Time-frequency analysis of venous pulsatile flow and sigmoid sinus vascular wall displacement causing pulsatile tinnitus using time series and magnitude squared coherence methods

Displacement of the sigmoid sinus vascular wall and intrasinus blood flow motion is known to cause pulsatile tinnitus (PT) in patients with sigmoid plate dehiscence. To investigate the source of sound that causes PT, this study sought to determine the correlation between in vivo displacement of the vascular wall and intrasinus flow hemodynamics. A confocal laser displacement sensor and color-coded Doppler ultrasound system were implemented on a participant diagnosed with venous PT. The displacement and Doppler velocity data were analyzed using time series and magnitude squared coherence methods. The median and peak displacement values of the vascular wall were 6.7 μm and 11.7 μm, respectively. The major frequency range of vascular displacement was below 4 Hz. The portmanteau test was rejected for different values of m. The cross-correlation of the two processes was not zero, indicating the existence of cross-correlation. The peak magnitude squared coherence of the two gauged signals was 0.3 at 7.143 Hz. The displacement of the sigmoid sinus vascular wall was temporally correlated with the intrasinus flow, although the major frequency range of the induced vascular displacement fell below the human hearing threshold. Therefore, the hydroacoustic and vibroacoustic sounds induced by the fluid-structure interaction between the vascular and osseous structures overweighed the displacement of the vascular wall at the focal dehiscence area in PT production.