Radiofrequency thalamotomy for tremor outcomes correlate with dentorubrothalamic tract distance

Abstract

Background: Thalamotomy was the main surgical treatment for medically refractory tremor before deep brain stimulation (DBS). While DBS is now preferred, it has drawbacks such as hardware failure, infection risk, frequent battery replacements, and multiple programming adjustments. Radiofrequency (RF) thalamotomy avoids these issues, can be performed under local anaesthesia, and suits patients in poor health. This study examines long-term outcomes of RF thalamotomy.

Methods: We reviewed 14 consecutive RF thalamotomies performed in Oxford from 2016 to 2021. Three patients died from unrelated causes, leaving eight for long-term assessment. We recorded Bain and Findlay (BF) tremor scores, Clinical Global Impression of Severity (CGI-S), Clinical Global Impression of Change (CGI-C), Patient's Global Impression of Change (PGI-C), and Efficacy Index (EI). The median follow-up was 39 months (range 12-126). Post-operative tractography was correlated with clinical outcomes.

Results: Six patients had essential tremor and eight had Parkinson's disease. Reasons for choosing thalamotomy over DBS included medical comorbidities, patient preference, age, and previous DBS failure. Ten patients (71%) reported significant tremor improvement, with relapse in two after six months. The mean BF tremor score decreased from 16.1 preoperatively to 8.5 postoperatively (p = 0.0043). Adverse events occurred in seven patients (50%), resolving completely in three, partially in three, and persisting in one. Sustained outcomes correlated with a wider distance of residual dentrorubrothalamic tract (DRTT) fibres from the lesion.

Conclusions: RF thalamotomy is an effective long-term treatment for medication-refractory tremor and should be considered for select patients needing unilateral tremor control.

Keywords: DBS; Essesntial Tremors (ET); Magnetic Resonance Guided Focused Ultrasound (MRgFUS); Parkinson’s disease (PD); Radiofrequency (RF) Lesioning; Thalamotomy.