Gamma Knife radiosurgery in patients with indwelling deep brain stimulator systems

INTRODUCTION: Deep brain stimulation (DBS) is an established therapy for medically intractable movement disorders but poor response or habituation may prompt noninvasive salvage strategies. Stereotactic radiosurgery (SRS) offers targeted lesioning with a favourable risk profile, yet feasibility in patients with indwelling DBS systems remains underreported. We describe two patients with implanted DBS hardware who underwent Gamma Knife SRS (GKSRS) for intracranial pathologies. CASE PRESENTATIONS: Case 1: a 33-year-old female with right thalamic/midbrain arteriovenous malformation (AVM), developed Holmes rubral tremor after hemorrhage, requiring left thalamic DBS in 2018. After further AVM hemorrhage in 2022, a third GKSRS treatment was performed in 2025, (0.321 cc, 15 Gy prescription dose to 52% isodose line), with radiofrequency exposure limited to ≤2.0 μT to protect DBS components. Case 2: a 44-year-old female with multiple sclerosis and left-sided trigeminal neuralgia underwent Gamma Knife radiosurgery for facial pain in 2017 (40 Gy to 50% isodose line) and bilateral thalamic DBS implantation for tremor within the same year. Following pain recurrence despite maximum medical therapy, a second GKSRS was performed in 2019 using identical treatment parameters with bilateral DBS in place. Cone-beam computed tomography (CBCT) verification in Case 1 demonstrated <0.5mm maximal translational or rotational discrepancies, confirming acceptable registration accuracy despite metallic artifacts from DBS hardware. Ongoing follow up has not identified any stimulation-related adverse effects. CONCLUSION: This series demonstrates the safety and technical feasibility of GKSRS in patients with indwelling DBS, with CBCT confirming adequate precision despite metallic implants. GKSRS may be a viable salvage option for suboptimal DBS outcomes, avoiding surgical device removal risks. Larger cohorts are warranted to establish consensus guidelines for target planning and device management in neural implant patients undergoing radiation therapy.