Hemodynamic characteristics of sigmoid sinus wall dehiscence-pulsatile tinnitus patients with normal intracranial pressure

Introduction

Vascular pulsatile tinnitus (PT) is characterized by the abnormal perception of blood flow sounds synchronized with the heartbeat, which can result from both venous and arterial causes (1,2). Venous PT is more common, accounting for up to 84% of PT cases (1,3). Sigmoid sinus wall dehiscence (SSWD) is the most common etiology of venous PT, contributing to approximately 23–40% of PT cases (4,5). Unfortunately, the exact mechanism of SSWD-PT remains unclear, often leading to misdiagnosis and ineffective treatment.

Hemodynamic abnormalities in the sigmoid sinus are the fundamental cause of SSWD-PT (3,6,7). However, its specific characteristics have not been fully explored. To the best of our knowledge, only two studies have evaluated the hemodynamic characteristics of the sigmoid sinus in SSWD-PT patients. The first study found decreased average positive velocity, increased peak negative velocity, and a higher regurgitant fraction (RF) using two-dimensional phase-contrast cine magnetic resonance imaging (cine-MRI) (8). The second study investigated only voxel maximum velocity, maximum velocity (V_max), average velocity (V_avg), average blood flow (Flow_avg), and blood flow patterns by four-dimensional (4D)-flow MRI (9). However, other flow information (e.g., wall shear stress and through-plane velocity) should be investigated in more detail. Although some studies have assessed the hemodynamics of venous PT patients (10-14), including conditions such as SSWD, sigmoid sinus diverticulum, transverse sinus stenosis, and/or high-riding jugular bulb, the hemodynamic characteristics are likely to differ among patients with different types of venous PT. Furthermore, these studies primarily focus on blood flow features at the transverse sinus or the transverse-sigmoid sinus junction, rather than the sigmoid sinus itself, which is the site of sound generation in SSWD-PT. As a result, these studies are unable to capture the specific hemodynamic changes associated with SSWD. The blood flow field parameters of the left and right sigmoid sinuses are significantly different in normal individuals (8). However, the studies on SSWD-PT did not account for these differences and instead merged the bilateral sigmoid sinuses of normal individuals for comparison with the PT side of patients. Recent research has reported that PT symptoms disappear or are significantly reduced after lumbar puncture to decrease intracranial pressure (15), indicating that intracranial pressure is an important factor contributing to abnormal blood flow in the sigmoid sinus, which was not considered in previous studies. Therefore, the blood flow mechanisms of the sigmoid sinus should be fully explained, considering both side differences and intracranial pressure.

4D-flow MRI is an emerging imaging technology that captures the velocity field of blood flow in a three-dimensional volume throughout the cardiac cycle. It allows for detailed visualization of blood flow in the main cerebral outflow veins (16,17). Compared to other in vivo imaging techniques, it provides a more comprehensive and versatile assessment of the flow field without the need for radiation or contrast agents (10). A previous study has validated its stability and accuracy in measuring blood flow, further supporting its reliability for clinical and research applications (18).

This study aimed to assess the hemodynamic features of the sigmoid sinus in SSWD-PT patients with normal intracranial pressure using 4D-flow MRI. Based on previous studies, we hypothesize that SSWD-PT patients with normal intracranial pressure exhibit hemodynamic abnormalities in the sigmoid sinus, which may differ from the findings in studies of SSWD-PT that did not distinguish between intracranial pressure and side differences. Additionally, we explored whether these hemodynamic alterations could serve as noninvasive markers to identify SSWD as the true etiology of PT. We present this article in accordance with the STROBE reporting checklist (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-aw-2214/rc).

Methods

Subjects

The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics Committee of Beijing Tongren Hospital, Capital Medical University (No. TREC2023-KY131, approval date: 2023-11-29). All participants provided written informed consent. Between October 2019 and September 2023, 23 SSWD-PT patients with normal intracranial pressure were enrolled at Beijing Tongren Hospital, Capital Medical University, along with 35 healthy controls matched for age and sex. Patients were included based on the following criteria: (I) pulse-synchronous tinnitus that resolved upon ipsilateral internal jugular vein compression and head rotation toward the PT side; (II) SSWD identified as the sole possible etiology based on dual-phase contrast-enhanced computed tomography (DP-CECT), otoscopic examination, and physical examination; (III) normal intracranial pressure confirmed by the index of transverse sinus stenosis (ITSS) method and morphological criteria. Exclusion criteria included: (I) history of head or temporal bone surgery; (II) intracranial or ear diseases (e.g., tumors, otosclerosis); (III) comorbidities or medication use affecting intracranial pressure and blood flow (e.g., diabetes, cerebrovascular diseases, diuretics). All patients underwent DP-CECT, and all participants underwent brain magnetic resonance venography (MRV), axial T2FLAIR and T2-weighted imaging (T2WI), and 4D-flow MRI.

Imaging protocol

DP-CECT was acquired by a 256-row multi slice spiral CT (GE Healthcare, Waukesha, WI, USA) with the following parameters: 80–140 kV, 200 mA, rotation time =0.5 s, pitch =0.992, thickness =5 mm, field of view (FOV) =24×24 cm, matrix =512×512. The ascending aorta was the trigger point (area of interest 200 mm², threshold 120 HU). Contrast agent (iopamidol, 370 mgI/mL; Bracco, Shanghai, China) was intravenously administered at a dose of 1 mL/kg, 5 mL/s. Arterial images were reconstructed using standard algorithms, and the venous images were reconstructed using standard and bone algorithms.

The MRI data were acquired by a Philips Ingenia 3.0T MR unit (Philips, Best, Netherlands) with a 32-channel standard head coil. MRV parameters were as follows: velocity encoding =15 cm/s, flip angle =10°, echo time (TE) =7.1 ms, repetition time (TR) =17.9 ms, FOV =23×23 cm, matrix =232×192, acquired voxel size =1×1.2×2 mm³, reconstructed voxel size =0.9×0.9×1 mm³, acquisition time =5 min 1 s. T2FLAIR parameters were as follows: TE =110 ms, TR =9,000 ms, flip angle =90°, FOV =23×20 cm, matrix =256×187. T2WI parameters were as follows: TE =80 ms, TR =3,000 ms, flip angle =90°, FOV =12×12 cm, matrix =240×188.

4D-flow MRI was acquired by a free-breathing, peripheral pulse-gated and multishot turbo field echo sequence, with a 3-direction velocity encoding in a 4-point velocity encoding scheme. Velocity encoding was set to 120 cm/s in all directions. Each phase-encoding step resulted in a temporal resolution of 49–51 ms, which was interpolated into 14–16 cardiac phases per cycle. Parallel imaging was utilized to enhance acquisition speed, with sensitivity encoding acceleration factors of 3 and 1.5 applied in the phase-encoding direction (right to left), respectively. The parameters were as follows: TE =3.9 ms, TR =8.1 ms, flip angle =20°, FOV =16×16 cm, matrix =160×160, acquired voxel size =1×1×1.5 mm³, reconstructed voxel size =0.83×0.83×1.5 mm³, 14 heart phases, slice orientation = transverse, sampling pattern = Cartesian, number of signals acquired =1, and acquisition time =9 min 18 s.

Data analysis

DP-CECT was used to identify SSWD, defined as isolated osseous defects of the focal sigmoid plate without the formation of a diverticulum (7) (Figure 1). All images were consistently evaluated by two head and neck radiologists with 22 and 24 years of experience, respectively.

Figure 1 A left-sided PT patient with SSWD. The CT image shows a localized bone defect in the left sigmoid plate. CT, computed tomography; PT, pulsatile tinnitus; SSWD, sigmoid sinus wall dehiscence.

Intracranial pressure was evaluated using two criteria: (I) absence of clinical symptoms and MRI findings associated with idiopathic intracranial hypertension (including empty sella, optic nerve protrusion or vertical tortuosity, flattening of the posterior globe, and distension of the optic nerve sheath) (19-21); and (II) ITSS <4 on MRV (22). Stenosis in the right and left transverse sinuses was separately classified by comparing each with its immediate pre-stenosis segment: 0, normal; 1, stenosis 10–33%; 2, stenosis 33–66%; 3, stenosis >66%; and 4, hypoplasia or aplasia. Hypoplasia was defined as a transverse sinus diameter less than one-third of the superior sagittal sinus or the contralateral transverse sinus. The ITSS was calculated by multiplying the stenosis grades for each transverse sinus. An ITSS ≥4 was suspected idiopathic intracranial hypertension, whereas an ITSS <4 was considered normal (Figure 2). Two head and neck radiologists with at least 22 years of experience independently analyzed the images, with discrepancies resolved by consensus.

Figure 2 Examples of ITSS assessing intracranial pressure on MRV. (A) MRV image demonstrates degree 0 (normal) in the bilateral transverse sinuses, ITSS =0. (B) Degree 4 (hypoplasia) in the right transverse sinus and degree 0 (normal) in the left transverse sinus, ITSS =0. (C) Degree 0 (normal) in the right transverse sinus and degree 3 stenosis (arrow) in the left transverse sinus, ITSS =0. ITSS, index of transverse sinus stenosis; MRV, magnetic resonance venography.

4D-flow MRI data were processed using GTFlow software (v3.2.10, GyroTools, Zurich, Switzerland) (23). During the preprocessing phase, corrections for eddy currents and velocity aliasing were performed, followed by velocity masking and vessel segmentation. Maximum velocity points were identified through three-dimensional streamlines, and cut-planes were generated. Measurement planes were positioned perpendicular to the target vessels throughout all cardiac phases. Hemodynamic parameters were analyzed by manually drawing contours (Figure 3). V_max (cm/s) and maximum through-plane velocity (V_{tp_max}, cm/s) were determined at the time index of peak velocity occurrence by evaluating all voxels within the contour. V_avg (cm/s), average through-plane velocity (V_{tp_avg}, cm/s), Flow_avg (mL/s), forward flow volume (FFV, mL), backward flow volume (BFV, mL), RF (%), and average wall shear stress (WSS_avg, N/m²) were automatically computed over a cardiac cycle using GTFlow. The quantitative parameters were independently assessed by two radiologists with 22 and 24 years of experience, who were blinded to the clinical information of the patients. The final value for each parameter was the average of both physicians’ measurements. Streamlines were lines tangent to the local velocity vector field and were used to observe blood flow patterns. Vortex was defined by closed, concentric ring-shaped curves. Turbulent was identified by the erratic and disorganized distribution of streamlines and velocity vectors. Two experienced radiologists independently reviewed the blood flow patterns in the sigmoid sinus and subsequently reached a consensus. They were blinded to the patients’ clinical information.

Figure 3 GTFlow software processes the 4D-flow MRI data. Streamlines of PT patients (A,B). The contour represents the site of hemodynamic measurement (C). The magnitude image shows abnormal blood flow patterns in the right sigmoid sinus (D). 4D, four-dimensional; PT, pulsatile tinnitus.

Statistical analysis

Statistical analysis was conducted by SPSS (v26.0; Chicago, IL, USA) and R software (v4.5.2; R Foundation for Statistical Computing, Vienna, Austria). Normally and non-normally distributed data were expressed as mean ± standard deviation and median (interquartile range), respectively. Hemodynamics in the sigmoid sinus were compared between the sides of the controls with paired samples t-test or Wilcoxon signed-rank test. The Chi-squared test, independent samples t-test, or Mann-Whitney U test were used to assess differences in clinical data and hemodynamics between SSWD-PT patients and controls. Interobserver agreement was assessed using the interclass correlation coefficient (ICC) and ICC >0.8 was considered good repeatability. Variables with statistical differences in univariate analysis were subjected to collinearity diagnosis. Since a variance inflation factor (VIF) >5 may indicate moderate multicollinearity (24), a stricter threshold (VIF >8) was applied to exclude variables with substantial collinearity, thereby improving model stability and interpretability. The remaining variables were used to fit a multivariate logistic regression model. Receiver operating characteristic (ROC) curves were used to assess model performance and determine the best diagnostic accuracy based on the Youden index (sensitivity + specificity −1). Sensitivity, specificity, and accuracy at the threshold values, and the areas under the ROC curves (AUC) were calculated. AUCs were compared using DeLong test. Internal validation was performed using bootstrapping with 1,000 iterations to assess the model’s stability and evaluate the potential risk of overfitting (25). P<0.05 was considered statistically significant.

Results

Subject characteristics

All patients had unilateral PT, including 18 with right-side and 5 with left-side PT (ranging from 1 to 48 months). Four patients underwent sigmoid sinus wall reconstruction surgery, and the tinnitus disappeared. The demographic data of the participants are shown in Table 1. There were no significant differences in gender, age, or body mass index (BMI) between the groups (P>0.05).

Hemodynamic evaluation

Interobserver agreement was excellent for all hemodynamic parameters: area (ICC =0.93; 95% CI: 0.90–0.96), V_avg (ICC =0.94; 95% CI: 0.91–0.96), V_max (ICC =0.93; 95% CI: 0.90–0.95), V_{tp_avg} (ICC =0.92; 95% CI: 0.88–0.95), V_{tp_max} (ICC =0.92: 95% CI: 0.89–0.95), FFV (ICC =0.89; 95% CI: 0.84–0.92), BFV (ICC =0.91; 95% CI: 0.87–0.94), Flow_avg (ICC =0.88; 95% CI: 0.82–0.92), RF (ICC =0.90; 95% CI: 0.85–0.93), and WSS_avg (ICC =0.91; 95% CI: 0.87–0.94).

The hemodynamics in the bilateral sigmoid sinuses of the controls are presented in Table 2. V_avg (P=0.034), V_max (P=0.044), and FFV (P=0.049) on the right side were higher than on the left. However, no significant differences were found in area, V_{tp_avg}, V_{tp_max}, BFV, Flow_avg, RF, and WSS_avg between the sides (P>0.05). These results suggest that bilateral hemodynamics in the sigmoid sinus should not be merged for further analysis.

Table 3 shows the hemodynamics on the PT side and the corresponding side of the controls. All PT occurred on the dominant side of the transverse sinus (18 right/5 left). To maintain consistency, sigmoid sinus hemodynamics were measured on the corresponding side of the controls (27 right/8 left), and all were performed on the dominant side of the transverse sinus. There was no significant difference in the selected side between groups (P>0.99). Compared with controls, the SSWD-PT group presented higher V_avg (P<0.001), V_max (P<0.001), BFV (P<0.001), RF (P<0.001), and WSS_avg (P=0.002). However, V_{tp_avg} (P<0.001), FFV (P=0.006), and Flow_avg (P<0.001) were lower than in controls. No significant differences were found in area and V_{tp_max} between groups. Eighteen patients (78.3%) had vortex or turbulence in the symptomatic sigmoid sinus, and no abnormal blood flow patterns was found in controls (P<0.001) (Figure 3).

Diagnostic efficacy and internal validation of the model

To identify independent predictors of SSWD-PT, multivariable logistic regression was performed. Initially, eight candidate blood flow variables showing significant differences between the SSWD-PT and control groups were considered. After assessing multicollinearity, five variables with VIF >8 were excluded, leaving three variables (V_max, V_avg, and WSS_avg) for the regression analysis. Among these, V_avg and WSS_avg were identified as independent predictors (all P<0.001) and were used to construct the final combined model. The events-per-variable ratio was approximately 7.7 for the three-variable regression and 11.5 for the final two-variable model, indicating acceptable model stability. The final model regression equation is:

Logit(P)=−13.414+0.234⋅Vavg+9.512⋅WSSavg[1]

The diagnostic efficacy and ROC curves are presented in Table 4 and Figure 4. ROC analysis showed that V_avg (AUC =0.880) and WSS_avg (AUC =0.740) had predictive value. The sensitivity, specificity, and accuracy were 95.7%, 80.0%, 84.5% and 60.9%, 80.0%, 72.4%, respectively. The diagnostic efficacy of the combined model was significantly higher than that of WSS_avg (P=0.002), with an AUC, sensitivity, specificity, and accuracy of 0.934, 82.6%, 94.3%, and 87.9%, respectively. The efficacy of this diagnostic model was better than that of V_avg, although no significant difference was found (P=0.064). There was no significant difference in the diagnostic efficacy of V_avg and WSS_avg (P=0.093).

Figure 4 Hemodynamic parameters diagnostic efficacy of ROC curves. Combined_Model includes V_avg and WSS_avg. AUC, area under the curve; ROC, receiver operating characteristic; V_avg, average velocity; WSS_avg, average wall shear stress.

Internal validation using bootstrapping showed that the combined model had an AUC of 0.932 (95% CI: 0.848–0.989), with sensitivity, specificity, and accuracy of 85.2% (95% CI: 71.4–100.0%), 89.8% (95% CI: 80.8–97.3%), and 88.0% (95% CI: 79.3–96.6%), respectively. These results suggest the model’s promising stability and robustness across multiple bootstrapped samples.

Discussion

This study utilized 4D-flow MRI to assess hemodynamics and visualize blood flow patterns in the symptomatic sigmoid sinus of SSWD-PT patients with normal intracranial pressure, comparing these findings with the corresponding side in healthy controls. Increased V_avg, V_max, BFV, RF, and WSS_avg, along with decreased V_{tp_avg}, FFV, and Flow_avg were observed in SSWD-PT patients. Additionally, PT patients were more likely to exhibit vortices or turbulence in the symptomatic sigmoid sinus. These changes may provide valuable insights into the underlying mechanisms of SSWD-PT and contribute to enhancing diagnostic accuracy.

V_avg, V_max, and WSS_avg in PT patients were significantly increased, consistent with previous studies (8,10-12,26). High blood flow velocity is an important marker of venous PT (10,12). SSWD-PT patients are prone to having a smaller proximal transverse sinus area (9), which can accelerate blood flow through the narrowed region and increase the transstenotic pressure gradient (10,14). Some PT patients in our study exhibited mild unilateral or bilateral transverse sinus stenosis (ITSS <4), which may explain the increased V_avg and V_max. However, the V_avg and V_max values of the sigmoid sinus in a previous study were lower than ours (21 vs. 30.44 cm/s, and 24 vs. 63.60 cm/s, respectively) (9). This discrepancy may be due to differences in sample selection, as all patients included in our study presented normal intracranial pressure. Furthermore, high-velocity flow increases shear stress on the sigmoid sinus wall, which is consistent with our result. In addition to velocity, WSS_avg is also influenced by blood viscosity (11,27). It has been found that SSWD-PT patients exhibit increased blood viscosity due to dyslipidemia (6). Therefore, the elevated blood flow velocity and viscosity may explain the increased WSS_avg. The repeated and forceful blood flow impingement on the sigmoid plate gradually leads to its thinning and dehiscence. Once the sigmoid plate is defective, vibrations of the sigmoid sinus wall may be transmitted to the mastoid air cells through the defect areas and finally be received by the inner ear (28). This theory is supported by a study demonstrating that simulated venous sounds were inaudible in cases with an intact sigmoid plate (29).

BFV and RF were significantly increased, while V_{tp_avg}, FFV, and Flow_avg were significantly decreased in the PT group. These changes may be related to increased blood flow resistance and abnormal blood flow patterns. SSWD-PT patients have been reported to commonly present with dyslipidemia (6), which could lead to increased blood density and viscosity, as well as elevated resistance to blood return from the venous sinus to the heart (8). In turn, it leads to an increase in BFV and RF, consistent with our findings. Furthermore, increased reverse flow enhances blood flow complexity and may promote the formation of vortices or turbulence (8). In our study, SSWD-PT patients were prone to exhibit vortices or turbulence, which aligns with a previous study (10). V_{tp_avg} is influenced by the stability and directionality of blood flow. Increased vortex, turbulence, and reverse flow weaken the stability and directionality of blood flow, leading to a decrease in V_{tp_avg}. In addition, these factors also contribute to a reduction in forward blood flow through the sigmoid sinus, which may explain the observed decrease in FFV and Flow_avg.

Accurate etiologic diagnosis is crucial for guiding subsequent treatment decisions. Currently, morphological abnormalities identified on CT are used as the diagnostic criterion for SSWD-PT (21). However, some studies have reported that SSWD also occurs in 5% (3/60) of patients without PT symptoms and 15.9% (80/504) of normal individuals (7,30), suggesting that morphology-based diagnostic criteria are insufficient. Blood flow abnormalities in the sigmoid sinus are essential for PT sound generation. The combination of V_avg and WSS_avg has the highest diagnostic efficacy, with an accuracy of 87.9%. Internal validation using bootstrapping (1,000 iterations) suggested that the model shows promising stability and robustness, with an AUC of 0.932. Compared to the morphology method, the hemodynamic diagnostic approach may help improve the accuracy of identifying SSWD as the true cause of PT. Additionally, intracranial pressure was indirectly assessed using ITSS and morphological markers, which means that a few patients with slightly elevated true intracranial pressure could have been misclassified as normal and included in the study. Such potential misclassification could subtly affect the observed hemodynamic differences, increasing within-group variability and slightly influencing the statistical significance of between-group differences. This may also have a minor impact on the diagnostic model, occasionally producing false negatives or false positives, and slightly reducing sensitivity, specificity, and AUC. Future studies incorporating lumbar puncture are needed to further validate the accuracy and reliability of hemodynamic diagnostic model.

While 4D-flow MRI demonstrates promising diagnostic performance for SSWD-PT by providing detailed hemodynamic information, its integration into routine clinical workflows requires consideration of practical factors. 4D-flow MRI is more costly and less widely available than CT, and it requires specialized equipment and trained personnel. Nevertheless, it provides complementary information beyond CT-based morphology, such as the assessment of flow velocity, volume, and WSS_avg, which may improve diagnostic accuracy when CT findings are inconclusive. Therefore, 4D-flow MRI could be considered an adjunctive tool for selected patients, particularly when clinical suspicion is high or CT-based evaluation is insufficient. Furthermore, hemodynamic assessment offers clinicians an objective, quantifiable tool that may be valuable for guiding treatment decisions and predicting treatment outcomes.

This study has some limitations. First, the evaluation of intracranial pressure relied solely on indirect imaging indices, which may introduce potential misclassification bias. Although lumbar puncture is considered the gold standard for assessing intracranial pressure, it is invasive and may raise ethical concerns and complications. The ITSS method has shown high sensitivity and specificity in evaluating intracranial pressure (94.7% and 93.5%, respectively) (22). While the combination of ITSS and morphological methods provides a double guarantee for evaluating intracranial pressure, further validation with lumbar puncture confirmation could enhance diagnostic accuracy. Second, we only investigated the hemodynamics in PT patients and did not explore whether there were sex-related hemodynamic differences, given the high prevalence of women among PT patients (5,6). Third, this is a single-center study with a relatively small sample size, which may limit the generalizability of the findings. However, to improve the stability of the model, we performed collinearity diagnostics on the significant variables identified from univariate analysis and excluded those with a VIF greater than 8. Additionally, we performed internal validation using bootstrapping to reduce the risk of overfitting. Future research with larger, multi-center cohorts is needed to further validate our findings and assess their applicability in a broader population.

Conclusions

SSWD-PT patients with normal intracranial pressure exhibit hemodynamic changes in the symptomatic sigmoid sinus, including the presence of vortex or turbulence, along with significantly increased V_avg, V_max, BFV, RF, and WSS_avg, and decreased V_{tp_avg}, FFV, and Flow_avg. The combination of V_avg and WSS_avg may serve as a noninvasive indicator to improve the accuracy of identifying the true etiology of SSWD-PT.

Acknowledgments

None.

Footnote

Reporting Checklist: The authors have completed the STROBE reporting checklist. Available at https://qims.amegroups.com/article/view/10.21037/qims-2025-aw-2214/rc

Data Sharing Statement: Available at https://qims.amegroups.com/article/view/10.21037/qims-2025-aw-2214/dss

Funding: This work was supported by the National Natural Science Foundation of China (No. 82071882) and Natural Science Foundation of Beijing Municipal (No. 7222029).

Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://qims.amegroups.com/article/view/10.21037/qims-2025-aw-2214/coif). All authors declared that this work was supported by the National Natural Science Foundation of China (No. 82071882) and Natural Science Foundation of Beijing Municipal (No. 7222029). The authors have no other conflicts of interest to declare.

Ethical Statement: The authors are accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved. The study was conducted in accordance with the Declaration of Helsinki and its subsequent amendments. The study was approved by the Ethics Committee of Beijing Tongren Hospital, Capital Medical University (No. TREC2023-KY131, approval date: 2023-11-29). All participants provided written informed consent.

Open Access Statement: This is an Open Access article distributed in accordance with the Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International License (CC BY-NC-ND 4.0), which permits the non-commercial replication and distribution of the article with the strict proviso that no changes or edits are made and the original work is properly cited (including links to both the formal publication through the relevant DOI and the license). See: https://creativecommons.org/licenses/by-nc-nd/4.0/.

References

1. Dong C, Zhao PF, Yang JG, Liu ZH, Wang ZC. Incidence of vascular anomalies and variants associated with unilateral venous pulsatile tinnitus in 242 patients based on dual-phase contrast-enhanced computed tomography. Chin Med J (Engl) 2015;128:581-5. [Crossref] [PubMed]
2. Lockwood AH, Salvi RJ, Burkard RF. Tinnitus. N Engl J Med 2002;347:904-10. [Crossref] [PubMed]
3. Lyu AR, Park SJ, Kim D, Lee HY, Park YH. Radiologic features of vascular pulsatile tinnitus - suggestion of optimal diagnostic image workup modalities. Acta Otolaryngol 2018;138:128-34. [Crossref] [PubMed]
4. Mundada P, Singh A, Lingam RK. CT arteriography and venography in the evaluation of Pulsatile tinnitus with normal otoscopic examination. Laryngoscope 2015;125:979-84. [Crossref] [PubMed]
5. Schoeff S, Nicholas B, Mukherjee S, Kesser BW. Imaging prevalence of sigmoid sinus dehiscence among patients with and without pulsatile tinnitus. Otolaryngol Head Neck Surg 2014;150:841-6. [Crossref] [PubMed]
6. Wang GP, Zeng R, Liu ZH, Liang XH, Xian JF, Wang ZC, Gong SS. Clinical characteristics of pulsatile tinnitus caused by sigmoid sinus diverticulum and wall dehiscence: a study of 54 patients. Acta Otolaryngol 2014;134:7-13. [Crossref] [PubMed]
7. Zhao P, Lv H, Dong C, Niu Y, Xian J, Wang Z. CT evaluation of sigmoid plate dehiscence causing pulsatile tinnitus. Eur Radiol 2016;26:9-14. [Crossref] [PubMed]
8. Liu Z, He X, Du R, Wang G, Gong S, Wang Z. Hemodynamic Changes in the Sigmoid Sinus of Patients With Pulsatile Tinnitus Induced by Sigmoid Sinus Wall Anomalies. Otol Neurotol 2020;41:e163-7. [Crossref] [PubMed]
9. Dai C, Zhao P, Wang G, Ding H, Lv H, Qiu X, Tang R, Xu N, Huang Y, He K, Yang Z, Gong S, Wang Z. Hemodynamic assessments of unilateral pulsatile tinnitus with jugular bulb wall dehiscence using 4D flow magnetic resonance imaging. Quant Imaging Med Surg 2024;14:684-97. [Crossref] [PubMed]
10. Li Y, Chen H, He L, Cao X, Wang X, Chen S, Li R, Yuan C. Hemodynamic assessments of venous pulsatile tinnitus using 4D-flow MRI. Neurology 2018;91:e586-93. [Crossref] [PubMed]
11. Mu Z, Li X, Zhao D, Qiu X, Dai C, Meng X, Huang S, Gao B, Lv H, Li S, Zhao P, Liu Y, Wang Z, Chang Y. Hemodynamics study on the relationship between the sigmoid sinus wall dehiscence and the blood flow pattern of the transverse sinus and sigmoid sinus junction. J Biomech 2022;135:111022. [Crossref] [PubMed]
12. Li X, Qiu X, Ding H, Lv H, Zhao P, Yang Z, Gong S, Wang Z. Effects of different morphologic abnormalities on hemodynamics in patients with venous pulsatile tinnitus: A four-dimensional flow magnetic resonance imaging study. J Magn Reson Imaging 2021;53:1744-51. [Crossref] [PubMed]
13. Li Z, Jin L. Study on the correlation between hemodynamic status of the transverse sinus-sigmoid sinus and the clinical efficacy of sigmoid sinus wall reconstruction. Interv Neuroradiol 2022;28:687-94. [Crossref] [PubMed]
14. Han Y, Xia J, Jin L, Qiao A, Su T, Li Z, Xiong J, Wang H, Zhang Z. Computational fluid dynamics study of the effect of transverse sinus stenosis on the blood flow pattern in the ipsilateral superior curve of the sigmoid sinus. Eur Radiol 2021;31:6286-94. [Crossref] [PubMed]
15. Haraldsson H, Leach JR, Kao EI, Wright AG, Ammanuel SG, Khangura RS, Ballweber MK, Chin CT, Shah VN, Meisel K, Saloner DA, Amans MR. Reduced Jet Velocity in Venous Flow after CSF Drainage: Assessing Hemodynamic Causes of Pulsatile Tinnitus. AJNR Am J Neuroradiol 2019;40:849-54. [Crossref] [PubMed]
16. Kao E, Kefayati S, Amans MR, Faraji F, Ballweber M, Halbach V, Saloner D. Flow patterns in the jugular veins of pulsatile tinnitus patients. J Biomech 2017;52:61-7. [Crossref] [PubMed]
17. Kefayati S, Amans M, Faraji F, Ballweber M, Kao E, Ahn S, Meisel K, Halbach V, Saloner D. The manifestation of vortical and secondary flow in the cerebral venous outflow tract: An in vivo MR velocimetry study. J Biomech 2017;50:180-7. [Crossref] [PubMed]
18. Dyverfeldt P, Bissell M, Barker AJ, Bolger AF, Carlhäll CJ, Ebbers T, Francios CJ, Frydrychowicz A, Geiger J, Giese D, Hope MD, Kilner PJ, Kozerke S, Myerson S, Neubauer S, Wieben O, Markl M. 4D flow cardiovascular magnetic resonance consensus statement. J Cardiovasc Magn Reson 2015;17:72. [Crossref] [PubMed]
19. Liu Z, Dong C, Wang X, Han X, Zhao P, Lv H, Li Q, Wang Z. Association between idiopathic intracranial hypertension and sigmoid sinus dehiscence/diverticulum with pulsatile tinnitus: a retrospective imaging study. Neuroradiology 2015;57:747-53. [Crossref] [PubMed]
20. Xu S, Ruan S, Liu S, Xu J, Gong R. CTA/V detection of bilateral sigmoid sinus dehiscence and suspected idiopathic intracranial hypertension in unilateral pulsatile tinnitus. Neuroradiology 2018;60:365-72. [Crossref] [PubMed]
21. Eisenman DJ, Raghavan P, Hertzano R, Morales R. Evaluation and treatment of pulsatile tinnitus associated with sigmoid sinus wall anomalies. Laryngoscope 2018;128:S1-S13. [Crossref] [PubMed]
22. Carvalho GB, Matas SL, Idagawa MH, Tibana LA, de Carvalho RS, Silva ML, Cogo-Moreira H, Jackowski AP, Abdala N. A new index for the assessment of transverse sinus stenosis for diagnosing idiopathic intracranial hypertension. J Neurointerv Surg 2017;9:173-7. [Crossref] [PubMed]
23. Nordmeyer S, Riesenkampff E, Crelier G, Khasheei A, Schnackenburg B, Berger F, Kuehne T. Flow-sensitive four-dimensional cine magnetic resonance imaging for offline blood flow quantification in multiple vessels: a validation study. J Magn Reson Imaging 2010;32:677-83. [Crossref] [PubMed]
24. Tomaschek F, Hendrix P, Baayen RH. Strategies for addressing collinearity in multivariate linguistic data. Journal of Phonetics 2018;71:249-267. [Crossref]
25. Steyerberg EW, Harrell FE Jr, Borsboom GJ, Eijkemans MJ, Vergouwe Y, Habbema JD. Internal validation of predictive models: efficiency of some procedures for logistic regression analysis. J Clin Epidemiol 2001;54:774-81. [Crossref] [PubMed]
26. Lv K, Zheng S, Wang H, Zhao C, Yu Z, Shen Z, Xu K, Chai C, Xia S. Interactive effect of hemodynamics in transverse sigmoid sinus and bone morphology on venous pulsatile tinnitus: a four-dimensional (4D) flow magnetic resonance imaging (MRI) study. Quant Imaging Med Surg 2024;14:6647-59. [Crossref] [PubMed]
27. Reneman RS, Arts T, Hoeks AP. Wall shear stress--an important determinant of endothelial cell function and structure--in the arterial system in vivo. Discrepancies with theory. J Vasc Res 2006;43:251-69. [Crossref] [PubMed]
28. Liu Z, Chen C, Wang Z, Gong S, Xian J, Wang Y, Liang X, Ma X, Li Y. Sigmoid sinus diverticulum and pulsatile tinnitus: analysis of CT scans from 15 cases. Acta Radiol 2013;54:812-6. [Crossref] [PubMed]
29. Tian S, Fan X, Wang Y, Liu Z, Wang L. An in vitro experimental study on the relationship between pulsatile tinnitus and the dehiscence/thinness of sigmoid sinus cortical plate. J Biomech 2019;84:197-203. [Crossref] [PubMed]
30. Liu Z, Li J, Zhao P, Lv H, Dong C, Liu W, Wang Z. Sigmoid plate dehiscence: congenital or acquired condition? Eur J Radiol 2015;84:862-4. [Crossref] [PubMed]