Focused Ultrasound Thalamotomy in Tremor Dominant Parkinson's Disease: Long-Term Results

Motor and non-motor outcome in tremor dominant Parkinson's disease after MR-guided focused ultrasound thalamotomy

BACKGROUND AND OBJECTIVES

Magnetic Resonance-guided Focused Ultrasound (MRgFUS) is an emerging technique for the treatment of severe, medication-refractory tremor syndromes. We here report motor and non-motor outcomes 6 and 12 months after unilateral MRgFUS thalamotomy in tremor-dominant Parkinson's disease (tdPD).

METHODS

25 patients with tdPD underwent neuropsychological evaluation including standardized questionnaires of disability, quality of life (QoL), mood, anxiety, apathy, sleep disturbances, and cognition at baseline, 6 and 12 months after MRgFUS. Motor outcome was evaluated using the Clinical Rating Scale for Tremor (CRST) and Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS). In addition, side effects and QoL of family caregivers were assessed.

RESULTS

12 months after MRgFUS significant improvements were evident in the tremor subscores. Patients with concomitant rest and postural tremor showed better tremor outcomes compared to patients with predominant rest tremor. There were no differences in the non-motor assessments. No cognitive decline was observed. Side effects were mostly transient (54%) and classified as mild (62%). No changes in the caregivers' QoL could be observed.

CONCLUSION

We found no changes in mood, anxiety, apathy, sleep, cognition or persistent worsening of gait disturbances after unilateral MRgFUS thalamotomy in tdPD. Concomitant postural tremors responded better to treatment than predominant rest tremors.

Clinical neurophysiology in the treatment of movement disorders: IFCN handbook chapter

In this review, different aspects of the use of clinical neurophysiology techniques for the treatment of movement disorders are addressed. First of all, these techniques can be used to guide neuromodulation techniques or to perform therapeutic neuromodulation as such. Neuromodulation includes invasive techniques based on the surgical implantation of electrodes and a pulse generator, such as deep brain stimulation (DBS) or spinal cord stimulation (SCS) on the one hand, and non-invasive techniques aimed at modulating or even lesioning neural structures by transcranial application. Movement disorders are one of the main areas of indication for the various neuromodulation techniques. This review focuses on the following techniques: DBS, repetitive transcranial magnetic stimulation (rTMS), low-intensity transcranial electrical stimulation, including transcranial direct current stimulation (tDCS) and transcranial alternating current stimulation (tACS), and focused ultrasound (FUS), including high-intensity magnetic resonance-guided FUS (MRgFUS), and pulsed mode low-intensity transcranial FUS stimulation (TUS). The main clinical conditions in which neuromodulation has proven its efficacy are Parkinson's disease, dystonia, and essential tremor, mainly using DBS or MRgFUS. There is also some evidence for Tourette syndrome (DBS), Huntington's disease (DBS), cerebellar ataxia (tDCS), and axial signs (SCS) and depression (rTMS) in PD. The development of non-invasive transcranial neuromodulation techniques is limited by the short-term clinical impact of these techniques, especially rTMS, in the context of very chronic diseases. However, at-home use (tDCS) or current advances in the design of closed-loop stimulation (tACS) may open new perspectives for the application of these techniques in patients, favored by their easier use and lower rate of adverse effects compared to invasive or lesioning methods. Finally, this review summarizes the evidence for keeping the use of electromyography to optimize the identification of muscles to be treated with botulinum toxin injection, which is indicated and widely performed for the treatment of various movement disorders.

MR-guided focused ultrasound in movement disorders and beyond: Lessons learned and new frontiers

The development of MR-guided focused ultrasound (MRgFUS) has provided a new therapeutic tool for neuropsychiatric disorders. In contrast to previously available neurosurgical techniques, MRgFUS allows precise impact on deep brain structures without the need for incision and yields an immediate effect. In its high-intensity modality (MRgHIFU), it produces accurate therapeutic thermoablation in previously selected brain targets. Importantly, the production of the lesion is progressive and highly controlled in real-time by both neuroimaging and clinical means. MRgHIFU ablation is already an accepted and widely used treatment for medically-refractory Parkinson's disease and essential tremor. Notably, other neurological disorders and diverse brain targets, including bilateral treatments, are currently under examination. Conversely, the low-intensity modality (MRgLIFU) shows promising prospects in neuromodulation and transient blood-brain barrier opening (BBBO). In the former circumstance, MRgLIFU could serve as a powerful clinical and research tool for non-invasively modulating brain activity and function. BBBO, on the other hand, emerges as a potentially impactful method to influence disease pathogenesis and progression by increasing brain target engagement of putative therapeutic agents. While promising, these applications remain experimental. As a recently developed technology, MRgFUS is not without challenges and questions to be addressed. Further developments and broader experience are necessary to enhance MRgFUS capabilities in both research and clinical practice, as well as to define device constraints. This clinical mini-review aims to provide an overview of the main evidence of MRgFUS application and to highlight unmet needs and future potentialities of the technique.

Scalp Nerve Block Alleviates Headaches Associated With Sonication During Transcranial Magnetic Resonance-Guided Focused Ultrasound

BACKGROUND AND OBJECTIVES

In magnetic resonance-guided focused ultrasound (MRgFUS) procedures, headache is a frequent symptom and cause of treatment discontinuation. Herein, we assessed the efficacy of scalp nerve block (SNB) for alleviating headache during MRgFUS procedures.

METHODS

The effect of SNB on intraprocedural headache was examined by retrospectively comparing 2 patient cohorts at a single institution. During the study period from April 2020 to February 2022, an SNB protocol for all patients with a skull density ratio ≤0.55 was instituted on October 6, 2021. The number of patients with a skull density ratio ≤0.55 was 34 before the protocol and 36 afterward. Headache intensity was evaluated using a numerical rating scale (NRS) after each sonication. To evaluate the effect of SNB on headache intensity, multiple regression analysis was performed per patient and per sonication. In the per-patient analysis, the effect of SNB was evaluated using the maximum NRS, mean NRS, and NRS at the first ultrasound exposure that reached 52.5°C. In the per-sonication analysis, the effect of SNB was evaluated not only for the entire sonication but also for sonications classified into ≤9999 J, 10 000 to 29 999 J, and ≥30 000 J energy doses.

RESULTS

With SNB, headache alleviation was observed in the NRS after the first sonication that reached 52.5°C in each patient (β = -2.40, 95% CI -4.05 to -0.758, P = .00499), in the NRS when all sonications were evaluated (β = -0.647, 95% CI -1.19 to -0.106, P = .0201), and in the NRS when all sonications were classified into 10 000 to 29 999 J (β = -1.83, 95% CI -3.17 to -0.485, P = .00889).

CONCLUSION

SNB significantly reduced headache intensity during MRgFUS, especially that caused by sonication with a moderate-energy dose. These findings suggest that scalp nerves play a role in headache mechanisms during MRgFUS.

Efficacy of Wearable low-intensity pulsed Ultrasound treatment in the Movement disorder in Parkinson's disease (the SWUMP trial): protocol for a single-site, double-blind, randomized controlled trial

BACKGROUND

Parkinson's disease (PD) is a progressive, neurodegenerative illness marked by the loss of dopaminergic neurons, causing motor symptoms. Oral levodopa replacement therapy remains the gold standard in the treatment of PD. It is, nevertheless, a symptomatic treatment. There is currently no effective treatment for PD. Therefore, new therapies for PD are highly desirable. Low-intensity pulsed ultrasound (LIPUS) has been shown to improve behavioral functions in PD animal models. It is a new type of neuromodulation approach that combines noninvasiveness with high spatial precision. The purpose of this study is to establish a new clinical protocol for LIPUS in the treatment of movement disorders in patients with PD.

METHODS

This protocol is a single-site, prospective, double-blind, randomized controlled trial (RCT). Forty-eight participants with clinically confirmed PD will be randomly allocated to one of two groups: LIPUS group or sham group. All of the participants continue to use pharmacological therapy as a fundamental treatment. The primary outcome is the difference between groups from baseline to 4 months in the change in the Unified Parkinson's Disease Rating Scale (UPDRS) motor score (part III). The secondary outcomes include the rating scales such as the Mini-Mental State Examination (MMSE), and other three rating scales, and medical examinations including high-density electroencephalography (hdEEG) and functional magnetic resonance imaging (fMRI). The primary safety outcome will be assessed at 4 months, and adverse events will be recorded.

DISCUSSION

This study represents the clinical investigation into the efficacy of therapeutic LIPUS in the treatment of PD for the first time. If LIPUS is determined to be effective, it could offer a practical and innovative means of expanding the accessibility of ultrasound therapy by using a wearable LIPUS device within a home setting.

TRIAL REGISTRATION

Chinese Clinical Trial Registry ChiCTR2100052093. Registered on 17 October 2021.

Bedside clinical assessment of patients with common upper limb tremor and algorithmic approach

The diagnostic approach for patients with tremor is challenging due to the complex and overlapping phenotypes among tremor syndromes. The first step in the evaluation of tremor is to identify the tremulous movement and exclude the tremor mimics. The second step is to classify the tremor syndrome based on the characteristics of tremor from historical clues and focused examination (Axis 1). Comprehensive tremor examinations involve the assessment of tremor in different conditions (rest, action or mixed, position or task-specific), distribution of tremor (upper limb, lower limb, head, jaw), positive signs for functional tremor (FT) if suspected (distractibility, entrainment, co-contraction), and associated neurological signs including parkinsonism, dystonic posture, cerebellar/brainstem signs, neuropathy, and cognitive impairment. A pivotal feature in this step is to determine any distinct feature of a specific isolated or combined tremor syndrome. In this review, we propose an algorithm to assess upper limb tremors. Ancillary testing should be performed if clinical evaluation is unclear. The choice of investigation depends on the types of tremors considered to narrow down the spectrum of etiology (Axis 2). Laboratory blood tests are considered for acute onset and acute worsening of tremors, while structural neuroimaging is indicated in unilateral tremors with acute onset, nonclassical presentations, and a combination of neurological symptoms. Neurophysiological study is an important tool that aids in distinguishing between tremor and myoclonus, etiology of tremor and document specific signs of FT. Treatment is mainly symptomatic based depending on the etiology of the tremor and the patient's disabilities.

Focused Ultrasound Thalamotomy for Tremor Relief in Atypical Parkisnsonism

Background

Magnetic resonance imaging (MRI)-guided focused ultrasound (FUS) VIM-thalamotomy has established efficacy and safety in tremor relief in patients with essential tremor and Parkinson's disease. The efficacy and safety in patients with atypical parkinsonism have not been reported.

Objective

To report on the efficacy and safety of FUS VIM-thalamotomy in 8 patients with parkinsonism, multiple system atrophy-Parkinsonian type (MSA-P) (n = 5), and dementia with Lewy bodies (DLB) (n = 3).

Methods

Tremor was assessed in the treated hemibody using the Clinical Rating Scale for Tremor (CRST). The motor Unified MSA Rating Scale (UMSAR) was used in the MSA-P and motor sections of the Unified Parkinson's Disease Rating Scale (UPDRS-III) in DLB patients. Cognition was measured using the Montreal Cognitive Assessment (MoCA).

Results

In MSA-P and DLB patients, there was immediate tremor relief. CRST scores measured on the treated side improved compared to baseline. During the follow-up of up to 1 year tremor reduction persisted. The change in CRST scores at different time points did not reach statistical significance, probably due to the small sample size. Adverse events were transient and resolved within a year.

Conclusions

In our experience, FUS VIM-thalamotomy was effective in patients with MSA-P and DLB. Larger, controlled studies are needed to verify our preliminary observations.

How to Use the New European Academy of Neurology/Movement Disorder Society European Section Guideline for Invasive Therapies in Parkinson's Disease

BACKGROUND

The decision to choose invasive treatments for Parkinson's disease (PD) is complex and needs careful consideration.

OBJECTIVES

Although the recommendations of the European Academy of Neurology/Movement Disorder Society European Section guideline for invasive therapies of PD are useful, the different clinical profiles of people with PD who seek advice for possible invasive therapy need further attention.

METHODS AND RESULTS

Here we describe 8 clinical standard situations of people with PD unsatisfied with their current oral treatment where invasive therapies may be considered. These are PD patients presenting with the following symptoms: (1) severe motor fluctuations, (2) beginning of levodopa-responsive fluctuations, severe tremor at (3) young or (4) advanced age, (5) impulse control disorders and related behavioral disorders, (6) hallucinations and psychosis, (7) minimal cognitive impairment or mild dementia, and (8) patients in need of palliative care. For some of these conditions, evidence at lower level or simple clinical considerations exist.

CONCLUSIONS

There are no one-fits-all answers, but physician and patient should discuss each option carefully considering symptom profile, psychosocial context, availability of therapy alternatives, and many other factors. The current paper outlines our proposed approach to these circumstances.

Magnetic resonance imaging-guided focused ultrasound thalamotomy launch with remote telemedicine international proctorship

Background

COVID-19 limitations have hindered the implementation of new technologies by preventing proctors from coming to the site. We share our first experience of magnetic resonance imaging (MRI)-guided focused ultrasound (MRgFUS) treatment with an international remote online proctorship, and develop and evaluate the methodology of remote MRgFUS proctorship.

Methods

This single-center, nonrandomized controlled prospective study included 94 patients: 27 with essential tremor (ET) and 67 with tremor-dominant Parkinson's disease (PD). The coming of proctors was impossible, so we arranged for the remote participation of proctors from the United Kingdom, Spain, and Israel. A total of 38 patients (40.4%) received telemedicine-proctored treatment (proctor group) and 56 received their treatment independently (solo group). We used the Clinical Rating Scale for Tremor (CRST) for ET patients and the Unified Parkinson's Disease Rating Scale (UPDRS) Part III for PD patients.

Results

In patients with ET, success rates were 81.8% (proctor group) and 100% (solo group) (p = 0.22). CRST reduction on the treated side was 71.43% [65.83%; 80.56%] (proctor group) versus 60.87% [53.99; 79.58] (solo group) (p = 0.19). None of the patients showed worsening of tremors within 1 year. In patients with PD, the success rates were 92.6% (proctor group) and 100% (solo group) (p = 0.08). The UPDRS Part III improvement was 30.1% (proctor group) versus 39.9% (solo group) (p = 0.003). The 1-year recurrence rate was 40% (proctor group) and 17.5% (solo group) (p = 0.04). No complications were observed at 6 months.

Conclusions

We developed a feasible and safe methodology for telemedicine remote online-proctored MRgFUS treatment. No significant difference was observed between the solo and developed remote proctor protocols in terms of complication rate, effect, and long-term results; however, UPDRS Part III improvement was better in the PD solo group. This study demonstrated that the MRgFUS international proctorship can be performed successfully remotely.

Outcomes of Focused Ultrasound Thalamotomy in Tremor Syndromes

BACKGROUND

The current literature comparing outcomes after a unilateral magnetic resonance image-guided focused ultrasound (MRgFUS) thalamotomy between tremor syndromes is limited and remains a possible preoperative factor that could help predict the long-term outcomes.

OBJECTIVE

The aim was to report on the outcomes between different tremor syndromes after a unilateral MRgFUS thalamotomy.

METHODS

A total of 66 patients underwent a unilateral MRgFUS thalamotomy for tremor between November 2018 and May 2020 at St Vincent's Hospital Sydney. Each patient's tremor syndrome was classified prior to treatment. Clinical assessments, including the hand tremor score (HTS) and Quality of Life in Essential Tremor Questionnaire (QUEST), were performed at baseline and predefined intervals to 36 months.

RESULTS

A total of 63 patients, comprising 30 essential tremor (ET), 24 dystonic tremor (DT), and 9 Parkinson's disease tremor (PDT) patients, returned for at least one follow-up. In the ET patients, at 24 months there was a 61% improvement in HTS and 50% improvement in QUEST compared to baseline. This is in comparison to PDT patients, where an initial benefit in HTS and QUEST was observed, which waned at each follow-up, remaining significant only up until 12 months. In the DT patients, similar results were observed to the ET patients: at 24 months there was a 61% improvement in HTS and 43% improvement in QUEST compared to baseline.

CONCLUSION

These results support the use of unilateral MRgFUS thalamotomy for the treatment of DT, which appears to have a similar expected outcome to patients diagnosed with ET. Patients with PDT should be warned that there is a risk of treatment failure. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Focused Ultrasound Thalamotomy for Tremor in Parkinson's Disease: Outcomes in a Large, Prospective Cohort

BACKGROUND

Magnetic resonance guided focused ultrasound (MRgFUS) is United States Food and Drug Administration approved for the treatment of tremor-dominant Parkinson's disease (TdPD), but only limited studies have been described in practice.

OBJECTIVES

To report the largest prospective experience of unilateral MRgFUS thalamotomy for the treatment of medically refractory TdPD.

METHODS

Clinical outcomes of 48 patients with medically refractory TdPD who underwent MRgFUS thalamotomy were evaluated. Tremor outcomes were assessed using the Fahn-Tolosa-Marin scale and adverse effects were categorized using a structured questionnaire and clinical exam at 1 month (n = 44), 3 months (n = 34), 1 year (n = 22), 2 years (n = 5), and 3 years (n = 2). Patients underwent magnetic resonance imaging <24 hours post-procedure.

RESULTS

Significant tremor control persisted at all follow-ups (P < 0.001). All side effects were mild. At 3 months, these included gait imbalance (38.24%), sensory deficits (26.47%), motor weakness (17.65%), dysgeusia (5.88%), and dysarthria (5.88%), with some persisting at 1 year.

CONCLUSIONS

MRgFUS thalamotomy is an effective treatment for sustained tremor control in patients with TdPD. © 2023 International Parkinson and Movement Disorder Society.

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.

Stereotactic robot-assisted MRI-guided laser interstitial thermal therapy thalamotomy for medically intractable Parkinson's disease tremor: technical note and preliminary effects on 2 cases

BACKGROUND

Medically intractable Parkinson's disease (PD) tremor is a common difficult clinical situation with major impact on patient's quality of life (QOL). Deep brain stimulation (DBS) is an effective therapy but is not an option for many patients. Less invasive lesional brain surgery procedures, such as thalamotomy, have proven to be effective in these indications. Here, we describe the technical nuances and advantages of stereotactic robot-assisted MRI-guided laser interstitial thermal therapy (MRIg-LITT) thalamotomy for medically intractable PD tremor.

METHOD

We describe 2 patients with medically intractable PD tremor treated with stereotactic robot-assisted MRIg-LITT thalamotomy performed under general anesthesia with intraoperative electrophysiological testing. Pre and postoperative tremor scores were assessed using the Fahn-Tolosa-Marin tremor rating scale (TRS).

RESULTS

At 3-month follow-up, both patients demonstrated significant improvement in tremor symptoms subjectively and according to the TRS (75% for both). Patients also had substantial improvements in their QOL (32.54% and 38%) according to the 39-item PD questionnaire. Both patients underwent uncomplicated MRIg-LITT thalamotomy.

CONCLUSIONS

In patients with medically intractable PD tremor who are unsuitable candidates for DBS, thalamotomy utilizing a stereotactic robot, intraoperative electrophysiological testing, and laser ablation with real-time MRI guidance may be a viable treatment option. However, further studies with larger sample sizes and longer follow-up periods are necessary to confirm these preliminary results.

[Experience of staged and simultaneous bilateral thalamotomy using MR-guided focused ultrasound in the treatment of essential tremor]

OBJECTIVE

To show that effective and safe bilateral MR-guided focused ultrasound (MRgFUS) treatment of essential tremor (ET) is achievable.

MATERIAL AND METHODS

Four male patients underwent bilateral thalamotomy. Two patients underwent staged thalamotomy, with the ≥12 month interval between operations. Two patients underwent simultaneous bilateral thalamotomy.

RESULTS

After six months, all patients noted a significant reduction in symptoms on both sides: when assessing tremors with the Clinical Rating Scale for Tremor, the severity of hyperkinesis decreased by 57.5-69.7%. We did not observe any complications in any of the cases.

CONCLUSION

Our experience indicates that simultaneous bilateral MRI-guided focused ultrasound treatment of ET can be performed safely and effectively. Further research is necessary to estimate the effectiveness and adverse effect rates.

Pharmacological Treatment of Tremor in Parkinson's Disease Revisited

The pathophysiology of Parkinson's disease (PD) tremor remains incompletely understood and there is a lack of clinical trials specifically addressing its pharmacological treatment. Levodopa is the most efficacious drug for most patients and should be used as primary approach to control troublesome tremor. While the efficacy of oral dopamine agonists on PD tremor has been demonstrated in controlled trials, there is no evidence of greater antitremor efficacy compared to levodopa. The magnitude of the antitremor effect of anticholinergics is generally lower than that of levodopa. Due to their adverse effects, anticholinergics have a limited role in selected young and cognitively intact patients. Propranolol may improve resting and action tremor and may be considered as an adjunct in patients with insufficient tremor response to levodopa and this also applies to clozapine, despite its unfavorable adverse effect profile. Treating motor fluctuations with MAO-B and COMT inhibitors, dopamine agonists, amantadine, or on-demand treatments such as subcutaneous or sublingual apomorphine and inhaled levodopa as well as with continuous infusions of levodopa or apomorphine will improve off period tremor episodes. For patients with drug-refractory PD tremor despite levodopa optimization deep brain stimulation and focused ultrasound are first-line considerations. Surgery can also be highly effective for the treatment medication-refractory tremor in selected patients without motor fluctuations. The present review highlights the clinical essentials of parkinsonian tremor, critically examines available trial data on the effects of medication and surgical approaches and provides guidance for the choice of treatments to control PD tremor in clinical practice.

Magnetic Resonance-Guided Focused Ultrasound Thalamotomy May Spare Dopaminergic Therapy in Early-Stage Tremor-Dominant Parkinson's Disease: A Pilot Study

BACKGROUND

Magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy is a safe and effective procedure for drug-resistant tremor in Parkinson's disease (PD).

OBJECTIVE

The aim of this study was to demonstrate that MRgFUS ventralis intermedius thalamotomy in early-stage tremor-dominant PD may prevent an increase in dopaminergic medication 6 months after treatment compared with matched PD control subjects on standard medical therapy.

METHODS

We prospectively enrolled patients with early-stage PD who underwent MRgFUS ventralis intermedius thalamotomy (PD-FUS) and patients treated with oral dopaminergic therapy (PD-ODT) with a 1:2 ratio. We collected demographic and clinical data at baseline and 6 and 12 months after thalamotomy.

RESULTS

We included 10 patients in the PD-FUS group and 20 patients in the PD-ODT group. We found a significant increase in total levodopa equivalent daily dose and levodopa plus monoamine oxidase B inhibitors dose in the PD-ODT group 6 months after thalamotomy.

CONCLUSIONS

In early-stage tremor-dominant PD, MRgFUS thalamotomy may be useful to reduce tremor and avoid the need to increase dopaminergic medications. © 2022 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Comparison of Motor Scores between OFF and ON States in Tremor-Dominant Parkinson's Disease after MRgFUS Treatment

Objective: To compare the motor function improvements in ON and OFF states in tremor-dominant Parkinson’s disease (TDPD) patients within one year of follow-up after ablation of the unilateral ventral intermediate nucleus of the thalamus (Vim) by magnetic resonance imaging-guided focused ultrasound surgery (MRgFUS). Methods: A total of nine consecutive patients confirmed with TDPD who underwent unilateral Vim ablation by MRgFUS between April 2019 and September 2019 were included. The Movement Disorder Society Unified Parkinson’s Disease Rating Scale part III (MDS-UPDRSIII) and Clinical Rating Scale for Tremor (CRST) were performed in the ON and OFF stages to distinguish the surgical effects from drug therapy effects. The adverse events and adjustment of drug doses were also recorded. Results: The preoperative MDS-UPDRSIII score in OFF and ON states was 55.0 (48.0, 65.5) and 26.0 (17.0, 27.0), while the CRST score was 46.0 (39.5, 53.5) and 20.0 (13.0, 23.5), respectively; the Levodopa equivalent dose was 600 (456, 600) mg/d. At 1 year after operation, the total MDS-UPDRSIII score and CRST score were 40.0 (30.0, 60.5) and 16.0 (10.0, 29.5) in the OFF state, and 21.0 (17.5, 27.0) and 2.0 (1.5, 7.0) in the ON state, respectively. Compared with the preoperative levels, follow-up at the two-time points (three months and one year after operation) showed the total MDS-UPDRSIII score, as well as MDS-UPDRSIII tremor, bradykinesia, and rigidity scores of contralateral limbs all significantly improved in OFF state. However, in the ON state, only the total MDS-UPDRSIII score and tremor score of contralateral limbs significantly improved. The total CRST score and the CRST (A + B) score of contralateral limbs significantly improved at three months and one year after the operation compared with before the operation in both ON and OFF states. The Levodopa equivalent dose at one and three months were not significantly different from the preoperative dose (p > 0.05). No serious adverse responses were observed. Conclusion: Treating TDPD with unilateral Vim ablation by MRgFUS could improve the symptoms of limb tremor and the other core symptoms, such as bradykinesia and rigidity, as well as some non-motor symptoms and the symptoms of ipsilateral limbs.

Update in the clinical application of focused ultrasound

PURPOSE OF REVIEW

To review the most recent evidence about the clinical applicability of transcranial MRI-guided focused ultrasound (MRgFUS), including clinical evidence and indications, recent technical developments for its use and future prospects.

RECENT FINDINGS

Unilateral MRgFUS thalamotomy for both essential and parkinsonian tremors is an approved and well established therapy. Recent studies have focused on its long-term safety and efficacy as well as technical advances for refining the approach. Moreover, ultrasound has expanded its application in Parkinson's disease, with clinical trials successfully targeting other brain regions like the subthalamic nucleus, the globus pallidus and the pallidothalamic tract, providing benefits for features that thalamotomy neglects. New indications, such as focal dystonia or neuropsychiatric conditions (namely obsessive-compulsive disorder and depression) have also been explored, with encouraging preliminary results. Finally, the application of ultrasound in low-intensity modality allows other approaches like focal blood-brain barrier opening and neuromodulation, which promise to be highly relevant in translational research.

SUMMARY

MRgFUS is a growing emergent technique. Its application in clinical routine is becoming widely accepted as a therapeutic option. Novel approaches and new potential applications are anticipated.

Ultrasound-Mediated Bioeffects in Senescent Mice and Alzheimer's Mouse Models

Ultrasound is routinely used for a wide range of diagnostic imaging applications. However, given that ultrasound can operate over a wide range of parameters that can all be modulated, its applicability extends far beyond the bioimaging field. In fact, the modality has emerged as a hybrid technology that effectively assists drug delivery by transiently opening the blood–brain barrier (BBB) when combined with intravenously injected microbubbles, and facilitates neuromodulation. Studies in aged mice contributed to an insight into how low-intensity ultrasound brings about its neuromodulatory effects, including increased synaptic plasticity and improved cognitive functions, with a potential role for neurogenesis and the modulation of NMDA receptor-mediated neuronal signalling. This work is complemented by studies in mouse models of Alzheimer’s disease (AD), a form of pathological ageing. Here, ultrasound was mainly employed as a BBB-opening tool that clears protein aggregates via microglial activation and neuronal autophagy, thereby restoring cognition. We discuss the currently available ultrasound approaches and how studies in senescent mice are relevant for AD and can accelerate the application of low-intensity ultrasound in the clinic.

[The problem of pharmacoresistant tremor in Parkinson's disease and essential tremor]

MR-guided focused ultrasound (MRg-FUS) is a new noninvasive method for the treatment of contralateral disabling and pharmacoresistant tremor. Clinical studies have confirmed the high efficacy and safety of using MRg-FUS in patients with essential tremor and Parkinson's disease, in short and long-term studies. Advantages of this method in comparison with currently used invasive and noninvasive technics, potential brain target areas, the possibility of bilateral intervention, indications and contraindications are discussed.