Hydroacoustic analysis and extraluminal compression surgical insights of venous pulsatile tinnitus

This study aimed to quantitatively and qualitatively evaluate the hydroacoustic changes from "presence" to "disappearance" of pulsatile tinnitus (PT) with the extraluminal compression surgical technique. The recent issues of concern pertaining to the hydroacoustic characteristics of sigmoid sinus wall anomalies and distal transverse sinus stenosis (dTSS) were discussed.

This study was based on a retrospective case series. Seventy-seven patients with PT and transverse-sigmoid sinus enlargement with or without transverse-sigmoid sinus junction anomalies and transverse sinus stenosis (TSS) who had undergone extraluminal compression surgery under local anesthesia were included. Management of intractable intraoperative challenges and techniques for reversal extraluminal compression were introduced. Anatomical measurements, intraoperative color-coded Doppler ultrasonography, spectro-temporal analysis, and computational fluid dynamics were employed to analyze the hydroacoustic characteristics of PT.

The efficacy of the extraluminal compression technique was evident with the significant reduction in peak turbulent kinetic energy, vorticity, and mean pressure gradient at the transverse-sigmoid junction, resulting in over 20% reduction in PT amplitude. dTSS is a common finding in patients with PT exhibiting transverse-sigmoid sinus enlargement. Patients with dTSS presented with significant differences in hemodynamic characteristics as compared to those without. Linear regression analysis showed that the flow disturbance (turbulent kinetic energy and vorticity) was closely associated with the degree of dTSS, whereas the flow amplitude was not related to the degree or location of TSS. Low-pulsatory vortex flow at the transverse-sigmoid junction was visualized during an intraoperative color-coded Doppler examination, and the displayed low-frequency PT sound corresponded to the patients' subjective perception of PT.

(1) A reduction of over 20% of the flow-induced noise is the therapeutic goal of extraluminal compression technique. Since reductions in the magnitude of hemodynamic parameters, including turbulent kinetic energy, vorticity, and mean pressure gradient, render the flow-induced noise inaudible, besides sigmoid sinus wall anomalies, it is likely that PT develops from the aggregation of flow-based pathologies. (2) Although dTSS and diverticulum may greatly affect the hemodynamics at the transverse-sigmoid junction, in contrast to dehiscence, dTSS and diverticulum may not be the limiting factors for PT development.