School of Life Science and Bioengineering, Beijing University of Technology, Beijing 100124, China.
Department of Radiology, Beijing Friendship Hospital, Capital Medical University, Beijing 100050, China.
Comput Methods Programs Biomed. 2020 Jul;190:105373. doi: 10.1016/j.cmpb.2020.105373. Epub 2020 Jan 31.
Sigmoid sinus wall anomalies (SSWA) are a common pathophysiology of pulsatile tinnitus (PT) and usually treated by sigmoid sinus wall dehiscence (SSWD) resurfacing surgery. However, symptoms of tinnitus remain unrelieved after surgery in some patients with PT, and even new tinnitus appears. The cause of the difference in therapeutic effects is unclear. In this study, eight patient-specific SSWA geometric models were reconstructed on the basis of computed tomography angiography, including four cases of postoperative rehabilitation (group 1, 1-4 cases) and four cases of non-rehabilitation (group 2, 5-8 cases). Transient-state computational fluid dynamics (CFD) was performed to clarify the SS blood flow pattern and hemodynamic states. The wall pressure distribution on SSWA area, pressure difference, and flow pattern in SS were calculated to evaluate the hemodynamic changes of rehabilitation and non-rehabilitation patients before and after surgery. The difference of hemodynamics between these patients was statistically analyzed. The accuracy of CFD simulation was evaluated by cross validating the numerical and particle image velocimetry experimental results. Results showed that the SSWA area in patients with PT was loaded with high pressure. No difference was found in the hemodynamic characteristics between the two groups pre- and postoperation. When the average pressure (P) and time-average P (TAP) on the SSWA area were studied, the TAP difference pre- and postoperation between the two groups was found significant (p = 0.0021). The TAP difference had a negative change in postoperative rehabilitation patients (case 1, -44.49 Pa vs. case 2, -15.85 Pa vs. case 3, -25.88 Pa vs. case 4, -16.58 Pa). The postoperative TAP of non-rehabilitation patients was higher than the preoperative one (case 5, 24.70 Pa vs. case 6, 28.56 Pa vs. case 7, 5.81 Pa vs. case 8, 13.04 Pa). The velocity streamlines in the SS with rehabilitation became smoother and more regular than that without rehabilitation. By contrast, the velocity streamlines in SS without rehabilitation showed increased twisting and curling. No difference was found in time-average volume-averaged vorticity (TAVV) between the two groups. Therefore, the high pressure of the vessel wall on SSWA area was one of the causes of PT. The variation of SSWA wall pressure difference before and after PT was the cause of the difference in therapeutic effects after SSWD resurfacing surgery. In patients with SSWA, disordered blood flow in SS was another cause of PT. SSWD repair may relieve tinnitus to some extent, but blood flow disorders may still arise.
乙状窦壁异常（SSWA）是搏动性耳鸣（PT）的常见病理生理学改变，通常采用乙状窦壁重建术（SSWD）进行治疗。然而，部分 PT 患者术后耳鸣症状仍未缓解，甚至出现新的耳鸣。导致这种治疗效果差异的原因尚不清楚。本研究基于 CT 血管造影术重建了 8 例患者特有的 SSWA 几何模型，包括 4 例术后康复患者（1-4 例，为组 1）和 4 例未康复患者（5-8 例，为组 2）。采用瞬态计算流体动力学（CFD）方法阐明 SS 血流模式和血流动力学状态。计算 SSWA 区域壁面压力分布、压力差和 SS 内的流型，以评估 SSWD 修复前后康复和非康复患者的血流动力学变化。对这些患者的血流动力学差异进行了统计学分析。通过将数值和粒子图像测速实验结果进行交叉验证来评估 CFD 模拟的准确性。结果表明，PT 患者的 SSWA 区域承受着高压。术前和术后两组的血流动力学特征无差异。当研究 SSWA 区域的平均压力（P）和时均压力（TAP）时，发现两组术后 TAP 差异有统计学意义（p=0.0021）。术后康复患者的 TAP 呈负值变化（病例 1，-44.49 Pa；病例 2，-15.85 Pa；病例 3，-25.88 Pa；病例 4，-16.58 Pa）。而非康复患者的术后 TAP 高于术前（病例 5，24.70 Pa；病例 6，28.56 Pa；病例 7，5.81 Pa；病例 8，13.04 Pa）。康复组 SS 内的速度流线比非康复组更平滑、更规则。相比之下，非康复组 SS 内的速度流线显示出更多的扭曲和卷曲。两组间时均体积平均涡量（TAVV）无差异。因此，SSWA 区域血管壁的高压是 PT 的原因之一。PT 后 SSWA 壁压力差的变化是 SSWD 表面重建术后疗效差异的原因。在 SSWA 患者中，SS 内血流紊乱也是 PT 的另一个原因。SSWD 修复可能在一定程度上缓解耳鸣，但仍可能出现血流紊乱。
