Speech Changes After Second-Side Magnetic Resonance-Guided Focused Ultrasound (MRgFUS) Thalamotomy: Is Intraoperative Speech Evaluation Associated With Speech Outcomes?

Introduction Staged bilateral magnetic resonance-guided focused ultrasound (MRgFUS) thalamotomy is an emerging option for the treatment of bilateral essential tremor (ET). However, there is historical concern that permanent bilateral thalamic lesioning leads to high rates of speech complications. This study evaluates bilateral MRgFUS thalamotomy of the ventral intermediate nucleus (VIM) for essential hand tremor, focusing on the impact of intraoperative speech monitoring during second-side procedures and its association with speech-related adverse effects (AEs). Methods A retrospective review was conducted, including 13 patients who underwent staged bilateral MRgFUS thalamotomy for medication-refractory hand tremor at Miami Valley Hospital between April 2020 and March 2023. Data collected included demographics, operative parameters, and AEs. Tremor outcomes and complications were assessed immediately following each procedure and at scheduled follow-up visits two weeks postoperatively. During the second-side procedure, a speech therapist conducted formal perioperative and intraoperative speech evaluations to identify deviations from baseline. Patients who reported speech changes at the two-week follow-up after the second-side procedure were contacted two years postoperatively for further assessment. Only descriptive statistics were utilized because of the small sample size. Results All 13 patients achieved near-complete bilateral tremor resolution. Following the first-side procedure, 23.1% of patients reported changes in speech. Additional AEs following the first-side procedure included lip numbness (30.8%), finger numbness (8.0%), and unsteady gait (8.0%). Nearly all resolved within two weeks. Following second-side treatment, immediate AEs included lip/tongue numbness (53.8%) and gait imbalance (8.0%). Only one patient (8.0%) reported an intraoperative speech change, and no patients deviated from baseline according to the formal intraoperative speech assessment. At the two-week follow-up, four patients (30.8%) reported taste disturbance, four (30.8%) reported lip/tongue numbness, three (23.1%) reported persistent subjective speech changes, one (8.0%) reported imbalance, and one (8.0%) reported bilateral leg weakness. Among the three patients reporting speech disturbance at the two-week follow-up, two reported complete resolution at the two-year follow-up, whereas one patient reported persistent mild slurring. Conclusions Staged bilateral MRgFUS VIM thalamotomy provided near-complete tremor control in all patients, with most AEs being transient or improving by short-term follow-up. Importantly, speech complications following the second-side procedure were lower than those historically reported with bilateral lesioning. Intraoperative deficits following second-side thalamotomy with intraoperative speech evaluation were limited and included only one long-term persistent case. This patient with persistent deficits was also the only patient to experience a transient speech change during the initial procedure. Incorporating intraoperative speech evaluation during second-side treatment may aid in minimizing language difficulties without compromising optimal targeting for maximal tremor control.