Abstract
INTRODUCTION: Chronic subdural hematoma (cSDH) is a common condition in older adults that often requires neurosurgical evacuation. Postoperative delirium is a frequent and clinically relevant postoperative complication in this population. This study investigated whether burr hole craniotomy for cSDH performed under local anesthesia (LA) reduces the risk of postoperative delirium and complications compared to general anesthesia (GA). METHODS: The ABC-SDH trial was a single-center, open-label, phase 2, prospective randomized clinical trial conducted at a tertiary academic medical center between October 2023 and November 2024. Fifty consecutive patients with a confirmed diagnosis of cSDH underwent burr hole craniotomy performed under either LA or GA. Primary outcomes were postoperative delirium (Confusion Assessment Method, CAM) and complications rates until discharge, and the recruitment rate. Secondary outcomes included procedural times and clinical outcome measures at discharge and at 30-day follow-up. RESULTS: LA was associated with a significantly lower rate of postoperative delirium (4% vs. 32%, OR 0.09; 95%CI, 0.01–0.79; p = 0.03; NNT = 4). Complications occurred in 8% (LA) versus 32% (GA) (OR 0.18, 95% CI 0.03–0.96; p = 0.08). LA was also associated with significantly reduced procedural times (139.3 ± 53.0 vs. 196.0 ± 52.1 min; p = 0.002). The severity of complications and functional outcomes were comparable between groups. CONCLUSION: LA was associated with significantly lower rates of postoperative delirium and a shorter periprocedural duration compared to GA in patients undergoing cSDH evacuation. As the first prospective trial to systematically assess the incidence of delirium following burr hole craniotomy for cSDH, the ABC-SDH trial highlights the feasibility and safety of LA in a delirium-prone population. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s13054-026-05913-1.