Hemorrhage Volume and Imaging Recommendations: Factors for Decision Making in the Care of Patients With Perimesencephalic Subarachnoid Hemorrhage

Abstract

BACKGROUND AND OBJECTIVES: Perimesencephalic subarachnoid hemorrhage (pmSAH) has a markedly better prognosis than aneurysmal subarachnoid hemorrhage. Despite advances in noninvasive imaging, the role of repeat digital subtraction angiography (DSA) after negative initial high-quality vascular imaging remains debated. We evaluated the diagnostic yield and procedural risk of DSA in a large bicenter pmSAH cohort. METHODS: We retrospectively analyzed 279 consecutive patients with pmSAH treated at 2 tertiary neurosurgical centers between 1999 and 2021. Demographics, clinical severity, vascular imaging [computed tomography angiography (CTA)/DSA/magnetic resonance angiography], procedure-related complications, and functional outcome (modified Rankin Scale) were assessed. Perimesencephalic blood volume was quantified from initial noncontrast computed tomography when available. RESULTS: The predominant clinical presentation was mild with favorable outcome, with a mean modified Rankin Scale at discharge of 1.07 (SD 1.05). Imaging included CTA in 254 patients (91.0%), DSA in 199 patients (71.3%), and magnetic resonance angiography in 55 patients (19.7%). Vascular pathology was identified in 1 patient (0.4%), detected only after clinical deterioration and repeat DSA. Procedure-related ischemic complications occurred in 7 patients (2.5%), resulting in permanent neurological deficit in 1 patient (0.4%). A volumetric 13-mL pmSAH-threshold (Youden optimal) reliably separated poor from favorable discharge outcome (area under the curve 0.826), with high specificity (0.88) and negative predictive value (0.97), indicating potential value for early clinical decision-making. CONCLUSION: In patients meeting strict pmSAH criteria with negative high-quality CTA, routine repeat DSA seems unjustified given a procedural complication rate that exceeds diagnostic yield. Hemorrhage volume may support early risk stratification but warrants further validation.