Genetic and environmental impacts influencing neurovascular diseases, such as cerebral aneurysms (CAs), are uniquely investigated by studying monozygotic twins (MTs). We compared arterial configurations and hemodynamic indicators encountered in cerebral arteries and CAs discovered in a rare pair of MTs (i.e., twin A and twin B) with only twin A experiencing CA rupture. The twins share identical facial anatomies, geographic location, risk factors, and heights, with only minor differences in weights (twin A 87.3 kg vs. twin B 70.3 kg). The MTs were discovered after twin A presented in 2021 with a ruptured CA located at the right anterior cerebral artery (ACA) bifurcation. Twin B was identified by the treatment team to be high risk for a similar fate but was discovered to not have any symptoms. Both twins agreed to have their cerebral vascular anatomy studied and participated in research investigations. Twin A was found to have an absent first order left ACA division with associated branches arising from the right anterior circulation, while twin B had an intact circle of Willis, but had an undiscovered, unruptured, CA located at the bifurcation of the left ACA first order division. With permission, we analyzed the anatomical differences of the cerebral arteries in the MTs, including corresponding arterial dimensions and morphologies. Despite the expected genetic similarities, morphological comparisons of the MTs show the size and shape of cerebral arteries to have significant differences with most regions in the main internal carotid artery (ICA) in twin A being larger than the dimensions in twin B, from 2.23% to 25.86% depending on specific compared locations. Projective profiles in three perspective views also did not match well between the twins. Subsequently, an experimentally validated computational fluid dynamics (CFD) model was employed to further explore the differences in blood flow patterns in the rebuilt cerebral arteries of the MTs, which is believed as an essential factor for the CA pathophysiology. CFD results indicate the MTs have some random hemodynamic similarities (e.g., time-averaged pressure distributions (~13400 Pa), and oscillatory shear index (OSI) (0~0.49), but present significant differences in specific local arteries due to morphological variances. Specifically, the difference in the volumetric blood flow rate in corresponding arteries between the MTs is from 16% (smallest) in anterior choroidal artery (AChA) to 221% (largest) in the ophthalmic artery (OphA), varying with specific compared arteries. Also, differences in the registered hemodynamic indicators, such as the maximum time-averaged wall shear stress (53.6 Pa vs. 37.8 Pa), and local OSI distributions were observed between the MTs. The findings revealed that morphological variations in MTs could be generated by embryological and environmental factors, thus assuming MTs share the identical morphology in neurovascular systems may lead to significant errors in hemodynamics quantifications and risk stratification.
Disclosures L. Bramlage: None. H. Yi: None. Z. Yang: None. B. Ludwig: None.
Statistics from Altmetric.com
If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.