Frameless, Virtual Cone Linac-based Stereotactic Radiosurgery for Essential & Parkinsonian Tremor: A Phase I/II Prospective Clinical Trial (S35.001).

Objective: 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.

Background: 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.

Design/methods: 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.

Results: 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.

Conclusions: 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. Dr. Thomas has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Varian Medical Systems. The institution of Dr. Thomas has received research support from Varian Medical Systems. Dr. Walker has nothing to disclose. Erik Middlebrooks has received personal compensation in the range of $10,000-$49,999 for serving as a Consultant for Varian Medical Systems Inc. Erik Middlebrooks has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Boston Scientific Corp. The institution of Erik Middlebrooks has received research support from Varian Medical Systems Inc. Dr. Stover has nothing to disclose. Dr. Sung has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Teva Neuroscience. Dr. Sung has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Genentech. Dr. Sung has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Neurocrine. Dr. Sung has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for UniQure. Dr. Standaert has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Abbvie, Inc. Dr. Standaert has received personal compensation in the range of $500-$4,999 for serving as a Consultant for Curium Pharma. Dr. Standaert has received personal compensation in the range of $5,000-$9,999 for serving as a Consultant for Gray Matter Technologies. Dr. Standaert has received personal compensation in the range of $5,000-$9,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Sanofi-Aventis. Dr. Standaert has received personal compensation in the range of $500-$4,999 for serving on a Scientific Advisory or Data Safety Monitoring board for Theravance, Inc. Dr. Standaert has received personal compensation in the range of $10,000-$49,999 for serving as an Editor, Associate Editor, or Editorial Advisory Board Member for International Parkinson and Movement Disorder Society. The institution of Dr. Standaert has received research support from Abbvie, Inc. The institution of Dr. Standaert has received research support from American Parkinson Disease Association. The institution of Dr. Standaert has received research support from Department of Defense. The institution of Dr. Standaert has received research support from National Institutes of Health. Dr. Standaert has received publishing royalties from a publication relating to health care. Dr. Standaert has received personal compensation in the range of $500-$4,999 for serving as a Speaker with Case Western Reserve. Dr. Standaert has received personal compensation in the range of $500-$4,999 for serving as a Consultant with California Pacific Medical Center. Dr. Standaert has received personal compensation in the range of $500-$4,999 for serving as a Course Instructor with International Parkinson Disease and Movement Disorders Society. Dr. Standaert has received personal compensation in the range of $500-$4,999 for serving as a Reviewer with National Institutes of Health. Dr. Standaert has received personal compensation in the range of $500-$4,999 for serving as a Consultant with Parkinson Study Group. Dr. Standaert has received personal compensation in the range of $500-$4,999 for serving as a Speaker with UCSD. Dr. Standaert has received personal compensation in the range of $500-$4,999 for serving as a Reviewer with Warren Alpert Foundation. Dr. Standaert has a non-compensated relationship as a Chair, Scientific Advisory Board with American Parkinson Disease Association that is relevant to AAN interests or activities. Dr. Bentley has nothing to disclose. Dr. Popple has received personal compensation in the range of $500-$4,999 for serving on a Speakers Bureau for Varian Medical Systems. The institution of Dr. Popple has received research support from Varian Medical Systems. Dr. Popple has received intellectual property interests from a discovery or technology relating to health care.