Abstract
We report the case of a patient who suffered from subarachnoid hemorrhage (SAH) from “de novo aneurysm” even though there had been no abnormal findings on head magnetic resonance imaging (MRI) and magnetic resonance angiography (MRA) in the past. A 69-year-old woman had undergone head MRI and MRA at our hospital 6 years previously, but there were no abnormal findings. She later suffered from severe headache, and computed tomography of the head at second admission showed SAH. MRA and digital subtraction angiography showed de novo aneurysm at the right distal anterior cerebral artery bifurcation, so aneurysmal clipping was performed. The postoperative course was good. Although some reports about de novo aneurysm have been published, almost all of them were about cases of de novo aneurysm formation following at another site. Ruptured de novo aneurysm with no abnormal findings in the past is very rare. Because the risk of de novo aneurysm formation remains, long-term follow-up is needed.
