Subarachnoid Hemorrhage with a Cerebral Aneurysm not Recognized at Conventional Angiography: A Retrospective Study

To investigate the possible causes of a false-negative initial cerebral digital subtract ionangiography (DSA) of aneurysmal subarachnoid hemorrhage (SAH). Six initially unrecognized ruptured aneurysms were reviewed from among approximately 160 aneurysmal SAH cases collected from the medical records. The standard angiographic procedure and findings on repeat DSA were used to identify the possible causes. The initial DSA was reviewed and the false-negative impression resulted from an initial overlooking with or without incomplete procedure (4/6), presumed thrombosis or vasospasm with no recognized aneurysm, even when reviewed retrospectively (3/6), and the presence of a blister aneurysm (1/6). Two of the six cases had multiple causes. Whenever the DSA is negative in a patient strongly suspected of an aneurysmal SAH, the three above-mentioned causes should be considered and repeat DSA in the proper clinical setting is recommended.