Transulnar Access for Intra-Operative Angiography During Prone Cerebrovascular Surgery

Introduction/Purpose Intra‐operative cerebral angiography enables real‐time visualization of vascular anatomy and immediate verification of complete lesion resection during open cerebrovascular surgery. Prone positioning for posterior fossa and cervical spine approaches creates anatomical barriers to conventional transfemoral and transradial access routes, obstructing groin and wrist accessibility. Transulnar access (TUA) offers optimal ergonomics in prone patients because the ulnar artery becomes superficially positioned when arms are extended with palms down. Cardiovascular studies demonstrate TUA equivalence to transradial approaches, yet neurovascular applications remain underexplored. We present the first series examining prone TUA for intra‐operative cerebral angiography. Materials/Methods We retrospectively analyzed 8 consecutive patients undergoing prone cerebrovascular surgery with TUA‐guided intra‐operative angiography over 36 months (April 2020‐April 2023). Primary endpoints included technical success rate, procedural completion via TUA alone, and access‐site complications. Under ultrasound guidance, we punctured the ulnar artery 1‐3cm proximal to the pisiform bone using 21‐gauge needles, advancing 5‐French sheaths after confirming arterial flow. Following anti‐spasmolytic administration (heparin 2000u, nitroglycerin 200mcg, verapamil 5mg), patients were positioned prone in Mayfield fixation. We documented ulnar artery diameter, fluoroscopy duration, contrast volume, radiation exposure, and complications including hematoma, pseudoaneurysm, ischemia, and neuropathy. Results All 8 patients achieved successful intra‐operative angiography via TUA without requiring alternative access sites. The cohort comprised 6 arteriovenous malformations (4 occipital, 1 vermian, 1 high cervical) and 2 dural arteriovenous fistulas (1 occipital, 1 cervicomedullary), with 7 males and 1 female with mean age 54.3±16.7 years. Six procedures utilized left‐sided access while two employed right‐sided approach. Mean ulnar artery diameter measured 2.4±0.35mm via ultrasound evaluation. Procedural metrics demonstrated mean fluoroscopy time of 7.5±2.8 minutes, contrast volume of 51.3±24.2mL, and radiation dose of 3235.8±3399.4 mGy*cm. Zero access‐site complications occurred throughout the series, with no observed hematomas, pseudoaneurysms, peripheral ischemia, or nerve injuries during immediate postoperative monitoring. Conclusion Prone TUA provides a reliable and safe alternative for intra‐operative cerebral angiography when conventional access routes are anatomically compromised. The technique achieved 100% procedural success without complications across diverse posterior circulation pathologies. TUA's ergonomic superiority in prone positioning with unobstructed catheter access and preserved sterile fields addresses fundamental limitations of transfemoral and transradial approaches during posterior fossa procedures. As the first reported series of prone ulnar access for angiographic interventions, these findings establish TUA as a valuable technique warranting integration into neurovascular practice for prone surgical cases.