Aneurysmal subarachnoid hemorrhage: Role of computerized tomography for correct prediction of the ruptured aneurysm site

Objective: To investigate if the intracisternal distribution of subarachnoid hemorrhage (SAH) following aneurysm rupture allows the correct prediction of the symptomatic aneurysm site. Methods: Ninety-nine consecutive patients with acute SAH and angiographically proven aneurysm were included into the study. The parent vessel of the diagnosed aneurysms were the anterior communicating artery (ACoA) in 38 patients, the middle cerebral artery (MCA) in 26 patients, the internal carotid artery (ICA) in 25 patients, the pericallosal artery (A2) in 5 patients, the basilar artery (BA) in 4 patients and the vertebral artery (VA) in 1 patient. In 21 patients, an additional asymptomatic aneurysm was diagnosed. The initial computerized tomography (CT) scans of the 99 patients were given to 2 experienced vascular neurosurgeons, who were blinded for the angiography findings. The 2 investigators had to predict the site of the ruptured aneurysm. Results: Investigator 1 correctly predicted the aneurysm site in 56 (57%), investigator 2 in 59 of the 99 patients (60%). Investigator 1 correctly identified 81% of the MCA aneurysms, and investigator 2 74% of the ACoA aneurysms. However, in only 46 of the 99 patients (47%), the aneurysm site was correctly predicted by both investigators together. Conclusion: The results indicate, that the distribution of the subarachnoid blood as shown on the first CT scan after aneurysm rupture barely allows to predict the symptomatic aneurysm site. Thus, neurosurgical decision making (identification of the ruptured aneurysm in patients with multiple aneurysms; surgical exploration in patients with non-perimesencephal SAH, but negative angiography) should not rely on the first CT scan after SAH.