Purpose: Diagnostic workup in patients with angiographically negative subarachnoid hemorrhage (SAH) remains controversial. We discuss the relevance of bleeding patterns on CT as they pertain to the prediction of angiographic results.
Materials and methods: We compared bleeding patterns on 112 CTs of patients with non-aneurysmal subarachnoid hemorrhage (non-ASAH) and 104 CTs of patients with aneurysmal SAH (ASAH) taken within 48 hours according to a CT-based grading system (Type 0 - 4).
Results: Bleeding patterns differed between ASAH and non-ASAH patients (p < 0.0001). Non-ASAH patients had no or prepontine blood (type 0 + 1) in 40% of cases, extension into the medial (type 2) or lateral (type 3) Sylvian fissure in 60% of cases and no intracerebral hemorrhage (type 4). All type 0 and 1 patients had negative initial and repeat angiographies.
Conclusion: A CT classification of bleeding patterns helps to predict angiographic results. Digital subtraction angiography (DSA) should remain the gold standard as it allows detection non-aneurysmal bleeding sources at low-risk. Repeat angiography may be omitted in the case of type 0 and 1 bleeding if a complete, high quality DSA was obtained initially.
Georg Thieme Verlag KG Stuttgart, New York.