High-Frequency wall vibration correlates with growth of a vertebrobasilar dolichoectatic Aneurysm: A case study

Vertebrobasilar dolichoectatic aneurysms (VBDAs) are a rare cerebrovascular condition with poorly understood pathophysiology. While complex flow-induced stresses are believed to influence aneurysm initiation, progression, and rupture, previous computational VBDA or more broadly cerebral aneurysm studies have focused primarily on time-averaged wall shear stress at a single time point. In this study, we investigate a broader range of mechanical stimuli using longitudinal data to explore their association with VBDA growth and remodeling, which may lead to its rupture. We performed high-fidelity/resolution fluid-structure interaction simulations of the posterior circulation in a patient with VBDA using medical images from three time points. We computed stresses at and within the wall, with the latter decomposed into low-frequency (pulsations) and high-frequency (vibrations) components. We examined whether pulsations, vibrations, or conventional hemodynamic metrics independently contributed to VBDA growth. At the first time point, inflow jets from the left and right vertebral arteries collided, creating local flow instabilities and associated wall vibrations above the vertebrobasilar junction. Within this region, spectrograms, showing the evolution of vibration frequency, revealed several narrow band vibration peaks between 50 and 150 Hz. Only regions of high vibration amplitude correlated with VBDA growth; conventional hemodynamic metrics and pulsations showed no such association. These results were broadly consistent across the second and third time point, during which further growth of the VBDA was confirmed. This case study demonstrates a qualitative spatial-temporal association between flow-induced high-frequency wall vibrations and growth of the VBDA, supporting the hypothesis that wall vibrations may act as a mechanobiological stimulus.