Abstract
A 62-year-old woman, suffering from a sudden onset headache, was referred to our hospital. Computed tomography (CT) revealed a subarachnoid hemorrhage, but neither CT angiography nor digital subtraction angiography (DSA) demonstrated aneurysms on day 1. A distal anterior cerebral artery aneurysm was detected by repeated DSA on day 33, and direct surgery was performed on day 38. Because the aneurysm contained a firm thrombus in the lumen, blood flow within the aneurysm could not be observed by intraoperative indocyanine-green video angiography. Neck clipping was achieved after removal of the thrombus by incising aneurysmal dome. Intraaneurysmal thrombus demonstrated angiogenesis, indicating recanalization. Histopathological findings, including the formation of intraaneurysmal thrombus with recanalization, explain a temporal change of angiographical appearance of the present aneurysm, which may represent the initial stage of development of large/giant thrombosed aneurysms due to repeated thrombosis and recanalization.
