Transient Analysis of Vortical Flows in Sigmoid Sinus Diverticulum Using Computational Fluid Dynamics

Sigmoid sinus diverticulum is a common anatomical anomaly found in patients with venous pulsatile tinnitus (PT). This study aims to study the intradiverticular flow pattern and its clinical influence using transient computational fluid dynamics (CFD). A 29-year-old female with persistent right-sided PT using high-resolution computed tomography. Based on her magnetic-resonance angiography, the patient-specific three-dimensional geometry was reconstructed using Mimics 19.0 and 3-Matics 11.0 (Materialise Technologies). The time-dependent simulation was performed using the commercial software Fluent 13.0 (ANSYS Inc., USA). Notwithstanding the noticeable multi-directional flow, CFD simulation showed that the intradiverticular flow kinetic energy was comparatively lower in comparison to the medial portion of mainstream sinus flow. It was also shown that the flow stagnation and regurgitation occurred in the diverticulum, which the flow characteristics were congruent with current imaging modalities. Our CFD results provide deeper insights into intradiverticular fluid mechanics and support current clinical discovery that a diverticulum per se may not be a dominant factor causing audible PT owing to the relatively low intradiverticular turbulent kinetic energy.