Is staged bilateral thalamic radiosurgery an option for otherwise surgically ineligible patients with medically refractory bilateral tremor?

Abstract

OBJECTIVE Unilateral Gamma Knife thalamotomy (GKT) is a well-established treatment for patients with medically refractory tremor who are not eligible for invasive procedures due to increased risk of compications. The purpose of this study was to evaluate whether staged bilateral GKT provides benefit with acceptable risk to patients suffering from disabling medically refractory bilateral tremor. METHODS Eleven patients underwent staged bilateral GKT during a 17-year period (1999-2016). Eight patients had essential tremor (ET), 2 had Parkinson's disease (PD)-related tremor, and 1 had multiple-sclerosis (MS)-related tremor. For the first GKT, a median maximum dose of 140 Gy was delivered to the posterior-inferior region of the nucleus ventralis intermedius (VIM) through a single isocenter with 4-mm collimators. Patients who benefitted from unilateral GKT were eligible for a contralateral GKT 1-2 years later (median 22 months). For the second GKT, a median maximum dose of 130 Gy was delivered to the opposite VIM nucleus to a single 4-mm isocenter. The Fahn-Tolosa-Marin (FTM) clinical tremor rating scale was used to score tremor, drawing, and drinking before and after each GKT. The FTM writing score was assessed only for the dominant hand before and after the first GKT. The Karnofsky Performance Status (KPS) was used to assess quality of life and activities of daily living before and after the first and second GKT. RESULTS The median time to last follow-up after the first GKT was 35 months (range 11-70 months). All patients had improvement in at least 1 FTM score after the first GKT. Three patients (27.3%) had tremor arrest and complete restoration of function (noted via FTM tremor, writing, drawing, and drinking scores equaling zero). No patient had tremor recurrence or diminished tremor relief after the first GKT. One patient experienced new temporary neurological deficit (contralateral lower-extremity hemiparesis) from the first GKT. The median time to last follow-up after the second GKT was 12 months (range 2-70 months). Nine patients had improvement in at least 1 FTM score after the second GKT. Two patients had tremor arrest and complete restoration of function. No patient experienced tremor recurrence or diminished tremor relief after the second GKT. No patient experienced new neurological or radiological adverse effect from the second GKT. Statistically significant improvements were noted in the KPS score following the first and second GKT. CONCLUSIONS Staged bilateral GKT provided effective relief for medically refractory, disabling, bilateral tremor without increased risk of neurological complications. It is an appropriate strategy for carefully selected patients with medically refractory bilateral tremor who are not eligible for deep brain stimulation.

Neurological adverse event profile of magnetic resonance imaging–guided focused ultrasound thalamotomy for essential tremor

“…Unlike earlier studies of radiofrequency thalamotomy, this AE was usually not severe, considered mild in 90% of affected patients . These results are similar to those reported with radiosurgery, another incisionless procedure applied not only to unilateral, but also bilateral treatment of ET . The safety profile of MRgFUS suggests that bilateral MRgFUS thalamotomy could be safely performed on selected patients.…”

Adoption of focused ultrasound thalamotomy for essential tremor: why so much fuss about FUS?

“…This is occurring despite unclear reimbursement policies in many countries 15 and a lack of acceptance of bilateral treatments, (as opposed to GK where there are precedents for bilateral interventions. [16][17][18] The increased adoption is associated with a higher number of publications (figure 2) as well as higher-quality evidence for FUS treatments (table 1). Despite the fact that SRS has been available longer than DBS and arguably provides non-invasive lesion generation capabilities similar to FUS, the enthusiasm for GK has remained fairly moderate.…”

Radiotherapy of non-tumoral refractory neurological pathologies

“…Two prospective series highlighted a clinical improvement in the activities of daily living [99,100]. In selected patients, staged bilateral SRS thalamotomy can be proposed with a satisfactory benefit/risk ratio [101].…”