Staged Bilateral MRI-Guided Focused Ultrasound Subthalamotomy for Parkinson Disease.

Importance: Unilateral magnetic resonance imaging (MRI)-guided focused ultrasound subthalamotomy (FUS-STN) improves cardinal motor features among patients with asymmetrical Parkinson disease (PD). The feasibility of bilateral FUS-STN is as yet unexplored. Objective: To assess the safety and effectiveness of staged bilateral FUS-STN to treat PD. Design, Setting, and Participants: This prospective, open-label, case series study was conducted between June 18, 2019, and November 7, 2023, at HM-CINAC, Puerta del Sur University Hospital, Madrid, Spain, and included 6 patients with PD who had been treated with unilateral FUS-STN contralateral to their most affected body side and whose parkinsonism on the untreated side had progressed and was not optimally controlled with medication. Intervention: Staged bilateral FUS-STN. Main Outcomes and Measures: Primary outcomes were assessed 6 months after the second treatment and included safety (incidence and severity of adverse events after second treatment) and effectiveness in terms of motor change (measured with the Movement Disorders Society Unified Parkinson's Disease Rating Scale part III [MDS-UPDRS III]) in the off-medication state (ie, after at least 12 hours of antiparkinsonian drug withdrawal) compared with baseline (ie, prior to the first side ablation). Secondary outcomes included motor change in patients in the on-medication state (ie, after usual antiparkinsonian medication intake), motor complications (measured with the MDS-UPDRS IV), daily living activities (measured with the MDS-UPDRS I-II), quality of life (measured with the 39-item Parkinson's Disease Questionnaire), change in dopaminergic treatment, patient's global impression of change (measured with the Global Impression of Change [PGI-C] scale), and long-term (24-month) follow-up. Results: Of 45 patients previously treated with unilateral FUS-STN, 7 were lost to follow-up, and 4 were excluded due to adverse events. Of the remaining 34 patients, 6 (median age at first FUS-STN, 52.6 years [IQR, 49.0-57.3 years]; 3 women [50%]) experienced progression of parkinsonism on the untreated body side and were included. At the time of the first FUS-STN, patients' median duration of disease was 5.7 years (IQR, 4.7-7.3 years). The median time between procedures was 3.2 years (IQR, 1.9-3.5 years). After the second FUS-STN, 4 patients presented with contralateral choreic dyskinesia, which resolved by 3 months. Four patients developed speech disturbances, which gradually improved but remained in a mild form for 2 patients at 6 months; 1 patient experienced mild imbalance and dysphagia during the first week after treatment, which subsided by 3 months. No behavioral or cognitive disturbances were found on neuropsychological testing. For patients in the off-medication state, MDS-UPDRS III scores improved by 52.6% between baseline and 6 months after the second FUS-STN (from 37.5 [IQR, 34.2-40.0] to 20.5 [IQR, 8.7-24.0]; median difference, 23.0 [95% CI, 7.0-33.7]; P = .03). The second treated side improved by 64.3% (MDS-UPDRS III score, 17.0 [IQR, 16.0-19.5] prior to the second treatment vs 5.5 [IQR, 3.0-10.2]; median difference, 9.5 [95% CI, 3.2-17.7]; P = .02). After the second procedure, all self-reported PGI-C scores were positive. Conclusions: Findings of this pilot study suggest that staged bilateral FUS-STN was safe and effective for the treatment of PD, although mild but persistent speech-related adverse events were observed among a small number of patients.

Unilateral focused ultrasound subthalamotomy in early Parkinson's disease: a pilot study.

BACKGROUND: Unilateral focused ultrasound subthalamotomy (FUS-STN) improves motor features of Parkinson's disease (PD) in moderately advanced patients. The less invasive nature of FUS makes its early application in PD feasible. We aim to assess the safety and efficacy of unilateral FUS-STN in patients with PD of less than 5 years from diagnosis (early PD). METHODS: Prospective, open-label study. Eligible patients with early PD had highly asymmetrical cardinal features. The primary outcome was safety, defined as treatment-related adverse events at 6 months. Secondary outcomes included efficacy, assessed as motor improvement in the Movement Disorders Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS), motor fluctuations, non-motor symptoms, daily living activities, quality of life, medication and patients' impression of change. RESULTS: Twelve patients with PD (median age 52.0 (IQR 49.8-55.3) years, median time from diagnosis 3.0 (2.1-3.9) years) underwent unilateral FUS-STN. Within 2 weeks after treatment, five patients developed dyskinesia on the treated side, all resolved after levodopa dose adjustment. One patient developed mild contralateral motor weakness which fully resolved in 4 weeks. One patient developed dystonic foot and another hand and foot dystonia. The latter impaired gait and became functionally disabling initially. Both cases were well controlled with botulinum toxin injections. The off-medication motor MDS-UPDRS score for the treated side improved at 12 months by 68.7% (from 14.5 to 4.0, p=0.002), and the total motor MDS-UPDRS improved by 49.0% (from 26.5 to 13.0, p=0.002). Eleven patients (92%) reported global improvement 12 months after treatment. CONCLUSION: Unilateral FUS-STN may be safe and effective to treat motor manifestations in patients with early PD. A larger confirmatory trial is warranted. TRIAL REGISTRATION NUMBER: NCT04692116.

Prospective Long-term Follow-up of Focused Ultrasound Unilateral Subthalamotomy for Parkinson Disease.

BACKGROUND AND OBJECTIVES: Unilateral magnetic resonance-guided focused ultrasound subthalamotomy (FUS-STN) has been shown to improve the cardinal motor features of Parkinson disease (PD). Whether this effect is sustained is not known. This study aims to report the long-term outcome of patients with PD treated with unilateral FUS-STN. METHODS: We conducted a prospective open-label study of patients with asymmetrical PD who underwent unilateral FUS-STN. All patients were evaluated up to 36 months after treatment. The primary outcome was the difference from baseline to 36 months after FUS-STN in the score of the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) motor part (III) for the treated hemibody in the off-medication state. The safety outcome included all adverse events occurring during follow-up. Secondary outcomes were the change in the MDS-UPDRS III score on-medication; subscores of rigidity, bradykinesia, tremor, and axial features; total MDS-UPDRS III; and the MDS-UPDRS part IV. Functional disability and quality of life were assessed using the MDS-UPDRS II and the PDQ39, respectively. Patient impression of change and satisfaction with the treatment were self-assessed. The Wilcoxon signed-rank test with subsequent Bonferroni's correction was used for data analysis. RESULTS: Thirty-two patients with PD were evaluated at 36 months after treatment. The mean (±SD) age at baseline was 56.0 ± 10.1 years, with a mean disease duration of 6.8 ± 2.8 years. The MDS-UPDRS III score for the treated hemibody off-medication was improved by 52.3% from baseline to 3 years (score reduction from 19.0 ± 3.2 to 8.9 ± 3.3, 95% CI 8.7 to 11.6, p < 0.001), and all specific motor features were improved from baseline. No disabling or delayed adverse events were reported. The total MDS-UPDRS III off-medication score was 22.9% lower at 3 years than before treatment (36.8 ± 7.4 vs 27.4 ± 6.2, 95% CI 6.0 to 11.5, p < 0.001). The MDS-UPDRS II, IV, and PDQ39 scores and levodopa dose were equivalent to those at baseline. DISCUSSION: The benefit of unilateral FUS-STN on PD motor features is sustained in the long term. FUS-STN contributes to better clinical control over several years of evolution. NCT02912871/03454425. CLASSIFICATION OF EVIDENCE: This study provides Class IV evidence on the utility of focused ultrasound unilateral subthalamotomy in the treatment of people with Parkinson disease.

Validation of the OPTIMIPARK Questionnaire: A Tool to Optimize Treatment in Parkinson's Disease.

Background: Dopamine replacement therapy reduces most motor and nonmotor features of Parkinson's disease. However, with disease progression, adjustments of dopaminergics and the application of advanced therapies must be considered. Objectives: To validate the OPTIMIPARK questionnaire as a tool to help clinicians make therapeutic decisions on patients treated with levodopa. Methods: We tested a questionnaire including 9 items encompassing motor and nonmotor signs, complications, and disability in a multicenter, observational, cross-sectional study. A neurologist (neurologist 1 [N1]) assessed patients according to regular clinical practice and blinded to the OPTIMIPARK questionnaire score. Therapeutic decisions were classified as "no changes," "adjustment of conventional treatment," and "advanced therapy indicated." External neurologists (neurologist 3 [N3] and neurologist 4 [N4]), who only knew the patient age, years of disease, and current treatment, made their therapeutic decisions based on the OPTIMIPARK score. Concordance between the criterion of the N1 versus the OPTIMIPARK-based N3-N4 consensus was analyzed applying weighted κ. The area under Receiving Operating Characteristic (ROC) curves was calculated for OPTIMIPARK scores. Results: A total of 113 patients with Parkinson's disease were included. The OPTIMIPARK-based decision led to a higher proportion of patients requiring therapeutic modification than N1 assessment (74% vs. 60%; P = 0.002). Concordance between the N1 and N3-N4 decisions was moderate, whereas interobserver agreement among N3 and N4 was high. Area Under the Curve(AUC) values of 0.83 and 0.82 were found for "no changes" and "advanced therapy indicated" decisions by the N1 neurologist. Conclusions: OPTIMIPARK might be more sensitive than regular clinical practice in suggesting the need for a therapeutic change. Furthermore, the low and high scores identify with high accuracy well-adjusted patients and candidates for advanced therapy, respectively.

Neuroimaging signatures predicting motor improvement to focused ultrasound subthalamotomy in Parkinson's disease.

Subthalamotomy using transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) is a novel and promising treatment for Parkinson's Disease (PD). In this study, we investigate if baseline brain imaging features can be early predictors of tcMRgFUS-subthalamotomy efficacy, as well as which are the post-treatment brain changes associated with the clinical outcomes. Towards this aim, functional and structural neuroimaging and extensive clinical data from thirty-five PD patients enrolled in a double-blind tcMRgFUS-subthalamotomy clinical trial were analyzed. A multivariate cross-correlation analysis revealed that the baseline multimodal imaging data significantly explain (P < 0.005, FWE-corrected) the inter-individual variability in response to treatment. Most predictive features at baseline included neural fluctuations in distributed cortical regions and structural integrity in the putamen and parietal regions. Additionally, a similar multivariate analysis showed that the population variance in clinical improvements is significantly explained (P < 0.001, FWE-corrected) by a distributed network of concurrent functional and structural brain changes in frontotemporal, parietal, occipital, and cerebellar regions, as opposed to local changes in very specific brain regions. Overall, our findings reveal specific quantitative brain signatures highly predictive of tcMRgFUS-subthalamotomy responsiveness in PD. The unanticipated weight of a cortical-subcortical-cerebellar subnetwork in defining clinical outcome extends the current biological understanding of the mechanisms associated with clinical benefits.

Lesion 3D modeling in transcranial MR-guided focused ultrasound thalamotomy.

Transcranial magnetic resonance-guided focused ultrasound (tMRgFUS) allows to perform incisionless thermoablation of deep brain structures. This feature makes it a very useful tool for the treatment of multiple neurological and psychiatric disorders. Currently, feedback of the thermoablation process is based on peak temperature readings assessed on real-time two-dimensional MRI thermometry. However, an accurate methodology relating thermal dosimetry with three-dimensional topography and temporal evolution of the lesion is still to be defined, thus hurdling the establishment of well-defined, evidence-based criteria to perform safe and effective treatments. In here we propose threshold-based thermoablation models to predict the volumetric topography of the lesion (whole lesion and necrotic core) in the short-to-mid-term based on thermal dosimetry estimated from intra-treatment MRI thermometry. To define and validate our models we retrospectively analyzed the data of sixty-three tMRgFUS thalamotomies for treating tremor. We used intra-treatment MRI thermometry to estimate whole-treatment three-dimensional thermal dose maps, defined either as peak temperature reached (Tmax) or thermal isoeffective dose (TID). Those maps were thresholded to find the dosimetric level that maximize the agreement (Sorensen-Dice coefficient - SDc) with the boundaries of the whole lesion and its core, assessed on T2w images 1-day (post-24h) and 3-months (post-3M) after treatment. Best predictions were achieved for the whole lesion at post-24h (SDc = 0.71), with Tmax /TID over 50.0 °C/90.5 CEM43. The core at post-24h and whole lesion at post-3M lesions reported a similar behavior in terms of shape accuracy (SDc ~0.35), and thermal dose thresholds ~55 °C/4100.0 CEM43. Finally, the optimal levels for post-3M core lesions were 55.5 °C/5800.0 CEM43 (SDc = 0.21). These thermoablation models could contribute to the real-time decision-making process and improve the outcome of tMRgFUS interventions both in terms of safety and efficacy.

Bilateral staged magnetic resonance-guided focused ultrasound thalamotomy for the treatment of essential tremor: a case series study.

BACKGROUND: Unilateral magnetic resonance-guided focused ultrasound (FUS) thalamotomy is efficacious for the treatment of medically refractory essential tremor (ET). Viability of bilateral FUS ablation is unexplored. METHODS: Patients diagnosed with medically refractory ET and previously treated with unilateral FUS thalamotomy at least 5 months before underwent bilateral treatment. The timepoints were baseline (before first thalamotomy) and FUS1 and FUS2 (4 weeks before and 6 months after second thalamotomy, respectively). The primary endpoint was safety. Efficacy was assessed through the Clinical Rating Scale for Tremor (CRST), which includes subscales for tremor examination (part A), task performance (part B) and tremor-related disability (part C). RESULTS: Nine patients were treated. No permanent adverse events were registered. Six patients presented mild gait instability and one dysarthria, all resolving within the first few weeks. Three patients reported perioral hypoesthesia, resolving in one case. Total CRST score improved by 71% from baseline to FUS2 (from 52.3±12 to 15.5±9.4, p<0.001), conveying a 67% reduction in bilateral upper limb A+B (from 32.3±7.8 to 10.8±7.3, p=0.001). Part C decreased by 81% (from 16.4±3.6 to 3.1±2.9, p<0.001). Reduction in head and voice tremor was 66% (from 1.2±0.44 to 0.4±0.54, p=0.01) and 45% (from 1.8±1.1 to 1±0.8, p=0.02), respectively. CONCLUSION: Bilateral staged FUS thalamotomy for ET is feasible and might be safe and effective. Voice and head tremor might also improve. A controlled study is warranted.

Present and future of subthalamotomy in the management of Parkinson´s disease: a systematic review.

Introduction: The subthalamic nucleus (STN) is known to be involved in the pathophysiology of Parkinson´s disease and by reducing its abnormal activity, normal output of basal ganglia can be restored along with improvement in PD cardinal motor features. Deep brain stimulation of the STN is currently the main surgical procedure for PD with motor complications, but lesioning can be an alternative.Areas covered: Here, the authors systematically review the current evidence regarding subthalamotomy both with radiofrequency and, more recently, with focused ultrasound (FUS) for the treatment of PD.Expert opinion: Unilateral subthalamotomy for the treatment of PD motor features can be considered a viable option in asymmetric patients, particularly with FUS which allows a minimally invasive safe and effective ablation of the STN. Risk of inducing dyskinesia (i.e., hemichorea/ballism) may be strikingly reduced when lesions enlarge dorsally to impinge on pallidothalamic fibers.

Estudio piloto de una nueva herramienta para optimizar el tratamiento dopaminérgico en la enfermedad de Parkinson: el cuestionario OPTIMIPARK / Pilot study of a new tool to optimise dopaminergic treatment in Parkinson's disease: the OPTIMIPARK questionnaire

INTRODUCCIÓN: La terapia dopaminérgica es eficaz en la enfermedad de Parkinson (EP), si bien debe ajustarse conforme progresa la neurodegeneración. OBJETIVOS: Desarrollar un cuestionario (OPTIMIPARK) para valorar el estado dopaminérgico del paciente y ayudar al clínico en el ajuste del tratamiento. PACIENTES Y MÉTODOS: La versión preliminar, autoadministrada, de OPTIMIPARK incluye nueve ítems que tienen en cuenta complicaciones motoras y no motoras, así como la discapacidad. Cada ítem se valora de 0 a 2, y se obtiene una puntuación global de 0 a 18. Treinta pacientes contestaron el cuestionario OPTIMIPARK y un cuestionario ad hoc sobre éste en un estudio piloto unicéntrico y observacional. Se analizaron la viabilidad, la aceptabilidad y la concordancia preliminar con los criterios clínicos. RESULTADOS: Treinta pacientes con EP (68,5 ± 7,5 años; rango: 43-80 años) en estadio de Hoehn & Yahr I-III completaron el OPTIMIPARK (media de la puntuación total: 6,7 ± 4; rango: 0-14) y el cuestionario ad hoc. Las decisiones clínicas se clasificaron como: sin cambios, ajustes en el tratamiento convencional y terapia quirúrgica o de infusión continua. Las puntuaciones totales de OPTIMIPARK (media ± desviación estándar) para cada opción fueron: 1,4 ± 1 (rango: 0-3); 7 ± 2,8 (rango: 2-11); y 10,8 ± 1,8 (rango: 9-14). El punto de corte 3/4 clasificó al 95,5% de los pacientes sin cambios frente a ajustes del tratamiento convencional, y el corte 9/10 discriminó al 78,3% de los pacientes de ajuste del tratamiento convencional frente a terapia quirúrgica o de infusión continua, con concordancia (coeficientes kappa y Lin) de 0,81. CONCLUSIONES: Pendiente del estudio de validación, OPTIMIPARK puede ser un cuestionario viable y útil para la toma de decisiones clínicas en el ajuste terapéutico de pacientes con EP y la identificación de candidatos para terapias avanzadas

INTRODUCTION: Dopaminergic therapy is effective in Parkinson's disease (PD), but should be adjusted as neurodegeneration progresses. AIMS: The aim of this study was to develop a questionnaire (OPTIMIPARK) to assess the patient's dopaminergic status and assist the clinician in adjusting treatment. PATIENTS AND METHODS: The preliminary, self-administered version of OPTIMIPARK includes nine items that take into account motor and non-motor complications as well as disability. Each item is given a score between 0 and 2, and an overall score from 0 to 18 is obtained. Thirty patients completed the OPTIMIPARK questionnaire and an ad hoc questionnaire about it in a single-centre, observational pilot study. Feasibility, acceptability and preliminary agreement with clinical criteria were analysed. RESULTS: Thirty patients with PD (68.5 ± 7.5 years; range: 43-80 years) in Hoehn & Yahr stage I-III completed OPTIMIPARK (mean total score: 6.7 ± 4; range: 0-14) and the ad hoc questionnaire. Clinical decisions were classified as: 'no change', 'adjustments to conventional treatment' and 'surgical or continuous infusion therapy'. The total OPTIMIPARK scores (mean ± standard deviation) for each option were: 1.4 ± 1 (range: 0-3); 7 ± 2.8 (range: 2-11); and 10.8 ± 1.8 (range: 9-14). The 3/4 cut-off point classified 95.5% of patients as 'no change' versus 'adjustment to conventional treatment', and the 9/10 cut-off point discriminated 78.3% of patients from 'adjustment to conventional treatment' versus 'surgical or continuous infusion therapy', with a concordance (kappa and Lin coefficients) of 0.81. CONCLUSIONS: Although still pending a validation study, OPTIMIPARK may be a viable and useful questionnaire for clinical decision-making in the therapeutic adjustment of PD patients and the identification of candidates for advanced therapies

Randomized Trial of Focused Ultrasound Subthalamotomy for Parkinson's Disease.

BACKGROUND: The subthalamic nucleus is the preferred neurosurgical target for deep-brain stimulation to treat cardinal motor features of Parkinson's disease. Focused ultrasound is an imaging-guided method for creating therapeutic lesions in deep-brain structures, including the subthalamic nucleus. METHODS: We randomly assigned, in a 2:1 ratio, patients with markedly asymmetric Parkinson's disease who had motor signs not fully controlled by medication or who were ineligible for deep-brain stimulation surgery to undergo focused ultrasound subthalamotomy on the side opposite their main motor signs or a sham procedure. The primary efficacy outcome was the between-group difference in the change from baseline to 4 months in the Movement Disorder Society-Unified Parkinson's Disease Rating Scale (MDS-UPDRS) motor score (i.e., part III) for the more affected body side (range, 0 to 44, with higher scores indicating worse parkinsonism) in the off-medication state. The primary safety outcome (procedure-related complications) was assessed at 4 months. RESULTS: Among 40 enrolled patients, 27 were assigned to focused ultrasound subthalamotomy (active treatment) and 13 to the sham procedure (control). The mean MDS-UPDRS III score for the more affected side decreased from 19.9 at baseline to 9.9 at 4 months in the active-treatment group (least-squares mean difference, 9.8 points; 95% confidence interval [CI], 8.6 to 11.1) and from 18.7 to 17.1 in the control group (least-squares mean difference, 1.7 points; 95% CI, 0.0 to 3.5); the between-group difference was 8.1 points (95% CI, 6.0 to 10.3; P<0.001). Adverse events in the active-treatment group were dyskinesia in the off-medication state in 6 patients and in the on-medication state in 6, which persisted in 3 and 1, respectively, at 4 months; weakness on the treated side in 5 patients, which persisted in 2 at 4 months; speech disturbance in 15 patients, which persisted in 3 at 4 months; facial weakness in 3 patients, which persisted in 1 at 4 months; and gait disturbance in 13 patients, which persisted in 2 at 4 months. In 6 patients in the active-treatment group, some of these deficits were present at 12 months. CONCLUSIONS: Focused ultrasound subthalamotomy in one hemisphere improved motor features of Parkinson's disease in selected patients with asymmetric signs. Adverse events included speech and gait disturbances, weakness on the treated side, and dyskinesia. (Funded by Insightec and others; ClinicalTrials.gov number, NCT03454425.).

Cortical disinhibition in Parkinson's disease.

In Parkinson's disease, striatal dopamine depletion produces profound alterations in the neural activity of the cortico-basal ganglia motor loop, leading to dysfunctional motor output and parkinsonism. A key regulator of motor output is the balance between excitation and inhibition in the primary motor cortex, which can be assessed in humans with transcranial magnetic stimulation techniques. Despite decades of research, the functional state of cortical inhibition in Parkinson's disease remains uncertain. Towards resolving this issue, we applied paired-pulse transcranial magnetic stimulation protocols in 166 patients with Parkinson's disease (57 levodopa-naïve, 50 non-dyskinetic, 59 dyskinetic) and 40 healthy controls (age-matched with the levodopa-naïve group). All patients were studied OFF medication. All analyses were performed with fully automatic procedures to avoid confirmation bias, and we systematically considered and excluded several potential confounding factors such as age, gender, resting motor threshold, EMG background activity and amplitude of the motor evoked potential elicited by the single-pulse test stimuli. Our results show that short-interval intracortical inhibition is decreased in Parkinson's disease compared to controls. This reduction of intracortical inhibition was obtained with relatively low-intensity conditioning stimuli (80% of the resting motor threshold) and was not associated with any significant increase in short-interval intracortical facilitation or intracortical facilitation with the same low-intensity conditioning stimuli, supporting the involvement of cortical inhibitory circuits. Short-interval intracortical inhibition was similarly reduced in levodopa-naïve, non-dyskinetic and dyskinetic patients. Importantly, intracortical inhibition was reduced compared to control subjects also on the less affected side (n = 145), even in de novo drug-naïve patients in whom the less affected side was minimally symptomatic (lateralized Unified Parkinson's Disease Rating Scale part III = 0 or 1, n = 23). These results suggest that cortical disinhibition is a very early, possibly prodromal feature of Parkinson's disease.

Transcranial Magnetic Resonance-Guided Focused Ultrasound Thalamotomy in Essential Tremor: A Comprehensive Lesion Characterization.

BACKGROUND: Transcranial magnetic resonance-guided focused ultrasound (tcMRgFUS) thalamotomy is a novel and effective treatment for controlling tremor in essential tremor patients. OBJECTIVE: To provide a comprehensive characterization of the radiological, topographical, and volumetric aspects of the tcMRgFUS thalamic lesion, and to quantify how they relate to the clinical outcomes. METHODS: In this study, clinical and radiological data from forty patients with medically-refractory essential tremor treated with unilateral tcMRgFUS thalamotomy were retrospectively analyzed. Treatment efficacy was assessed with Clinical Rating Scale for Tremor (CRST). Lesions were manually segmented on T1, T2, and susceptibility-weighted images, and 3-dimensional topographical analysis was then carried out. Statistical comparisons were performed using nonparametric statistics. RESULTS: The greatest clinical improvement was correlated with a more inferior and posterior lesion, a bigger lesion volume, and percentage of the ventral intermediate nucleus covered by the lesion; whereas, the largest lesions accounted for the occurrence of gait imbalance. Furthermore, the volume of the lesion was significantly predicted by the number of sonications surpassing 52°C. CONCLUSION: Here we provide a comprehensive characterization of the thalamic tcMRgFUS lesion including radiological and topographical analysis. Our results indicate that the location and volume of the lesion were significantly associated with the clinical outcome and that mid-temperatures may be responsible for the lesion size. This could serve ultimately to improve targeting and judgment and to optimize clinical outcome of tcMRgFUS thalamotomy.

Focused ultrasound thalamotomy for multiple sclerosis-associated tremor.

Multiple sclerosis (MS)-related tremor is frequent and can often be refractory to medical treatment, which makes it a potential source of major disability. Functional neurosurgery approaches such as thalamic deep brain stimulation (DBS) or radiofrequency thalamotomy are proven to be effective, but the application of invasive techniques in MS tremor has so far been limited. Magnetic resonance (MR)-guided focused ultrasound thalamotomy, which has already been approved for treating essential and parkinsonian tremor, provides a minimally invasive approach that could be useful in the management of MS tremor. We report for the first time a patient with medically refractory MS-associated tremor successfully treated by focused ultrasound thalamotomy.

Microstructural changes of the dentato-rubro-thalamic tract after transcranial MR guided focused ultrasound ablation of the posteroventral VIM in essential tremor.

Essential tremor is the most common movement disorder in adults. In patients who are not responsive to medical treatment, functional neurosurgery and, more recently, transcranial MR-guided focused ultrasound thalamotomy are considered effective therapeutic approaches. However, the structural brain changes following a thalamotomy that mediates the clinical improvement are still unclear. In here diffusion weighted images were acquired in a cohort of 24 essential tremor patients before and 3 months after unilateral transcranial MR-guided focused ultrasound thalamotomy targeting at the posteroventral part of the VIM. Microstructural changes along the DRTT were quantified by means of probabilistic tractography, and later related to the clinical improvement of the patients at 3-months and at 1-year after the intervention. In addition the changes along two neighboring tracts, that is, the corticospinal tract and the medial lemniscus, were assessed, as well as the relation between these changes and the presence of side effects. Thalamic lesions produced local and distant alterations along the trajectory of the DRTT, and each correlated with clinical improvement. Regarding side effects, gait imbalance after thalamotomy was associated with greater impact on the DRTT, whereas the presence of paresthesias was significantly related to a higher overlap between the lesion and the medial lemniscus. This work represents the largest series describing the microstructural changes following transcranial MR-guided focused ultrasound thalamotomy in essential tremor. These results suggest that clinical benefits are specific for the impact on the cerebello-thalamo-cortical pathway, thus reaffirming the potential of tractography to aid thalamotomy targeting.