Tremor relief after gamma knife thalamotomy for Parkinson's disease

Parkinsonian tremor can remain disabling despite optimized medical therapy, impairing writing, drinking, feeding, and other activities of daily living. Gamma Knife radiosurgical (GKRS) thalamotomy is an incisionless surgical option for tremor patients who require chronic anticoagulation or have other major comorbidities for more invasive alternatives. We retrospectively evaluated the outcomes of 42 Gamma Knife thalamotomy procedures performed for medically refractory Parkinsonian tremor during the 1996 - 2020 interval. Outcomes parameters included clinical benefit, initial tremor relief, recurrence, motor functional improvement, and complications. Functional outcomes were assessed using Fahn-Tolosa-Marín (FTM) subscore composed of tremor, writing, drawing, and drinking domains. The median age at treatment was 76.5 years (IQR, 72.0-81.8), and median final follow-up was 14.0 months (IQR, 8.0-28.2). Clinical benefit occurred in 37 of 42 patients (88.1%), with a median time to onset of benefit of 4.0 months (IQR, 3.0-6.0). Tremor arrest occurred in 14 of 40 evaluable patients (35.0%), and complete arrest occurred in 10 of 40 (25.0%). The median total tremor-related FTM subscore improved from 12 before treatment to 4 after treatment, corresponding to a median relative improvement of 54.2% (p < 0.001). Temporary adverse effects occurred in 5 patients (11.9%). No definite tremor recurrence was documented. GKRS thalamotomy provides meaningful clinical benefit and significant tremor-related functional improvement with a low complication rate in selected patients with medically refractory Parkinsonian tremor. It remains a valuable incisionless surgical option for tremor-dominant Parkinson's disease when medical or more invasive therapies are unsuitable.