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

The application of grafts and biomaterials is a cardinal therapeutic procedure to resolve venous pulsatile tinnitus (PT) caused by temporal bone dehiscence during transtemporal reconstructive surgery. However, the transmission mechanism of venous PT remains unclear, and the sound absorption and insulation properties of different repair materials have not been specified. This study quantifies the vibroacoustic characteristics of PT, sources the major transmission pathway of PT, and verifies the therapeutic effect of different material applications using joint multi-sensing platforms and coupled computational fluid dynamics (CFD) techniques. The in vivo intraoperative acoustic and vibroacoustic characteristics of intrasinus blood flow motion and dehiscent sigmoid plate of a typical venous PT patient were investigated using acoustic and displacement sensors. The acoustical, morphological, and mechanical properties of the dehiscent sigmoid plate, grafts harvested from a cadaveric head, and other biomaterials were acquired using acoustical impedance tubes, micro-CT, scanning electron microscopy, and mercury porosimetry, as appropriate. To analyze the therapeutic effect of our previous reconstructive techniques, coupled CFD simulations were performed using the acquired mechanical properties of biomaterials and patient-specific radiologic data. The peak in vivo intraoperatively gauged, peak simulated vibroacoustic and peak simulated hydroacoustic amplitude of PT prior to sigmoid plate reconstruction were 64.0, 70.4, and 72.8 dB, respectively. After the solidified gelatin sponge–bone wax repair technique, the intraoperative gauged peak amplitude of PT was reduced from 64.0 to 47.3 dB. Among three different reconstructive techniques based on CFD results, the vibroacoustic and hydroacoustic sounds were reduced to 65.9 and 68.6 dB (temporalis–cartilage technique), 63.5 and 63.1 dB (solidified gelatin sponge technique), and 42.4 and 39.2 dB (solidified gelatin sponge–bone wax technique). In conclusion, the current novel biosensing applications and coupled CFD techniques indicate that the sensation of PT correlates with the motion and impact from venous flow, causing vibroacoustic and hydroacoustic sources that transmit via the air-conduction transmission pathway. The transtemporal reconstructive surgical efficacy depends on the established areal density of applied grafts and/or biomaterials, in which the total transmission loss of PT should surpass the amplitude of the measured loudness of PT.

Transverse Sinus Stenosis in Venous Pulsatile Tinnitus Patients May Lead to Brain Perfusion and White Matter Changes

Objective: Transverse sinus stenosis (TSS) is associated with various symptoms, but whether it can lead to pathological brain changes is unclear. This study aimed to investigate brain changes in venous pulsatile tinnitus (PT) patients with TSS.Materials and Methods: In this study, fifty-five consecutive venous PT patients and fifty age- and gender-matched healthy controls (HCs) were investigated. In CT venography, the combined conduit score (CCS) was used to assess the degree of TSS in venous PT patients. Magnetic resonance venography was used to assess TSS in HCs. All the participants had undergone arterial spin labeling and structural MRI scans.Results: Two patients without TSS and ten HCs with TSS were excluded. Fifty-three venous PT patients with TSS and 40 HCs without TSS were included in this study. All the patients had unilateral cases: 16 on the left and 37 on the right. Based on the CCS, the patients were divided into high-degree TSS (a score of 1–2) (n = 30) and low-degree TSS groups (a score of 3–4) (n = 23). In the whole brain and gray matter, the patients with high-degree TSS showed decreased cerebral blood flow (CBF) compared with patients with low-degree TSS as well as HCs (P < 0.05), and no significant difference in CBF was found in patients with low-degree TSS and HCs (P > 0.05). In white matter (WM) regions, the patients with high-degree TSS exhibited decreased CBF relative to the HCs (P < 0.05). The incidence of cloud-like WM hyperintensity was significantly higher in the above two patient groups than in the HC group (P < 0.05).Conclusion: TSS in venous PT patients may lead to decreased CBF and cloud-like WM hyperintensity. These neuroimaging findings may provide new insights into pathological TSS in venous PT.

Study on the correlation between hemodynamic status of the transverse sinus-sigmoid sinus and the clinical efficacy of sigmoid sinus wall reconstruction

Background and Purpose For patients with pulsatile tinnitus who have both transverse sinus stenosis and sigmoid sinus wall anomalies, sigmoid sinus wall reconstruction surgery is the first-choice treatment when the trans-stenotic pressure gradient less than 10 mmHg. However, not all patients are cured by surgery. We hypothesized the abnormal hemodynamics caused by transverse sinus stenosis is associated with the clinical efficacy of surgery. Methods Eight pulsatile tinnitus patients treated with surgery were retrospectively reviewed (4 rehabilitated, 4 nonrehabilitated). All patients had radiologically diagnosed transverse sinus stenosis and sigmoid sinus wall anomalies. A numerical simulation of the hemodynamics of the transverse sinus-sigmoid sinus was performed using computational fluid dynamics technology. Changes in the blood flow patterns before and after surgery were observed. The blood flow velocity at the stenosis, vorticity of blood flow in the sigmoid sinus and wall pressure distribution in the sigmoid sinus wall anomalies area were compared. Results The blood flow velocity in the stenosis (preoperative P = 0.04, postoperative P = 0.004) and vorticity in the sigmoid sinus (preoperative P = 0.02, postoperative P = 0.007) pre- and post-surgery were significantly higher in the non-rehabilitation group than in the rehabilitation group. No significant difference was found in the wall pressure distribution in the sigmoid sinus wall anomalies area (preoperative P = 0.12, postoperative P = 0.24). Conclusions There is a clear correlation between the abnormal hemodynamic status caused by transverse sinus stenosis and the clinical efficacy of surgery. The blood flow velocity at the stenosis and vorticity of blood flow in the sigmoid sinus are factors influencing the clinical efficacy of surgery.