Frailty and Outcomes after Unilateral MRgFUS Thalamotomy for Tremor

Introduction: Frailty is recognized as an important predictor of neurointerventional outcomes. MRI-guided focused ultrasound (MRgFUS) thalamotomy is a recognized treatment option for patients with refractory ET and TdPD. We aimed to evaluate whether frailer MRgFUS thalamotomy patients had worse tremor outcomes or more complications.

Methods: We performed a cohort analysis using MRgFUS data collected from 2020 to 2023. Inclusion criteria were unilateral MRgFUS thalamotomy for ET or TdPD with available follow up data (minimum of three-month follow up). Frailty was assessed using the modified Frailty Score 11 (mFI-11), which includes 11 medical comorbidities. Tremor outcomes were assessed using the Clinical Rating Scale for Tremor Part B (CRST-B). Complications assessed included disturbances of sensation, speech and swallowing, balance and gait, and strength.

Results: We identified 169 eligible patients, including 135 (79.9%) ET and 34 (20.1%) TdPD patients. Combined average follow-up was 10.3±5.8 months (range 3-24 months), with cohort specific follow up of ET=10.8±6.0 months and TdPD=8.6±4.6 months. Between the ET and TdPD cohorts, no significant differences existed in age, sex, handedness, side treated, skull density ratio, number of sonications, peak/average temperatures, energy delivered, BMI, or ASA Classification. For medical comorbidities, only hypertension was significantly different (ET=65.9%, TdPD=47.1%, p=0.043). The ET patients were significantly frailer overall, with 20.7% ET and 35.3% TdPD patients robust (mFI-11=0), 14.8% ET and 32.4% TdPD patients pre-frail (mFI-11=1), 25.9% ET and 8.8% TdPD patients frail (mFI-11=2), and 38.5% ET and 23.5% TdPD patients severely frail (mFI-11=3+) (p=0.007). There were no significant differences in tremor outcomes in the combined (p=0.833), ET (p=0.902), or TdPD cohorts (p=0.501), or in any symptoms at last follow up (all p>0.05).

Conclusion : ET patients are frailer than TdPD patients selected for MRgFUS. Increasing frailty is not associated with worse outcomes, suggesting MRgFUS may be appropriate even for frailer patients.