Comprehensive Evaluation of Factors Affecting Tremor Relapse after MRgFUS Thalamotomy: A Case-Control Study

Abstract

Objective: To identify possible relevant factors contributing to tremor relapse after MRgFUS thalamotomy in patients with essential tremor (ET) and Parkinson’s disease (PD). Methods: We identified patients with tremor relapse from a series of 79 treatments in a single institution. The demographic and clinical characteristics of the study group patients were compared to those of patients who did not relapse in the same follow-up period. Imaging and procedural factors were compared using a control group matched for clinical and demographic characteristics. Results: Concerning clinical and demographic characteristics, we did not find statistically significant differences in gender and age. Seventy-three percent of patients with tremor relapse were Parkinson’s disease patients. Using MRI, we found larger thalamotomy lesions at the 1-year follow-up in the control group with stable outcomes, compared to patients with tremor relapse. In the tractography evaluation, we found a more frequent eccentric position of the DRTt in patients with tremor relapse. Conclusions: The most relevant determining factors for tremor relapse after MRgFUS thalamotomy appear to be tremor from Parkinson’s disease and inaccurate thalamic targeting. Size of the thalamotomy lesion can also influence the outcome of treatment.

Evaluation of Cerebral Volume Changes in Patients with Tremor Treated by MRgFUS Thalamotomy

“…From a clinical point of view, Parkinsonian tremor is known to relapse more frequently than essential tremor, while gender, age or disease duration are not significant factors. Among the imaging findings, some studies suggest that the size of the thalamotomy lesion may be instrumental in determining the stability of treatment effects [ 11 , 12 ].…”

“…Numerous studies have used imaging techniques to demonstrate the presence of structural and functional brain alterations in patients with TE and PD [ 8 , 9 , 10 ]. Some previous reports in the literature also explored the possible prognostic value of imaging finding, using standard and advanced imaging techniques, in patients submitted to pharmacological, surgical, and less invasive treatments for tremor [ 11 , 12 , 13 , 14 , 15 ].…”

Focused ultrasound and other lesioning in the treatment of tremor

“…Many U.S. centers screen out candidates for MRgFUS with a skull density ratio (SDR) <0. 40 based on screening head CT. Low SDR is associated with increased difficulty focusing the ultrasound beams and achieving therapeutic temperatures at the target. During MRgFUS thalamotomy, the patient's head is shaved and fixed in a stereotactic frame under local anesthesia.…”

“…In addition to VIM thalamotomy for ET, others have ablated the dentatorubrothalamic (DRT) tract with MRgFUS with results comparable to VIM thalamotomy [30][31][32]. Incorporation of diffusion tensor imaging (DTI) tractography has been demonstrated in multiple studies to potentially improve targeting and safety of VIM thalamotomy [33][34][35][36][37][38][39][40].…”

Neurotrophins as Therapeutic Agents for Parkinson’s Disease; New Chances From Focused Ultrasound?

“…As several other teams worldwide, they are acquiring experience around potential limitations (i.e., skull density ratio and skull volume in the treatment area, which limit the energy transfer throughout the skull and influence the temperature increase in the lesioning area; the number and maximal average temperature-Tmax-Avg-of sonication during treatment; and the accuracy of targeting, the optimal lesion volume), rare adverse events, and the degree of tremor re-occurrence during follow-up (Bruno et al, 2020b(Bruno et al, , 2021bTommasino et al, 2021; Figure 2).…”