Not Tonight, Darling, I Might Get a Headache

See related article, pages 1878–1882Advances in neuroimaging and an increase in the number of neuroimaging procedures performed have created a new management dilemma. Unruptured intracranial aneurysms (UIA) are found in ≈2% of people undergoing digital subtraction angiography1 and in 0.4% of people undergoing an MRI.2 The best risk management strategy in these patients is not known.Such patients are at increased risk for aneurysmal subarachnoid hemorrhage (SAH), but to know how they might best be managed, we need to understand more about the natural history of UIA, about factors that might provoke rupture, and about the risks and potential successes of intervention. In recent years, the Utrecht group,3 whose most recent work appears in this issue of Stroke , has contributed greatly to our understanding of these issues.The best estimate of the risk of rupture probably comes from the prospective arm of International Study of Unruptured Intracranial Aneurysms (ISUIA),4 which suggests an annual rupture risk of ≈0.1% for aneurysms 10 mm and most are in the anterior circulation.Paradoxically, despite this apparently very low rupture risk, most aneurysmal SAH appear to be attributable to rupture of small anterior circulation aneurysms. The most rational explanation, proposed by Wiebers et al5 and strongly supported by detailed mathematical modeling,6 is that most SAH arises from recently formed rather than long-standing aneurysms, although it is …