Influence of the correct placement of external ventricular drainage on puncture channel bleeding in patients with aneurysmal subarachnoid hemorrhage

While ventriculostomy-associated hemorrhages are well-documented in spontaneous subarachnoid hemorrhage (SAH), the impact of external ventricular drainage (EVD) placement accuracy on puncture channel bleeding (PCB) remains underexplored. This study investigates whether incorrect EVD trajectory is associated with increased PCB risk in aneurysmal SAH (aSAH) patients and evaluates the influence of peri-interventional antiplatelet and anticoagulation therapy on these events. We analyzed 127 patients with aSAH who underwent EVD placement and aneurysm treatment between September 2021 and June 2025 from our prospectively maintained registry. EVD positioning was classified as correct (ipsilateral intraventricular) or incorrect (e.g., contralateral or intraparenchymal). PCB was defined as hemorrhage along the catheter tract on post-procedural CT. Data on antiplatelet/anticoagulant use and clinical outcomes were collected. Functional and cognitive outcomes were assessed using the modified Rankin Scale (mRS) and Montreal Cognitive Assessment (MoCA), respectively. PCB occurred in 20% of patients. Incorrect EVD placement was strongly associated with PCB, occurring in 56% of malpositioned catheters compared with 15% of correctly positioned catheters (p < 0.001). In multivariable logistic regression, incorrect EVD placement remained the only independent predictor of PCB (OR 7.8, 95% CI 2.45-26.35; p < 0.001). Neither pre-admission antiplatelet or anticoagulation therapy nor peri-interventional antiplatelet therapy was significantly associated with PCB (all p = 0.5). In univariate analysis, functional outcome at discharge and at 3 months did not significantly differ between groups (p = 0.43 and p = 0.28, respectively). However, in multivariable analysis adjusting for age and clinical severity, PCB was independently associated with a lower likelihood of favorable functional outcome both at discharge (OR 0.19, 95% CI 0.04-0.70; p = 0.02) and at 3 months (OR 0.10, 95% CI 0.01-0.75; p = 0.03). Cognitive outcome (MoCA) was not significantly affected.. Incorrect EVD placement is a strong and independent risk factor for puncture channel bleeding in patients with aSAH, whereas antiplatelet and anticoagulation therapy did not significantly influence bleeding risk. Although PCB was not associated with cognitive impairment, it was independently associated withworse functional outcome after adjustment for confounders. These findings highlight the critical importance of accurate catheter trajectory in reducing procedure-related complications and improving overall outcome in neurovascular care.