To evaluate the safety and efficacy of a modern linear accelerator with non-invasive thermoplastic mask-based immobilization as an alternative treatment for medically refractory tremor.

Essential and Parkinsonian tremors are prevalent movement disorders impacting millions globally. Although Gamma Knife radiosurgery remains a conventional treatment for these tremors, it demands invasive frame immobilization, long-treatment time, & periodic Co-60 source replacements.

From 2017 to 2022, we treated 40 patients with medically refractory essential or Parkinsonian tremor using a linear accelerator approach at the University of Alabama at Birmingham. All patients could not or did not wish to undergo deep brain stimulation (DBS). We assessed tremor severity with the Fahn-Tolosa-Marin (FTM) scale and considered secondary outcomes such as quality of life & patient satisfaction.

With minimum one year follow-up, a significant 84.6% of patients exhibited a marked reduction in tremor severity, averaging a 56.0% decrease on the FTM scale. We observed a notable improvement in midline tremor scores over time. Our method demonstrated efficacy and side effect profiles comparable to the Gamma Knife but with enhanced patient comfort and speed. Four patients faced clinically significant neurological side effects, necessitating extended steroid or bevacizumab treatment. Limitations of our study include lack of blinding in tremor evaluation and some loss to follow-up, partly influenced by the COVID pandemic.

While MRgFUS is gaining traction for thalamotomies, our technique remains a strong contender, especially for those where MRgFUS might not be suitable due to skull density or patient disinterest in head shaving and frame fixation requirement. 

Frameless radiosurgical thalamotomy, utilizing a contemporary linear accelerator, is a safe and potent treatment for medically refractory tremor. This study reinforces its benefits and highlights its convenience & attractiveness for treating medically refractory tremor. Future study will examine the role of modern tractography in improving targeting beyond the traditional VIM.