Abstract: Objective To explore the relationship between the size and location of the aneurysm after subarachnoid hemorrhage (aSAH) and its clinical classification. Methods A retrospective study was performed in patients with aSAH from January 1, 2008 to December 31, 2014. The relevant clinical data were collected including age, gender, aneurysm size, location, and Hunt-Hess (H-H) classification. The aneurysms were classified by size (A group d＜5.00 mm, B group 5.00 mm≤d＜10.00 mm, C group d≥10.00 mm), location and H-H classification according to the results of CT, digital subtraction angiography (DSA), and magnetic resonance angiography (MRA). The relationship between size, position of aneurysm and H-H classification was observed and analyzed. Results There were 750 cases included in this study, with average age (56.14±11.88), male 292 and female 458. The total number of aneurysms was 903, and the number of multiple aneurysms was 91 (12.13%). There was one case with multiple aneurysms that can be included in A, B and C groups. There were two cases with multiple aneurysms that can be included in A and B groups, two cases can be included in A and C groups, and three cases can be included in B and C groups. The number of aneurysms and the ratios of groups A, B and C were 20 (3.9%), 12 (3.8%), 5 (7.5%), 70 (13.6%), 39 (12.2%), 10(14.9%), 2 (0.4%), 4 (1.3%), 2 (3.0%), 165 (32.0%), 94 (29.4%), 6(9.0%), 130 (25.2%), 90 (28.1%), 6 (9.0%), 17 (3.3%), 11 (3.4%) and 2 (3.0%) for the location in the anterior cerebral artery, the middle cerebral artery, the posterior cerebral artery, the internal carotid artery, the anterior communicating artery, the posterior communicating artery, and the vertebral basilar artery, respectively. The number of aneurysms and the ratios of H-H
classificationⅠ， Ⅱ， Ⅲ， Ⅳand Ⅴin groups A, B and C were 48 (9.3%), 45 (14.1%), 12 (17.9%), 228 (44.2%), 150 (46.9%), 14 (20.9%), 68 (13.2%), 54 (16.9%), 30 (44.8%), 142 (27.5%), 43 (13.4%), 9 (13.4%), 30 (5.8%), 28 (8.8%) and 2 (3.0%). There was a negative correlation between the size of aneurysm and the H-H grade (rs=-0.075, P=0.024). Conclusion The anterior communicating artery and posterior communicating artery are high-risk areas for smaller aneurysms. The internal carotid artery is high-risk areas for larger aneurysms. The size of aneurysm is negatively correlated with H-H classification.

Key words: subarachnoid hemorrhage, aneurysm, aneurysmal subarachnoid hemorrhage, Hunt-Hess