Radiofrequency Ablation for Movement Disorders: Risk Factors for Intracerebral Hemorrhage, a Retrospective Analysis

Ultrasound Applications in the Treatment of Major Depressive Disorder (MDD): A Systematic Review of Techniques and Efficacy

Objective

Major depressive disorder (MDD) is a debilitating mental health condition characterized by persistent feelings of sadness, loss of interest, and impaired daily functioning. It affects approximately 8% of the U.S. population, posing a significant personal and economic burden. Around 30% of patients with MDD do not respond to conventional antidepressant and psychotherapeutic treatments. Current treatment options for refractory MDD include transcranial magnetic stimulation (TMS) and invasive surgical procedures such as surgical ablation, vagus nerve stimulation, and deep brain stimulation. TMS has modest efficacy, and surgical procedures are associated with surgical risk and low patient acceptance. With the unique advantage of combining non-invasiveness with selective targeting, therapeutic ultrasound emerges as a promising alternative for treating refractory MDD. Over the past 10 years, there has been a growth in focused ultrasound research, leading to an exponential increase in academic and public interest in the technology. To support the continued development of ultrasound for treating MDD, we conducted a systematic review following Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA) guidelines.

Methods

We included peer-reviewed prospective cohort studies, case-control studies, and randomized control trials that evaluate the efficacy of ultrasonic treatment for depression (PROSPERO registration number: CRD42024626093). We summarized ultrasonic techniques for treating depression and their efficacy. Furthermore, we identified key challenges and future directions for applying ultrasound in treating MDD.

Results

We identified 67 potentially relevant articles, of which 18 studies met all inclusion criteria. The techniques of applying ultrasound to treat depression include magnetic resonance-guided focused ultrasound (MRgFUS) for capsulotomy and low-intensity focused ultrasound (LIFUS) neuromodulation. In human trials, the response rate (⩾50% improvement from baseline on depression score) is 53.85% for MRgFUS and 80.49% for LIFUS neuromodulation. In all preclinical studies using rodent models (8 studies), LIFUS neuromodulation had a medium to large effect (|Cohen's d| > 0.6) on resolving depressive-like behavior in rodents without causing adverse effects such as tissue damage. MRgFUS faces inconsistent lesioning success and a limited response rate, while LIFUS neuromodulation lacks systematic exploration of parameter space and a clear understanding of its mechanistic effects. Future work should refine patient selection for MRgFUS and focus on individualized functional targeting.

Conclusion

LIFUS neuromodulation showed a medium to large effect in reducing depressive behaviors in both rodent models and human trials, representing a promising, noninvasive option for treating refractory MDD.

Radiofrequency thalamotomy for tremor produces focused and predictable lesions shown on magnetic resonance images

Radiofrequency thalamotomy is a neurosurgical management option for medically-refractory tremor. In this observational study, we evaluate the MRI features of the resultant lesion, their temporal dynamics, and how they vary depending on surgical factors. We report on lesion characteristics including size and location, as well as how these vary over time and across different MRI sequences. Data from 12 patients (2 essential tremor, 10 Parkinson's disease) who underwent unilateral radiofrequency thalamotomy for tremor were analysed. Lesion characteristics were compared across five structural sequences. Volumetric analysis of lesion features was performed at early (<5 weeks) and late (>5 months) timepoints by manual segmentation. Lesion location was determined after registration of lesions to standard space. All patients showed tremor improvement (clinical global impressions scale) postoperatively. Chronic side-effects included balance disturbances (n = 4) and worsening mobility due to parkinsonism progression (n = 1). Early lesion features including a necrotic core, cytotoxic oedema and perilesional oedema were best demarcated on T2-weighted sequences. Multiple lesions were associated with greater cytotoxic oedema compared with single lesions (T2-weighted mean volume: 537 ± 112 mm³ versus 302 ± 146 mm³, P = 0.028). Total lesion volume reduced on average by 90% between the early and late scans (T2-weighted mean volume: 918 ± 517 versus 75 ± 50 mm³, t = 3.592, P = 0.023, n = 5), with comparable volumes demonstrated at ∼6 months after surgery. Lesion volumes on susceptibility-weighted images were larger than those of T2-weighted images at later timepoints. Radiofrequency thalamotomy produces focused and predictable lesion imaging characteristics over time. T2-weighted scans distinguish between the early lesion core and oedema characteristics, while lesions may remain more visible on susceptibility-weighted images in the months following surgery. Scanning patients in the immediate postoperative period and then at 6 months is clinically meaningful for understanding the anatomical basis of the transient and permanent effects of thalamotomy.

Tremor in Parkinson's Disease: From Pathophysiology to Advanced Therapies

Background

Tremor is one of the most prevalent symptoms in Parkinson's Disease (PD). The progression and management of tremor in PD can be challenging, as response to dopaminergic agents might be relatively poor, particularly in patients with tremor-dominant PD compared to the akinetic/rigid subtype. In this review, we aim to highlight recent advances in the underlying pathogenesis and treatment modalities for tremor in PD.

Methods

A structured literature search through Embase was conducted using the terms "Parkinson's Disease" AND "tremor" OR "etiology" OR "management" OR "drug resistance" OR "therapy" OR "rehabilitation" OR "surgery." After initial screening, eligible articles were selected with a focus on published literature in the last 10 years.

Discussion

The underlying pathophysiology of tremor in PD remains complex and incompletely understood. Neurodegeneration of dopaminergic neurons in the retrorubral area, in addition to high-power neural oscillations in the cerebello-thalamo-cortical circuit and the basal ganglia, play a major role. Levodopa is the first-line therapeutic option for all motor symptoms, including tremor. The addition of dopamine agonists or anticholinergics can lead to further tremor reduction. Botulinum toxin injection is an effective alternative for patients with pharmacological-resistant tremor who are not seeking advanced therapies. Deep brain stimulation is the most well-established advanced therapy owing to its long-term efficacy, reversibility, and effectiveness in other motor symptoms and fluctuations. Magnetic resonance-guided focused ultrasound is a promising modality, which has the advantage of being incisionless. Cortical and peripheral electrical stimulation are non-invasive innovatory techniques that have demonstrated good efficacy in suppressing intractable tremor.