Essential tremor (ET) is the most prevalent movement disorder in adults, and can often be medically refractory, requiring surgical intervention. MRI-guided focused ultrasound (MRgFUS) is a less invasive procedure that uses ultrasonic waves to induce lesions in the ventralis intermedius nucleus (VIM) to treat refractory ET. As with all procedures for treating ET, optimal targeting during MRgFUS is essential for efficacy and durability. Various studies have reported cases of tremor recurrence following MRgFUS and long-term outcome data is limited to 3–4 years. We present a tractography-based investigation on a case of DBS rescue for medically refractory ET that was treated with MRgFUS that was interrupted due to the development of dysarthria during the procedure. After initial improvement, her hand tremor started to recur within 6 months after treatment, and bilateral DBS was performed targeting the VIM 24 months after MRgFUS. DBS induced long-term tremor control with monopolar stimulation. Diffusion MRI tractography was used to reconstruct the dentatorubrothalamic (DRTT) and corticothalmic (CTT) tracts being modulated by the procedures to understand the variability in efficacy between MRgFUS and DBS in treating ET in our patient. By comparing the MRgFUS lesion and DBS volume of activated tissue (VAT), we found that the MRgFUS lesion was located ventromedially to the VAT, and was less than 10% of the size of the VAT. While the lesion encompassed the same proportion of DRTT streamlines, it encompassed fewer CTT streamlines than the VAT. Our findings indicate the need for further investigation of targeting the CTT when using neuromodulatory procedures to treat refractory ET for more permanent tremor relief.

中文翻译：

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特发性震颤的次优 MR 引导聚焦超声丘脑切开术后深部脑刺激拯救的病例报告：基于牵引成像的调查

特发性震颤 (ET) 是成人中最普遍的运动障碍，通常在医学上是难治的，需要手术干预。MRI 引导的聚焦超声 (MRgFUS) 是一种侵入性较小的手术，它使用超声波诱导腹中间核 (VIM) 中的病变来治疗难治性 ET。与治疗 ET 的所有程序一样，MRgFUS 期间的最佳靶向对于疗效和持久性至关重要。各种研究报告了 MRgFUS 后震颤复发的病例，长期结果数据仅限于 3-4 年。我们对一例 DBS 抢救医学难治性 ET 的病例进行了基于牵引成像的调查，该病例接受 MRgFUS 治疗，该病例因手术过程中出现构音障碍而中断。经过初步改进，她的手震颤在治疗后 6 个月内开始复发，并在 MRgFUS 后 24 个月进行了针对 VIM 的双侧 DBS。DBS 通过单极刺激诱导长期震颤控制。扩散 MRI 束成像用于重建由程序调节的齿突丘脑 (DRTT) 和皮质丘脑 (CTT) 束，以了解 MRgFUS 和 DBS 在治疗我们患者的 ET 中的疗效差异。通过比较MRgFUS病变和DBS体积的活化组织（VAT），我们发现MRgFUS病变位于VAT腹内侧，小于VAT大小的10%。虽然病变包含相同比例的 DRTT 流线，但它包含的 CTT 流线少于增值税。