadly, changes in functional connectivity were observed in regions belonging to the motor, limbic, visual, and dorsal attention networks, largely overlapping with regions connected to the lesion targets. Our results indicate that MRgFUS is a highly efficient treatment for tremor, and that lesioning the VIM may result in the reorganization of the cerebello-thalamo-cortical tremor network.