Magnetic Resonance-Guided Focused Ultrasound (MRgFUS)-Thalamotomy for Essential Tremor: Lesion Location and Clinical Outcomes.

BACKGROUND: Factors predicting clinical outcomes after MR-guided focused ultrasound (MRgFUS)-thalamotomy in patients with essential tremor (ET) are not well known. OBJECTIVE: To examine the clinical outcomes and their relationship with patients' baseline demographic and clinical features and lesion characteristics at 6-month follow-up in ET patients. METHODS: A total of 127 patients were prospectively evaluated at 1 (n = 122), 3 (n = 102), and 6 months (n = 78) after MRgFUS-thalamotomy. Magnetic resonance imaging (MRI) was obtained at 6 months (n = 60). Primary outcomes included: (1) change in the Clinical Rating Scale of Tremor (CRST)-A+B score in the treated hand and (2) frequency and severity of adverse events (AEs) at 6 months. Secondary outcomes included changes in all subitems of the CRST scale in the treated hand, CRST-C, axial tremor (face, head, voice, tongue), AEs, and correlation of primary outcomes at 6 months with lesion characteristics. Statistical analysis included linear mixed, standard, and logistic regression models. RESULTS: Scores for CRST-A+B, CRST-A, CRST-B in the treated hand, CRST-C, and axial tremor were improved at each evaluation (P < 0.001). Five patients had severe AEs at 1 month that became mild throughout the follow-up. Mild AEs occurred in 71%, 45%, and 34% of patients at 1, 3, and 6 months, respectively. Lesion volume was associated with the reduction in the CRST-A (P = 0.003) and its overlapping with the ventralis intermedius nucleus (Vim) nucleus with the reduction in CRST-A+B (P = 0.02) and CRST-B (P = 0.008) at 6 months. CONCLUSIONS: MRgFUS-thalamotomy improves hand and axial tremor in ET patients. Transient and mild AEs are frequent. Lesion volume and location are associated with tremor reduction. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Unilateral Magnetic Resonance Imaging-Guided Laser Interstitial Thermal Therapy Thalamotomy for Essential Tremor.

BACKGROUND: Essential tremor (ET) affects numerous adults, impacting quality of life (QOL) and often defying pharmacological treatment. Surgical interventions like deep brain stimulation (DBS) and lesional approaches, including radiofrequency, gamma-knife radiosurgery, and magnetic resonance imaging (MRI)-guided focused ultrasound, offer solutions but are not devoid of limitations. OBJECTIVES: This retrospective, single-center, single-blinded pilot study aimed to assess the safety and efficacy of unilateral MRI-guided laser interstitial thermal therapy (MRIg-LITT) thalamotomy for medically intractable ET. METHODS: Nine patients with ET, unresponsive to medications and unsuitable for DBS, underwent unilateral MRIg-LITT thalamotomy. We assessed tremor severity, QOL, cognitive function, and adverse events (AE) over a 12-month period. RESULTS: Tremor severity significantly improved, with a reduction of 83.37% at 12 months post-procedure. QOL scores improved by 74.60% at 12 months. Reported AEs predominantly included transient dysarthria, proprioceptive disturbances, and gait balance issues, which largely resolved within a month. At 3 months, 2 patients (22%) exhibited contralateral hemiparesis requiring physiotherapy, with 1 patient (11%) exhibiting persistent hemiparesis at 12 months. No significant cognitive impairment was detected post-procedure. CONCLUSIONS: Unilateral MRIg-LITT thalamotomy yielded substantial and enduring tremor alleviation and enhanced QOL in patients with ET that is resistant to medication. The AE profile was acceptable. Our findings support the need for additional research with expanded patient cohorts and extended follow-up to corroborate these outcomes and to refine the role of MRIg-LITT as a targeted and minimally invasive approach for ET management. © 2024 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

Radiosurgical thalamotomy for the management of tremors: a systematic review and meta-analysis.

Medical treatment for tremors may include beta-blockers, primidone, dopaminergic, and anticholinergic drugs but it frequently leads to pharmacoresistance. Therefore, surgical treatment gained relevance as an alternative for those patients.We aim to evaluate radiosurgical thalamotomy as an effective and safe alternative to manage tremors. Pubmed (MEDLINE), Embase, Web of Science, and the Cochrane Library databases were systematically searched for potential articles that evaluated radiosurgical thalamotomy for the management of tremor. Our analysis included 12 studies with 545 patients, 226 of whom were female. Of these, 64.6% of patients were diagnosed with essential tremor (ET), 34.6% with Parkinson's disease (PD), and 0.8% with both ET and PD. The FTM-TRS global score (MD -5.46; 95% CI [-10.44]-[-0.47]; I2 = 52%) and the drawing (MD -1.40; 95% CI [-2.03]-[-0.76]; I2 = 93%), drinking (MD -1.60; 95% CI [-1.82]-[-1.37]; I2 = 40%), and writing (MD -1.51; 95% CI [-1.89]-[-1.13]; I2 = 89%) grades showed significantly lower mean differences, favoring radiosurgical thalamotomy. A pooled proportion of 12% presented with tremor unchanged, while 38% presented with total elimination of tremor. Adverse events included: major paresis, minor paresis, dysarthria, and numbness. Thus, radiosurgical thalamotomy is a safe alternative for tremors resistant to medication, particularly in high-risk patients for RF or DBS procedures. The recommended dose of 130 to 150 Gy is effective and well-tolerated. However, randomized controlled trials (RCTs) are needed to understand the unpredictability of tissue response to radiation.

Hand Dystonia after Focused Ultrasound Thalamotomy in Essential Tremor.

INTRODUCTION: Magnetic resonance guided focused ultrasound (MRgFUS) thalamotomy is an effective treatment for drug-resistant tremor. The most frequent side effects are ataxia, gait disturbance, paresthesias, dysgeusia, and hemiparesis. Here, we report the first case of thalamic hand dystonia rapidly occurring after MRgFUS thalamotomy of the ventral intermediate nucleus (V.im). CASE PRESENTATION: MRgFUS thalamotomy was performed in a 60-year-old left-handed patient for his disabling medically refractory essential tremor. The intervention resulted in a marked reduction of his action tremor. However, the patient developed an unvoluntary abnormal posture in his left hand a few days after the procedure with difficulty holding a cigarette between his fingers. Brain MRI revealed the expected MRgFUS lesion within the right V.im as well as an extension of the lesion anteriorly to the V.im in the ventro-oralis nucleus. Tractography showed that the lesion disrupted the dentato-rubro-thalamic tract as expected with a lesion suppressing tremor. However, the lesion also was interrupted fibers connecting to the superior frontal and pre-central cortices (primary motor cortex, premotor cortex, and supplementary area). We hypothesized that the interventional MRgFUS thalamotomy was slightly off target, which induced a dysfunction within the cortico-striato-thalamo-cortical network and the cerebello-thalamo-cortical pathway reaching a sufficient threshold of basal ganglia/cerebellum circuitry interference to induce dystonia. CONCLUSION: This rare side effect emphasizes the risk of imbalance within the dystonia network (i.e., basal ganglia-cerebello-thalamo-cortical circuit) secondary to V.im thalamotomy.

Unilateral gamma knife thalamotomy for tremor safety and efficacy in multimodal assessment: a prospective case-control study with two-year follow-up.

INTRODUCTION: Unilateral gamma knife thalamotomy (GKT) is a treatment option for pharmacoresistant tremor of various aetiologies. There have been to date no randomised controlled trials performed to assess its safety and efficacy. Our aim was to summarise a two-year multimodal observation of patients with tremor caused by Parkinson's Disease (PD) or essential tremor (ET). MATERIAL AND METHODS: 23 patients with PD (n = 12) or ET (n = 11) were included. They underwent assessments before, V0 (n = 23), and 12 months, V12 (n = 23), and 24 months, V24 (n = 15), after unilateral GKT. Patients were assessed with psychological tests and acoustic voice analysis. Tremor assessment was performed with a digitising table using the Fahn-Tolosa-Marin rating scale (FTMRS). The Unified Parkinson's Disease rating scale part III (UPDRS-III) was also used in the PD group. Gait and balance was assessed using clinical tests, stabilometric platform, and treadmill. RESULTS: No side effects were observed in a two-year follow-up. There was no notable deterioration observed in the patients' psychological evaluation, speech, or assessment of gait and balance. The scores were significantly lower (p = 0.01) in parts A and B of FTMRS one year after GKT. In post hoc analysis, the scores did not differ significantly between V0 and V24. In FTMRS part C (activities of daily living), no significant change was observed. There was no significant difference in total UPDRS part III score or in score of UPDRS part III domains 3 and 4 ('tremor at rest' and 'action and postural tremor of hands') between measurements. CONCLUSIONS: UGKT may be a safe treatment modality if performed in an experienced centre. Tremor reduction may diminish over time, and UGKT did not lead to cognitive, gait or speech deterioration in a long-term observation.

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.

Limb Preference Changes after Focused-Ultrasound Thalamotomy for Tremor.

BACKGROUND: Magnetic resonance-guided focused-ultrasound (MRgFUS) thalamotomy is an effective treatment for essential and other tremors. It targets the ventrointermedius (Vim) nucleus, which is the thalamic relay in a proprioceptive pathway, and contains kinesthetic cells. Although MRgFUS thalamotomy reduces some risks associated with more invasive surgeries, it still has side effects, such as balance and gait disturbances; these may be caused by the lesion impacting proprioception. OBJECTIVES: Our aim was to quantitatively measure the effects of MRgFUS on proprioception and limb use in essential tremor patients. We hypothesized that this thalamotomy alters proprioception, because the sensorimotor Vim thalamus is lesioned. METHODS: Proprioception was measured using the Kinarm exoskeleton robot in 18 patients. Data were collected pre-operatively, and then 1 day, 3 months, and 1 year after surgery. Patients completed four tasks, assessing motor coordination and postural control, goal-directed movement and bimanual planning, position sense, and kinesthesia. RESULTS: Immediately after surgery there were changes in posture speed (indicating tremor improvement), and in bimanual hand use, with the untreated limb being preferred. However, these measures returned to pre-operative baseline over time. There were no changes in parameters related to proprioception. None of these measures correlated with lesion size or lesion-overlap with the dentato-rubro-thalamic tract. CONCLUSIONS: This is the first quantitative assessment of proprioception and limb preference following MRgFUS thalamotomy. Our results suggest that focused-ultrasound lesioning of the Vim thalamus does not degrade proprioception but alters limb preference. This change may indicate a required "relearning" in the treated limb, because the effect is transient. © 2023 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society.

A phase 1 open-label trial evaluating focused ultrasound unilateral anterior thalamotomy for focal onset epilepsy.

OBJECTIVE: Focused ultrasound ablation (FUSA) is an emerging treatment for neurological and psychiatric diseases. We describe the initial experience from a pilot, open-label, single-center clinical trial of unilateral anterior nucleus of the thalamus (ANT) FUSA in patients with treatment-refractory epilepsy. METHODS: Two adult subjects with treatment-refractory, focal onset epilepsy were recruited. The subjects received ANT FUSA using the Exablate Neuro (Insightec) system. We determined the safety and feasibility (primary outcomes), and changes in seizure frequency (secondary outcome) at 3, 6, and 12 months. Safety was assessed by the absence of side effects, that is, new onset neurological deficits or performance deterioration on neuropsychological testing. Feasibility was defined as the ability to create a lesion within the anterior nucleus. The monthly seizure frequency was compared between baseline and postthalamotomy. RESULTS: The patients tolerated the procedure well, without neurological deficits or serious adverse events. One patient experienced a decline in verbal fluency, attention/working memory, and immediate verbal memory. Seizure frequency reduced significantly in both patients; one patient was seizure-free at 12 months, and in the second patient, the frequency reduced from 90-100 seizures per month to 3-6 seizures per month. SIGNIFICANCE: This is the first known clinical trial to assess the safety, feasibility, and preliminary efficacy of ANT FUSA in adult patients with treatment-refractory focal onset epilepsy.

Bilateral Radiofrequency Ventral Intermediate Thalamotomy for Essential Tremor.

INTRODUCTION: With the advent of MR-guided focused ultrasound, the importance of the efficacy and safety of bilateral ventral intermediate (Vim) thalamotomy for essential tremor (ET) has increased. However, reports on bilateral Vim thalamotomy for ET remain scarce. METHODS: To review the results and complications of bilateral Vim thalamotomy for the treatment of ET in the upper extremities, we retrospectively analyzed the patients with ET who underwent bilateral Vim thalamotomy with radiofrequency (RF) thermal coagulation. As bilateral simultaneous thalamotomy can cause surgical complications, thalamotomy was performed in stages. The interval between the first and second thalamotomies was 21.3 ± 14.7 months. We evaluated the efficacy using the Clinical Rating Scale for Tremor (CRST) before and after the first and second treatments, respectively. We also evaluated the complications before and after the first and second treatments, respectively. Moreover, we assessed the adverse events. RESULTS: Seventeen patients were included in the study. The mean follow-up period following the second thalamotomy was 29.3 ± 15.0 months. The CRST part A + B scores were 34.9 ± 9.7, 20.8 ± 7.0, and 7.4 ± 6.8 before, following the first (40.4% improvement, p < 0.0001) and second thalamotomies (78.6% improvement, p < 0.0001), respectively. Nine patients presented with prolonged adverse events, including dysarthria, dysgeusia, dysphagia, tongue numbness, unsteady gait, and postural instability at the last available evaluation. All adverse events were mild and did not interfere with the patient's daily activities. DISCUSSION/CONCLUSIONS: Bilateral Vim thalamotomy with RF thermal coagulation was an effective treatment for ET in both upper extremities. Despite most possible complications being mild, additional studies with a larger sample size are required to ensure patient safety.

Stereotactic Staged Asymmetric Bilateral Radiofrequency Lesioning for Parkinson's Disease.

INTRODUCTION: Parkinson's disease (PD) is one of the most common neurodegenerative progressive disorders. Despite the dominance of neurostimulation technology, stereotactic lesioning operations play a significant role in the treatment of PD. The aim of the study was to evaluate the effectiveness and safety of staged bilateral asymmetric radiofrequency (RF) stereotactic lesioning in a highly selected group of PD patients. MATERIAL AND METHODS: A retrospective review of 418 consecutive patients undergoing stereotactic ablation for advanced PD at our institution revealed 28 patients who underwent staged asymmetric bilateral ablation. In this subset, after initial RF thalamotomy, contralateral pallidotomy was performed in 16 (57.1%) patients (group Vim-GPi), and contralateral lesion of the subthalamic nucleus (STN) was performed in 12 (32.9%) patients (group Vim-STN). The mean duration of disease before the first surgery was 9.9 ± 0.8 years. The mean interval between the two operations was 3.5 ± 0.4 years (range, 1-10 years); in the Vim-GPi group, it was 3.1 ± 0.4 years; and in the Vim-STN group, it was 4.3 ± 0.1 years. After the second operation, the long-term follow-up lasted from 1 to 8 years (mean 4.8 ± 0.5 years). All patients were evaluated 1 year after the second operation. RESULTS: One year after staged bilateral lesioning, the mean tremor score improved from baseline, prior to the first operation, from 19.8 to 3.8 (improvement of 81%), the overall mean rigidity score improved from 11.0 to 3.7 (improvement of 66%), and hypokinesia improved from 14.8 to 8.9 (improvement of 40%). One year after staged bilateral lesioning, the total UPDRS score improved in the Vim-GPi group by 47% in the OFF and 45.9% in the ON states. In the Vim-STN group, the total UPDRS score improved from baseline, prior to the first operation, by 44.8% in the OFF and 51.6% in the ON states. Overall, levodopa dose was reduced by 43.4%. Neurological complications were observed in 4 (14.3%) cases; among them, 1 (3.6%) patient had permanent events related to local ischemia after pallidotomy. CONCLUSION: Staged asymmetric bilateral stereotactic RF lesioning can be a safe and effective method in highly selected patients with advanced PD, particularly where deep brain stimulation is not available or desirable. Careful identification and selection of patients for ablative surgery allow achieving optimal results in the treatment of PD with bilateral symptoms.

Hemorrhagic Safety of Magnetic Resonance-Guided Focused Ultrasound Thalamotomy for Tremor without Interruption of Antiplatelet or Anticoagulant Therapy.

INTRODUCTION: Magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy is an incision-less ablative technique used to treat medically refractory tremor. Although intracerebral hemorrhage has not been reported with MRgFUS thalamotomy for the treatment of movement disorders, clinicians commonly interrupt active blood thinning medications prior to the procedure or offer gamma knife radiosurgery instead. However, MRgFUS uses focal thermoablation, and bleeding risk is likely minimal. This study aimed to evaluate the safety of MRgFUS thalamotomy in patients with essential tremor (ET) and tremor-dominant Parkinson's disease (PD) without interrupting anticoagulant or antiplatelet therapies. METHODS: This was a single-center retrospective case series of all patients with ET or PD undergoing MRgFUS from February 2019 through December 2022 (n = 96). Demographic variables and medications taken at the time of surgery were obtained. Our primary outcome was the type and frequency of hemorrhagic complications noted on the operative report or postoperative imaging. RESULTS: The mean age of patients was 74.2 years, and 26% were female. Forty patients were taking ≥1 antiplatelet or anticoagulant medications. No patient actively taking anticoagulant or antiplatelet therapies had a hemorrhagic complication during or <48 h after the procedure. CONCLUSION: The frequency of intra- or postoperative complications from MRgFUS was not higher in patients actively taking anticoagulant or antiplatelet therapies relative to those who were not. Our findings suggest that MRgFUS thalamotomy does not necessitate interrupting anticoagulant or antiplatelet therapies. However, given the limited number of patients actively taking these therapies in our cohort (n = 40), additional testing in large, prospective studies should be conducted to further establish safety.

Gait Function after High-Intensity Focused Ultrasound Thalamotomy for Essential Tremor: Searching for Technique Optimization.

INTRODUCTION: Essential tremor (ET) is one of the most prevalent movement disorders in adults and may be highly disabling for some. Magnetic resonance image-guided high-intensity focused ultrasound (MRIgFUS) has been shown to control tremor efficaciously and with acceptable risk. To date, paresthesia and ataxia are the most common adverse effects (AE). Nevertheless, the impact of MRIgFUS thalamotomy on balance is not well established. METHODS: Thirty-two patients underwent MRIgFUS for ET and completed 6 months of follow-up. Tremor severity and functional disability were assessed using the Essential Tremor Rating Scale and the Quality of Life in Essential Tremor Questionnaire. The Berg Balance Scale (BBS) was applied to objectively measure balance status. RESULTS: All treatments were successful. The sonication target was 1-2 mm above the depth of the intercommissural line. Procedures lasted less the 2 h, with an average of 8 sonications per patient. Twenty-four patients were included in the tremor analysis. The hand tremor score was improved by 76% after 6 months of follow-up and 87% of patients self-reported marked improvement (≥75%). Disability scores showed marked improvement (78%), leading to a significant improvement in quality of life. At the final follow-up, 48% of the patients reported no side effects. When present, AE were generally transient and were considered mild in 96% of affected patients. Paresthesia and subjective feeling of unsteadiness were the most common persistent complaints (23% and 20%, respectively). Regarding objective ataxia, BBS scores remained stable throughout follow-up for most patients. Only 2 patients suffered a mild worsening of balance although no patients experienced moderate or severe ataxia. CONCLUSIONS: Subjective feeling of unsteadiness is one of the most frequent AE after MRIgFUS, although objective ataxia is infrequent and mild. Selecting the most appropriate lesion location and procedural parameters should increase treatment benefits while reducing side effects.

Focused Ultrasound Thalamotomy: Correlation of Postoperative Imaging with Neuropathological Findings.

Magnetic resonance-guided high-intensity focused ultrasound (MRgFUS) is a rapidly developing technique used for tremor relief in tremor-predominant Parkinson's disease (PD) and essential tremor that has demonstrated successful results. Here, we describe the neuropathological findings in a woman who died from a fall 10 days after successful MRgFUS for tremor-predominant PD. Histological analysis demonstrates the characteristic early postoperative MRI findings including 3 distinct zones on T2-weighted imaging: (1) a hypointense core, (2) a hyperintense region with hypointense rim, and (3) a slightly hyperintense, poorly marginated surrounding area. Histopathological analyses also demonstrate the suspected cellular processes composing each of these regions including central hemorrhagic necrosis with surrounding cytotoxic edema and a rim of mostly unaffected vasogenic edema with some reactive and reparative processes. Overall, this case demonstrates the correlation of postoperative imaging findings with the subacute neuropathological findings after MRgFUS for PD.

Improvement in Intraoperative Image Quality in Transcranial Magnetic Resonance-Guided Focused Ultrasound Surgery Using Transmitter Gain Adjustment.

INTRODUCTION: Transcranial magnetic resonance-guided focused ultrasound surgery (TcMRgFUS) has the advantage of allowing immediate evaluation of therapeutic effects after each sonication and intraoperative magnetic resonance imaging (MRI) to visualize the lesion. When the image shows that the lesion has missed the planned target and the therapeutic effects are insufficient, the target of the subsequent ablation can be finely adjusted based on the image. The precision of this adjustment is determined by the image quality. However, the current intraoperative image quality with a 3.0T MRI system is insufficient for precisely detecting the lesion. Thus, we developed and validated a method for improving intraoperative image quality. METHODS: Because intraoperative image quality is affected by transmitter gain (TG), we acquired T2-weighted images (T2WIs) with two types of TG: the automatically adjusted TG (auto TG) and the manually adjusted TG (manual TG). To evaluate the character of images with 2 TGs, the actual flip angle (FA), the image uniformity, and the signal-to-noise ratio (SNR) were measured using a phantom. Then, to assess the quality of intraoperative images, T2WIs with both TGs were acquired during TcMRgFUS for 5 patients. The contrast-to-noise ratio (CNR) of the lesion was retrospectively estimated. RESULTS: The images of the phantom with the auto TG showed substantial variations between the preset and actual FAs (p < 0.01), whereas on the images with the manual TG, there were no variations between the two FAs (p > 0.05). The total image uniformity was considerably lower with the manual TG than with the auto TG (p < 0.01), indicating that the image's signal values with the manual TG were more uniform. The manual TG produced significantly higher SNRs than the auto TG (p < 0.01). In the clinical study, the lesions were clearly detected in intraoperative images with the manual TG, but they were difficult to identify in images with the auto TG. The CNR of lesions in images with manual TG was considerably higher than in images with auto TG (p < 0.01). CONCLUSION: Regarding intraoperative T2WIs using a 3.0T MRI system during TcMRgFUS, the manual TG method improved image quality and delineated the ablative lesion more clearly than the current method with auto TG.

MRgFUS thalamotomy for the treatment of tremor: evaluation of learning curve and operator's experience impact on the procedural and clinical outcome.

BACKGROUND: MRgFUS Vim ablation is increasingly used for the treatment of tremor in ET e PD patients but there is little published research on the importance of operator experience in this procedure. This study aims to evaluate the learning curve and the influence of the operator experience on the procedural and clinical outcomes. METHODS: We retrospectively evaluated 90 patients (38 ET, 52 PD) submitted to MRgFUS unilateral thalamotomy in the period between February 2018 and July 2020. Clinical endpoints, procedural times, and technical parameters were recorded in all procedures. Based on the time of treatment, patients were divided into three groups of 30 units each, comparing all variables between each time period group. RESULTS: In Group A, the average patient preparation time was 120.6 min, the treatment time was 105.2 min, the number of was sonications 14.1, and the mean target shifts 3.1. In Group B, the mean preparation time was 105.5 min, the treatment time was 89.5 min, the number of sonications was 13.2, and the target shifts 3.0. Group C showed inferior values of preparation time (101.9 min), treatment time (71.7 min), numbers of sonications (10.6), and shifts (1.7). Thalamotomy-related complications occurred in 9 patients of Group A, 2 of Group B, and 5 of Group C. Tremor relapse occurred in 7 patients of Group A, 3 of Group B, and 2 of Group C. The days of hospitalization were comparable in the three groups. CONCLUSIONS: The operators experience is associated with the improvement of clinical and procedural outcome in MRgFUS thalatomy for the treatment of ET and PD tremor.

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.

Cavitation with low-energy sonication during focused ultrasound thalamotomy for a patient with tremor-dominant Parkinson's disease: a potential risk.

We report a patient with tremor-dominant Parkinson's disease who had a mild cavitation bioeffect during magnetic resonance-guided focused ultrasound thalamotomy. During the aligning phase with low-energy sonication, cavitation caused mild dysarthria and paresthesia, prompting treatment cessation. At the same time, tremor and rigidity improved. MRI revealed extensive high-intensity lesions in the thalamus 1 day after the procedure followed by steroid infusion, which resulted in resolution of adverse events. Tremor and rigidity improved 1.5 years after the procedure. Although cavitation can relieve tremors and rigidity, it should be carefully monitored due to potential permanent adverse events by unpredictable and unknown behaviors.

Deep brain stimulation for Parkinson's disease.

Parkinson's disease (PD) is a progressive neurodegenerative illness with both motor and nonmotor symptoms. Deep brain stimulation (DBS) is an established safe neurosurgical symptomatic therapy for eligible patients with advanced disease in whom medical treatment fails to provide adequate symptom control and good quality of life, or in whom dopaminergic medications induce severe side effects such as dyskinesias. DBS can be tailored to the patient's symptoms and targeted to various nodes along the basal ganglia-thalamus circuitry, which mediates the various symptoms of the illness; DBS in the thalamus is most efficient for tremors, and DBS in the pallidum most efficient for rigidity and dyskinesias, whereas DBS in the subthalamic nucleus (STN) can treat both tremors, akinesia, rigidity and dyskinesias, and allows for decrease in doses of medications even in patients with advanced stages of the disease, which makes it the preferred target for DBS. However, DBS in the STN assumes that the patient is not too old, with no cognitive decline or relevant depression, and does not exhibit severe and medically resistant axial symptoms such as balance and gait disturbances, and falls. Dysarthria is the most common side effect of DBS, regardless of the brain target. DBS has a long-lasting effect on appendicular symptoms, but with progression of disease, nondopaminergic axial features become less responsive to DBS. DBS for PD is highly specialised; to enable adequate selection and follow-up of patients, DBS requires dedicated multidisciplinary teams of movement disorder neurologists, functional neurosurgeons, specialised DBS nurses and neuropsychologists.

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.

Lesion location and lesion creation affect outcomes after focused ultrasound thalamotomy.

MRI-guided focused ultrasound thalamotomy has been shown to be an effective treatment for medication refractory essential tremor. Here, we report a clinical-radiological analysis of 123 cases of MRI-guided focused ultrasound thalamotomy, and explore the relationships between treatment parameters, lesion characteristics and outcomes. All patients undergoing focused ultrasound thalamotomy by a single surgeon were included. The procedure was performed as previously described, and patients were followed for up to 1 year. MRI was performed 24 h post-treatment, and lesion locations and volumes were calculated. We retrospectively evaluated 118 essential tremor patients and five tremor-dominant Parkinson's disease patients who underwent thalamotomy. At 24 h post-procedure, tremor abated completely in the treated hand in 81 essential tremor patients. Imbalance, sensory disturbances and dysarthria were the most frequent acute adverse events. Patients with any adverse event had significantly larger lesions, while inferolateral lesion margins were associated with a higher incidence of motor-related adverse events. Twenty-three lesions were identified with irregular tails, often extending into the internal capsule; 22 of these patients experienced at least one adverse event. Treatment parameters and lesion characteristics changed with increasing surgeon experience. In later cases, treatments used higher maximum power (normalized to skull density ratio), accelerated more quickly to high power, and delivered energy over fewer sonications. Larger lesions were correlated with a rapid rise in both power delivery and temperature, while increased oedema was associated with rapid rise in temperature and the maximum power delivered. Total energy and total power did not significantly affect lesion size. A support vector regression was trained to predict lesion size and confirmed the most valuable predictors of increased lesion size as higher maximum power, rapid rise to high-power delivery, and rapid rise to high tissue temperatures. These findings may relate to a decrease in the energy efficiency of the treatment, potentially due to changes in acoustic properties of skull and tissue at higher powers and temperatures. We report the largest single surgeon series of focused ultrasound thalamotomy to date, demonstrating tremor relief and adverse events consistent with reported literature. Lesion location and volume impacted adverse events, and an irregular lesion tail was strongly associated with adverse events. High-power delivery early in the treatment course, rapid temperature rise, and maximum power were dominant predictors of lesion volume, while total power, total energy, maximum energy and maximum temperature did not improve prediction of lesion volume. These findings have critical implications for treatment planning in future patients.