Introduction: When subarachnoid hemorrhage (SAH) is encountered in the setting of multiple intracranial aneurysms, hemorrhage pattern is generally the primary indicator of the ruptured lesion. When the pattern is not definitive, rupture site determination typically relies on angiographic features such as size, morphology and location. We examined the frequency with which such features lead to misidentification of the ruptured lesion, subsequently determined by open microsurgical evaluation.
Methods: SAH cases that proceeded to craniotomy between January 1, 2004 and August 15, 2014 were reviewed, and cases with multiple intracranial aneurysms were identified. Initial head CT scans were reviewed to determine whether the SAH pattern was definitive for the source aneurysm. Those with “non-definitive” hemorrhage patterns were blindly evaluated by reviewing the characteristics of the aneurysms on angiography, and the original presumption of rupture site was also recorded. Operative reports were then reviewed to confirm or refute the imaging-based determination of ruptured aneurysm.
Results: 531 SAH cases undergoing craniotomy were identified; 151 had multiple aneurysms. 80 (53%) had “non-definitive“ hemorrhage patterns on initial CT. Of the 71 with definitive bleed patterns, all had the assumed rupture site confirmed to be accurate at the time of surgery. In contrast, 14 (17.5%) of the cases with non-definitive hemorrhage patterns on CT had discordance between the assumed source on original or secondary radiological review, and the actual intraoperative determination of the ruptured aneurysm.
Conclusions: SAH cases with multiple aneurysms frequently demonstrate a bleed pattern that does not clearly delineate the source aneurysm. Morphological features cannot reliably be used to determine rupture site in these cases. Microsurgical clipping, confirming obliteration of the ruptured lesion, is warranted in this setting, unless all lesions can be contemporaneously treated with endovascular embolization.
Patient Care: Change management determination in the setting of subarachnoid hemorrhage with multiple intracranial aneurysms.
Learning Objectives: To determine the frequency of misidentification of source aneurysm in the setting of subarachnoid hemorrhage with multiple intracranial aneurysms.