Abstract
Background and Objectives: The asymmetrical vertebral artery (VA) flow and diameter are common findings, which can result in an asymmetrical blood flow in the basilar artery (BA), leading to bending of the artery over time. This study investigated whether the variation of the different vertebrobasilar morphological indices that influence flow characteristics might be inherited. Materials and Methods: We analyzed 200 cerebral magnetic resonance imaging (MRI) scans of healthy Caucasian twins (100 pairs) who underwent time-of-flight MRI. From the scans, we reconstructed the 3D mesh of the posterior circulation from the start of the V4 segment to the basilar tip and subsequently analyzed the morphology of the vertebrobasilar system. The phenotypic covariances of the different morphological parameters were decomposed into heritability (A), shared (C), and unshared (E) environmental effects. Results: 39% of the twins had left dominant VA, while 32.5% had right dominant. In addition, 28.5% were classified as equal. The vertebral artery V4 segment diameter, curvature, and tortuosity were mainly influenced by shared (C) and unshared (E) environmental factors. A moderate heritability was found for the BA length (A: 63%; 95% CI: 45.7–75.2%; E: 37%; 95% CI: 24.8–54.3%) and volume (A: 60.1%; 95% CI: 42.4–73.2%; E: 39.9%; 95% CI: 26.8–57.6%), while the torsion of both arteries showed no heritability and were only influenced by the unshared environment. Conclusions: The length and volume of the BA show a moderate genetical influence. However, most of the measured morphological indices were influenced by shared and unshared factors, which highlight the role of the ever-changing hemodynamic influences shaping the geometry of the vertebrobasilar system.
Highlights
A stroke remains the second most common cause of death in the European Union, and it is the leading cause of disability amongst adults
20% of all strokes occur in the posterior region of the brain, which is supplied by the vertebrobasilar system, with high mortality and morbidity [2]
No significant difference was observed between the MZ and DZ groups regarding anthropometric variables and risk factors
Summary
A stroke remains the second most common cause of death in the European Union, and it is the leading cause of disability amongst adults. Higher levels of the intra-pair correlation between MZ pairs compared to DZ twins indicate a greater genetic influence on a phenotype, while a greater cross MZ and DZ twin similarity suggests that the variance is due to shared environmental factors. The phenotypic variance of the different morphological parameters was decomposed into heritability (A), shared (C), and unshared (E) environmental effects (ACE analysis).
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