Multiphysics coupling numerical simulation of flow‐diverting stents in the treatment of patients with pulsatile tinnitus

Abstract

Patients with pulsatile tinnitus (PT) have unstable treatment effects after resurfacing surgery. Flow‐diverting stents (FDS) are proposed as a potential method for the treatment of PT, but the therapeutic effect is not clear. This study aimed to investigate the efficacy of FDS in the treatment of patients with PT induced by sigmoid sinus diverticulum (SSD) and sigmoid sinus wall dehiscence (SSWD). In addition, we aimed to explore the treatment mechanism of PT. Transient‐state multiphysics coupling numerical simulation method based on computed tomography angiography of five patients was used to clarify the biomechanical and acoustic states before and after FDS placement. FDS was placed to prevent the blood flow from impacting the vessel wall in the SSD and SSWD areas. Low blood flow velocity (<0.0391 m/s), high relative residence time (>10 Pa−1), and low wall shear stress of SSD might lead to thrombosis after FDS placement. The average pressure on the SSWD area of each patient decreased by 13.77%, 18.82%, 29.23%, 19.03%, and 11.20%. The average displacement of the vessel wall on the SSWD area showed acute pulsation and decreased by 15.29%, 14.64%, 30.22%, 41.03%, and 21.28%. The average sound pressure level at the tympanum decreased by 14.01%, 9.33%, 17.66%, 18.88%, and 25.18%, respectively. In brief, FDS was placed to avoid blood flow impacting vessels and reduce the vibration of vessels in the short term, thereby attenuating the degree of PT. The long‐term prognosis was that the SSWD area was blocked after SSD thrombosis. Therefore, FDS might be an effective method for the treatment of PT induced by SSD and SSWD. This study would provide a theoretical basis for the treatment of PT and an exploration of FDS design in the treatment of PT.

Retroauricular/Transcranial Color-Coded Doppler Ultrasound Approach in Junction With Ipsilateral Neck Compression on Real-Time Hydroacoustic Variation of Venous Pulsatile Tinnitus

“…A larger amplitude of the flow sound was detected at segments with a higher flow velocity and pressure gradient. This finding substantiates the therapeutic effect of endoluminal TSS stenting, which targets the reduction of regional flow velocity and relief of the trans -stenotic pressure gradient ( Mu et al, 2021a ). Previous computational studies found that the flow-induced displacement of the vascular wall could generate vibro-acoustic noise from 48.76 to 116.57 dB ( Tian et al, 2017 ; Mu et al, 2021a , b ).…”

“…This finding substantiates the therapeutic effect of endoluminal TSS stenting, which targets the reduction of regional flow velocity and relief of the trans -stenotic pressure gradient ( Mu et al, 2021a ). Previous computational studies found that the flow-induced displacement of the vascular wall could generate vibro-acoustic noise from 48.76 to 116.57 dB ( Tian et al, 2017 ; Mu et al, 2021a , b ). The amplitude of the vibro-acoustic sound surpassed that of the hydroacoustic source when the volume and surface contributions were juxtaposed ( Hsieh et al, 2022 ).…”

Therapeutic Validation of Venous Pulsatile Tinnitus and Biomaterial Applications for Temporal Bone Reconstruction Surgery Using Multi-sensing Platforms and Coupled Computational Techniques

“…According to the current in vivo displacement sensing results, the major frequency of flow-induced vascular displacement was below the audible frequency range. This outcome contradicts the current coupled CFD outcomes and a few in vitro/computational studies (Tian et al, 2019;Mu et al, 2021). There are two plausible reasons for this divergence: first, the sigmoid sinus vascular wall is tightly fixated onto the concave surface of the sigmoid plate connected by the dura mater situated in between, which can be difficult to reproduce using experimental and computational methods.…”

“…As the sound wave pressure dampens due to surrounding human anatomical structures, the acquisition of the absolute amplitude of PT in vivo can be rather arduous. However, the coupled computational fluid dynamics (CFD) technique has recently succeeded in revealing hydroacoustic and flow fluid-structure interaction details of PT but requires accurate establishment of boundary conditions (Tian et al, 2017;Hsieh Y.-L. et al, 2021;Mu et al, 2021). Therefore, continuous refinements on applying in vivo sensed mechanical characteristics of realistic anatomical structures and biomaterials are warranted, to support computational simulations and quantitatively verify surgical efficacy.…”

“…As dehiscence forms, the sound wave originating from the intrasinus vascular flow is hypothesized to permeate through the thinned/dehiscent bony plate, reaching the inner ear through subspaces of the mastoid bone via the air-conduction transmission pathway ( Eisenman, 2011 ; Bhatnagar et al, 2020 ). However, some authors have reported the vibroacoustic generation of PT due to displacement of the vascular wall as a causative factor of PT ( Tian et al, 2019 ; Mu et al, 2021 ). Despite the dichotomous view of PT acoustic origination, both hypotheses have postulated that PT is transmitted by air, and the bone-conduction transmittance is considered less significant ( Eisenman et al, 2018 ; Bhatnagar et al, 2020 ).…”