Double lesion MRgFUS treatment of essential tremor targeting the thalamus and posterior sub-thalamic area: preliminary study with two year follow-up

Abstract

Background: MR-guided focused ultrasound (MRgFUS) is an effective treatment for essential tremor (ET). However, the optimal intracranial target sites remain to be determined. Objective: To assess MRgFUS induced sequential lesions in (anterior-VIM/VOP nuclei) the thalamus and then posterior subthalamic area (PSA) performed during the same procedure for alleviating ET. Methods: 14 patients had unilateral MRgFUS lesions placed in anterior-VIM/VOP then PSA. Bain-Findley Spirals were collected during MRgFUS from the treated arm (BFS-TA) and throughout the study from the treated (BFS-TA) and non-treated (BFS-NTA) arms and scored by blinded assessors. Although, the primary outcome was change in the BFS-TA from baseline to 12 months we have highlighted the 24-month data. Secondary outcomes included the Clinical Rating Scale for Tremor (CRST), Quality of Life for ET (QUEST) and PHQ-9 depression scores. Results: The mean improvement in the BFS-TA from baseline to 24 months was 41.1% (p < 0.001) whilst BFS-NTA worsened by 8.8% (p < 0.001). Intra-operative BFS scores from the targeted arm showed a mean 27.9% (p < 0.001) decrease after anterior-VIM/VOP ablation and an additional 30.1% (p < 0.001) reduction from post anterior-VIM/VOP to post-PSA ablation. Mean improvements at 24 month follow-up in the CRST-parts A, B and C were 60.7%, 30.4% and 65.6% respectively and 37.8% in QUEST-tremor score (all p < 0.05). Unilateral tremor severity scores decreased in the treated arm (UETTS-TA) 72.9% (p ¼ 0.001) and non-treated arm (UETTS-NTA) 30.5% (p ¼ 0.003). At 24 months residual adverse effects were slight unsteadiness (n ¼ 1) and mild hemi-chorea (n ¼ 1). Conclusion: Unilateral anterior-VIM/VOP and PSA MRgFUS significantly diminished contralateral arm tremor with improvements in arm function, tremor related disability and quality of life, with an acceptable adverse event profile.

The cost-effectiveness of unilateral magnetic resonance-guided focused ultrasound in comparison with unilateral deep brain stimulation for the treatment of medically refractory essential tremor in England

“…The proportion of the mrET population moving to each health state at each cycle was based on predicted population behaviour and response to treatment from the English Clinical Trial data 42 ( Table 1 ).…”

Target Selection for Magnetic Resonance‐Guided Focused Ultrasound in the Treatment of Parkinson's Disease

“…43 Research shows that ablation of Vim/Vop can mainly alleviate tremor while also alleviating rigidity and bradykinesia. 18,44,45 The first clinical experience regarding the use of MRgFUS for symptomatic treatment of PD was reported by Schlesinger and colleagues. 18 Seven PD patients underwent unilateral Vim-MRgFUS to improve severe refractory tremor.…”

“…There is also a small nuclei called the ventralis oralis posterior (Vop) that is closely related to Vim, which makes it difficult to clearly distinguish between the two 43 . Research shows that ablation of Vim/Vop can mainly alleviate tremor while also alleviating rigidity and bradykinesia 18,44,45 . Figure 4 is the post‐treatment image showing successful targeting Vim in a PD patient with four times follow‐up.…”

Update in the clinical application of focused ultrasound

“…Otherwise, thalamic DBS rescue can also be contemplated in case of ultrasound thalamotomy failure [38,39]. Finally, alternative approaches, such as cerebellothalamic tractotomy [40] or a combined Vim and posterior subthalamic area double lesion approach [41] have been successfully tested.…”