Nonaneurysmal convexity subarachnoid hemorrhage

Background: Catheter angiography is performed to exclude aneurysm as the cause of subarachnoid hemorrhage (SAH). Certain categories of SAH however are for the most part nonaneurysmal and the risk of catheter angiography not justified. Primary convexity SAH may be nonaneurysmal and adequately investigated noninvasively. Objective: Determine if primary convexity SAH is nonaneurysmal in origin. Method: Five new cases with primary convexity SAH and seven from the literature are reviewed for etiology, diagnostic studies, and outcome. Results: Diagnostic investigations included catheter angiography in 6 patients, MR in 11 patients, computed tomography (CT) in 10 patients, magnetic resonance angiography/ magnetic resonance venography in 7 patients, CT angiography in 1 patient, and outcome of the 12 patients was benign without subsequent hemorrhage. Conclusion: No case of primary convexity SAH was caused by aneurysm and outcome was benign in all patients, suggesting a noninvasive evaluation is adequate to investigate this condition.