Risk Factors for Pericallosal Artery Aneurysm Rupture Based on Morphological Computer-Assisted Semiautomated Measurement and Hemodynamic Analysis

Background: Although pericallosal artery aneurysms (PAAs) are relatively uncommon, accounting for only 1–9% of all intracranial aneurysms (IAs), they exhibit a considerably high propensity to rupture. Nevertheless, our current knowledge of the risk factors for PAA rupture is still very limited. To fill this gap, we investigated rupture risk factors for PAAs based on morphological computer-assisted semiautomated measurement (CASAM) and hemodynamic analysis.Methods: Patients with PAAs were selected from the IA database in our institute and their baseline data were collected. Morphological parameters were measured in all enrolled patients by applying CASAM. Computational fluid dynamics simulation (CFD) was performed to evaluate the hemodynamic difference between ruptured and unruptured PAAs.Results: From June 2017 to June 2020, among 2141 patients with IAs in our institute, 47 had PAAs (2.2%). Thirty-one patients (mean age 57.65 ± 9.97 years) with 32 PAAs (20 unruptured and 12 ruptured) were included in the final analysis. Comparing with unruptured PAAs, ruptured PAAs had significantly higher aspect ratio (AR), mean normalized wall shear stress (NWSS), and mean oscillatory shear index (OSI) values than the unruptured PAAs (all P < 0.05) in univariate analyses. Multivariable analysis showed that a high mean OSI was an independent risk factor for PAA rupture (OR = 6.45, 95% CI 1.37–30.32, P = 0.018).Conclusion: This preliminary study indicates that there are morphological and hemodynamic differences between ruptured and unruptured PAAs. In particular, a high mean OSI is an independent risk factor for PAA rupture. Further research with a larger sample size is warranted in the future.

Pericallosal Artery Aneurysm: systematic review

Background: Pericallosal artery aneurysms, from A2 to A5 segments of anterior cerebral artery, are uncommon (literature states 2.3-9.2% of brain aneurysms). They have a high mortality rate and tend to rupture easily during exposure. This study was done with the intention of pointing out the described presentations of pericallosal artery aneurysms. Materials and Methods: A systematic review related to pericallosal artery aneurysm was performed in the PubMed, MedLine (Ebsco), LILACS and Scielo databases, using as keywords: “pericallosal artery”, “distal anterior cerebral artery” and “aneurysm”. Results: Pericallosal artery aneurysms are present mainly in patients over 50 years of age (2.1:1 female to male). In younger patients (less than 20 years old) the seizure is the most frequent symptom, while in adults (20-59 years old) it is the thunderclap headache. They commonly present with Hunt & Hess Grade (HH) II. However, 69% presented subarachnoid hemorrhage (SAH), presenting mainly with Fisher 4, which increases the chance of vasospasms. Conclusion: Thus, although the distal anterior cerebral artery (pericallosal) aneurysms display common symptoms, they usually have severe bleeding. Nonetheless, more studies are needed to analyze the epidemiological, demographic and clinical aspects of the pericallosal artery aneurysms