The Increase of Rupture of Unruptured Intracranial Aneurysm in SAH Population

Abstract

Japan now has a large number of centers that can perform magnetic resonance imaging. Further, the brain check-up system has also improved considerably. Thus, many unruptured intracranial aneurysms (UIA) have been diagnosed recently, and some of these are treated in an evidence-based manner. However, with the increase in the diagnosis of UIA, cases of rupture of UIA are supposed to be increasing.
To test this hypothesis, we compared cases of rupture of UIA with subarachnoid hemorrhage (SAH) treated at Tokyo Dental College Ichikawa General Hospital between January 2002 and December 2006 (the early period) with those between January 2007 and December 2011 (the latter period). UIA was previously diagnosed in 1 of 100 SAH cases (1.0%) in the early period and in 11 of 132 SAH cases (8.3%) in the latter period. This difference was significant.
We evaluated the following risk factors in patients with rupture of UIA in both groups: UIA location, size, bleb, UIA multiplicity, history of hypertension, habit of smoking, and family history of SAH. Most patients in both groups had several of the evaluated risk factors, and all cases of rupture occurred in female patients in the both periods. On the other hand, two patients in the latter group presented with only one risk factor.
Our results suggest that the number of cases of rupture of previously diagnosed UIA have increased recently. To prevent the occurrence of rupture, we recommend that female UIA patients with several risk factors be treated with the obliteration of UIA. Further, clinicians should be alert to the risk of rupture in patients with only one risk factor, and periodic follow-up might be essential for such cases.