Six-Year Single Centre Experience with Frameless, Fiducial-Less Deep Brain Stimulation in Parkinsons Disease: Accuracy, Outcomes, and Clinical Feasibility

Background: Frameless and fiducial-less deep brain stimulation (DBS) guided by intraoperative cone-beam CT has emerged as a less invasive alternative to frame-based stereotaxy, yet comprehensive long-term data remain limited. This study summarizes six years of institutional experience with O-arm–navigated, frameless, fiducial-less subthalamic nucleus (STN) DBS for Parkinson’s disease. Methods: Forty-two consecutive patients with idiopathic Parkinson’s disease underwent bilateral STN-DBS using O-arm–based registration and NexFrame targeting between 2018 and 2024. Preoperative planning incorporated structural MRI and diffusion tractography–derived connectivity-based STN parcellation. Accuracy was assessed by postoperative CT–MRI fusion, and clinical outcomes were evaluated at 12 months using UPDRS III and levodopa equivalent daily dose (LEDD). Postoperative lead reconstruction and volume-of-tissue-activation modelling were performed in SureTune 3. Results: All 84 electrodes were successfully implanted with a mean target registration error of 0.47 ± 0.09 mm and a mean vector error of 1.19 ± 0.48 mm. No lead revisions were required. At 12 months, UPDRS III improved from 33.4 ± 7.2 to 14.6 ± 4.9 (−56.3%; p < 0.001), and LEDD decreased by 49.9% (p < 0.001). Complications were minor and included one transient peri-lead edema and one connector-related issue. In most patients, active contacts were located within the dorsolateral (motor) STN, consistent with robust clinical benefit. Conclusions: In this single-centre retrospective series, O-arm–navigated frameless and fiducial-less STN-DBS was associated with favourable implantation accuracy, good motor outcomes, and a low complication rate. In the absence of a contemporaneous control cohort, these findings should be interpreted as supporting the technical feasibility and clinical utility of this workflow rather than demonstrating superiority or non-inferiority versus frame-based DBS.