Changes in the Cerebello-Thalamo-Cortical Network After Magnetic Resonance-Guided Focused Ultrasound Thalamotomy

Magnetic Resonance-Guided Focused Ultrasound for Treatment of Essential Tremor: Ventral Intermediate Nucleus Ablation Alone or Additional Posterior Subthalamic Area Lesioning?

BACKGROUND

Magnetic resonance-guided focused ultrasound (MRgFUS) for treatment of essential tremor (ET) traditionally targets the ventral intermediate (Vim) nucleus. Recent strategies include a secondary lesion to the posterior subthalamic area (PSA).

OBJECTIVE

The aim was to compare lesion characteristics, tremor improvement, and adverse events (AE) between patients in whom satisfactory tremor suppression was achieved with lesioning of the Vim alone and patients who required additional lesioning of the PSA.

METHODS

Retrospective analysis of data collected from ET patients treated with MRgFUS at St Vincent's Hospital Sydney was performed. Clinical Rating Scale for Tremor (CRST), hand tremor score (HTS), and Quality of Life in Essential Tremor Questionnaire (QUEST) were collected pre- and posttreatment in addition to the prevalence of AEs. The lesion coordinates and overlap with the dentatorubrothalamic tract (DRTT) were evaluated using magnetic resonance imaging.

RESULTS

Twenty-one patients were treated in Vim only, and 14 were treated with dual Vim-PSA lesions. Clinical data were available for 29 of the 35 patients (19 single target and 10 dual target). At follow-up (mean: 18.80 months) HTS, CRST, and QUEST in single-target patients improved by 57.97% (P < 0.001), 36.71% (P < 0.001), and 58.26% (P < 0.001), whereas dual-target patients improved by 68.34% (P < 0.001), 35.37% (P < 0.003), and 46.97% (P < 0.005), respectively. The Vim lesion of dual-target patients was further anterior relative to the posterior commissure (PC) (7.84 mm), compared with single-target patients (6.92 mm), with less DRTT involvement (14.85% vs. 23.21%). Dual-target patients exhibited a greater proportion of patients with acute motor AEs (100% vs. 58%); however, motor AE prevalence was similar in both groups at long-term follow-up (33% vs. 38%).

CONCLUSION

Posterior placement of lesions targeting the Vim may confer greater tremor suppression. The addition of a PSA lesion, in patients with inadequate tremor control despite Vim lesioning, had a trend toward better long-term tremor suppression; however, this approach was associated with greater prevalence of gait disturbance in the short term.

Brain imaging studies of emotional well-being: a scoping review

This scoping review provides an overview of previous empirical studies that used brain imaging techniques to investigate the neural correlates of emotional well-being (EWB). We compiled evidence on this topic into one accessible and usable document as a foundation for future research into the relationship between EWB and the brain. PRISMA 2020 guidelines were followed. We located relevant articles by searching five electronic databases with 95 studies meeting our inclusion criteria. We explored EWB measures, brain imaging modalities, research designs, populations studied, and approaches that are currently in use to characterize and understand EWB across the literature. Of the key concepts related to EWB, the vast majority of studies investigated positive affect and life satisfaction, followed by sense of meaning, goal pursuit, and quality of life. The majority of studies used functional MRI, followed by EEG and event-related potential-based EEG to study the neural basis of EWB (predominantly experienced affect, affective perception, reward, and emotion regulation). It is notable that positive affect and life satisfaction have been studied significantly more often than the other three aspects of EWB (i.e., sense of meaning, goal pursuit, and quality of life). Our findings suggest that future studies should investigate EWB in more diverse samples, especially in children, individuals with clinical disorders, and individuals from various geographic locations. Future directions and theoretical implications are discussed, including the need for more longitudinal studies with ecologically valid measures that incorporate multi-level approaches allowing researchers to better investigate and evaluate the relationships among behavioral, environmental, and neural factors.

Systematic review registration

https://osf.io/t9cf6/.

Longitudinal MR imaging after unilateral MR-guided focused ultrasound thalamotomy: clinical and radiological correlation

Introduction

Magnetic-resonance-guided focused ultrasound (MRgFUS) thalamotomy uses multiple converging high-energy ultrasonic beams to produce thermal lesions in the thalamus. Early postoperative MR imaging demonstrates the location and extent of the lesion, but there is no consensus on the utility or frequency of postoperative imaging. We aimed to evaluate the evolution of MRgFUS lesions and describe the incidence, predictors, and clinical effects of lesion persistence in a large patient cohort.

Methods

A total of 215 unilateral MRgFUS thalamotomy procedures for essential tremor (ET) by a single surgeon were retrospectively analyzed. All patients had MR imaging 1 day postoperatively; 106 had imaging at 3 months and 32 had imaging at 1 year. Thin cut (2 mm) axial and coronal T2-weighted MRIs at these timepoints were analyzed visually on a binary scale for lesion presence and when visible, lesion volumes were measured. SWI and DWI sequences were also analyzed when available. Clinical outcomes including tremor scores and side effects were recorded at these same time points. We analyzed if patient characteristics (age, skull density ratio), preoperative tremor score, and sonication parameters influenced lesion evolution and if imaging characteristics correlated with clinical outcomes.

Results

Visible lesions were present in all patients 1 day post- MRgFUS and measured 307.4 ± 128.7 mm3. At 3 months, residual lesions (excluding patients where lesions were not visible) were 83.6% smaller and detectable in only 54.7% of patients (n = 58). At 1 year, residual lesions were detected in 50.0% of patients (n = 16) and were 90.7% smaller than 24 h and 46.5% smaller than 3 months. Lesions were more frequently visible on SWI (100%, n = 17), DWI (n = 38, 97.4%) and ADC (n = 36, 92.3%). At 3 months, fewer treatment sonications, higher maximum power, and greater distance between individual sonications led to larger lesion volumes. Volume at 24 h did not predict if a lesion was visible later. Lesion visibility at 3 months predicted sensory side effects but was not correlated with tremor outcomes.

Discussion

Overall, lesions are visible on T2-weighted MRI in about half of patients at both 3 months and 1 year post-MRgFUS thalamotomy. Certain sonication parameters significantly predicted persistent volume, but residual lesions did not correlate with tremor outcomes.

Tremor suppression following treatment with MRgFUS: skull density ratio consistency and degree of posterior dentatorubrothalamic tract lesioning predicts long-term clinical outcomes in essential tremor

Objectives

Magnetic resonance-guided focussed ultrasound (MRgFUS) is an incisionless ablative procedure, widely used for treatment of Parkinsonian and Essential Tremor (ET). Enhanced understanding of the patient- and treatment-specific factors that influence sustained long-term tremor suppression could help clinicians achieve superior outcomes via improved patient screening and treatment strategy.

Methods

We retrospectively analysed data from 31 subjects with ET, treated with MRgFUS at a single centre. Tremor severity was assessed with parts A, B and C of the Clinical Rating Scale for Tremor (CRST) as well as the combined CRST. Tremor in the dominant and non-dominant hand was assessed with Hand Tremor Scores (HTS), derived from the CRST. Pre- and post-treatment imaging data were analysed to determine ablation volume overlap with automated thalamic segmentations, and the dentatorubrothalamic tract (DRTT) and compared with percentage change in CRST and HTS following treatment.

Results

Tremor symptoms were significantly reduced following treatment. Combined pre-treatment CRST (mean: 60.7 ± 17.3) and HTS (mean: 19.2 ± 5.7) improved by an average of 45.5 and 62.6%, respectively. Percentage change in CRST was found to be significantly negatively associated with age (β = -0.375, p = 0.015), and SDR standard deviation (SDRSD; β = -0.324, p = 0.006), and positively associated with ablation overlap with the posterior DRTT (β = 0.535, p < 0.001). Percentage HTS improvement in the dominant hand decreased significantly with older age (β = -0.576, p < 0.01).

Conclusion

Our results suggest that increased lesioning of the posterior region of the DRTT could result in greater improvements in combined CRST and non-dominant hand HTS, and that subjects with lower SDR standard deviation tended to experience greater improvement in combined CRST.