Computational Fluid Dynamics Simulation of Hemodynamic Alterations in Sigmoid Sinus Diverticulum and Ipsilateral Upstream Sinus Stenosis After Stent Implantation in Patients with Pulsatile Tinnitus.
OBJECTIVE
To investigate the relationships between upstream venous sinus stenosis and pulsatile tinnitus (PT), and to assess the correlation with diverticulum growth and the effectiveness of stent implantation.


METHODS
Patient-specific geometric models were constructed using computed tomography venography images from a patient with PT, with sigmoid sinus diverticulum, and with upstream transverse sinus stenosis, in whom stenting of the upstream sinus stenosis alone achieved complete remission of PT. Computational fluid dynamics simulation based on this patient-specific geometry was performed using commercially available finite element software (ANSYS-14) to qualitatively and quantitatively compare the flow velocity, flow rate, velocity vector, pressure, vorticity, and wall shear stress on the affected side transverse and sigmoid sinuses, before and after stent implantation.


RESULTS
Stenting improved the flow direction and magnitude. After stenting, the flow pattern became smoother and more regular. High-speed blood flow at the level of the diverticulum neck was confined to a smaller area, and its direction changed from approximately perpendicular to the diverticular dome to the distal side of the diverticular neck. The diverticulum showed obvious flow reduction, with decreases of 80.7%, 68.7%, 96.1%, and 91.3% in peak velocity, inflow rate, pressure gradient, and peak vorticity, respectively. The abnormally low wall shear stress at the dome of diverticulum was eliminated.


CONCLUSIONS
Our findings strongly support a major role of diverticulum stenosis before in PT development and suggest that such stenosis is a causative factor of diverticulum growth. They also confirm the effectiveness of stent implantation for the treatment of PT.
['Han|Yanjing|Y|', 'Yang|Qingqing|Q|', 'Yang|Zeran|Z|', 'Xia|Jun|J|', 'Su|Tianhao|T|', 'Yu|Jianan|J|', 'Jin|Long|L|', 'Qiao|Aike|A|']
D015901:Angiography, Digital Subtraction D001783:Blood Flow Velocity D001794:Blood Pressure D002533:Cerebral Angiography D000072226:Computed Tomography Angiography D003198:Computer Simulation D003251:Constriction, Pathologic D003392:Cranial Sinuses D004240:Diverticulum D057510:Endovascular Procedures D006439:Hemodynamics D006801:Humans D057446:Hydrodynamics D008875:Middle Aged D010690:Phlebography D015607:Stents D013314:Stress, Mechanical D014012:Tinnitus D054064:Transverse Sinuses
Computational fluid dynamics Sigmoid sinus diverticulum Sinus stenosis Stent implantation Pulsatile tinnitus