Location and Size of Ruptured Intracranial Aneurysm and Serious Clinical Outcomes Early after Subarachnoid Hemorrhage: A Population-Based Study in Australasia

Abstract

Background: It is uncertain whether the location and size of a ruptured intracranial aneurysm (IA) independently influences the outcome of subarachnoid hemorrhage (SAH). Objective: To determine the independent relationship of location and size of a ruptured IA with serious clinical outcomes after SAH in an Australasian population-based study. Methods: From 432 first-ever cases of primary SAH registered prospectively over 12 months in 4 Australasian cities between 1995 and 1998, the demographics, clinical features, risk factors and results of investigations were obtained, including the location and size of any ruptured IA as assessed by cerebral angiography, computed tomography and/or magnetic resonance imaging. Location was classified as either anterior (i.e. anterior communicating artery, internal carotid artery and middle cerebral artery) or posterior circulation (i.e. posterior communicating artery, posterior inferior cerebellar artery, basilar artery and vertebral artery), and size was classified as <5, 5–9 and ≧10 mm. Outcomes recorded during hospitalization were rebleeding, delayed ischemia, hydrocephalus, residual neurological impairment and in-hospital death. Logistic regression analysis was used to evaluate the effects of IA location and size on outcome, independent of other potential prognostic factors. Data are reported with odds ratios (OR) and 95% confidence intervals (CI). Results: IA location and size were confirmed separately in 299 and 252 patients, respectively. Patients with a posterior circulation IA had a lower rate of rebleeding than those with an anterior circulation IA (adjusted OR: 0.11; 95% CI: 0.02–0.87), but otherwise there was no significant relationship between IA location and outcome. Patients with a larger ruptured IA had higher risks of rebleeding (p = 0.02 for trend) and in-hospital death (p = 0.001) after controlling for age, sex, ethnicity, location of the ruptured IA and neurosurgical intervention. Conclusion: IA location in the posterior circulation was associated with a lower risk of rebleeding than IA in the anterior circulation. A larger IA size was associated with higher risks of rebleeding and in-hospital death.

Aneurysm diameter as a risk factor for pretreatment rebleeding: a meta-analysis

“…Review of the abstracts left us with 26 studies for the full-text evaluation. [3][4][5][6]9,10,[18][19][20][22][23][24][25][27][28][29][30][31]33,[35][36][37]39,41 Ten studies were excluded because they did not evaluate aneurysm diameter as a risk factor for rehemorrhage rate. 4,6,9,18,22,24,29,36,39,41 Two other articles were excluded because one was a review and the other was an editorial.…”

“…5,19,20,27,28,30,35 In total we identified 9 studies that met our inclusion criteria. 3,10,19,23,27,28,33,37,41 Clinical and/or radiological definitions of rebleeding were given in 8 studies and these are listed in Table 2. Only 1 study reported the median time to rebleeding and the median time to aneurysm repair.…”

“…In 5 studies, however, the quality was rated down because of serious limitations: Adjustment of the rebleeding rate for the time after the initial hemorrhage was not performed, or consecutive series were not reported. 10,19,23,33,37 data analysis Seven of 9 studies provided core data, making calculation of the OR possible. 10,19,23,28,33,37,41 Almost all of the studies used 10 mm as the cutoff point for aneurysm size among others classes, with only 1 study using 7 mm (Table 4).…”

“…In recent years, several risk factors, such as hypertension and the location and size of the aneurysm, have been shown to be associated with rebleeding. 9,10,19,28,37 Biomechanical studies have indicated that cerebral aneurysmal rupture occurs when there is a decrease in the ratio of the artery wall thickness to the radius of the aneurysm. 7 This concept might explain the possible relationship between aneurysm diameter and the risk of rebleeding.…”

Prognostic factors in patients underwent aneurysmal clipping surgery due to spontaneous subarachnoid hemorrhage

“…Shiue et al (33) point out that the size of a ruptured aneurysm is an important determinant of outcome in SAH, and should be used as a prognostic parameter in directing management. Yates continuity correction test, p<0.01** in the logistic regression analysis, an aneurysm size above 7 mm was found to be an independent risk factor for mortality but findings were showed the number of aneurysms did not differ significantly in terms of mortality.…”