Hydroacoustic Sonification and Flow Pattern Investigation of Venous Pulsatile Tinnitus Using MEMS Hydrophone Sensing and Dye Flow Visualization Techniques: Pilot 3D Printing, Computational Fluid Dynamics, and Psychoacoustic Study

Venous pulsatile tinnitus (PT) has been increasingly recognized in otology and neurotologic clinics. Although venous PT is surgically treatable, the surgical efficacy has unfortunately remained inconsistent owing to the relatively unknown mechanistic and psychophysical aspects of venous PT. We investigated the connection between the hydroacoustic and psychophysical characteristics of venous PT by integrating the outcomes attained from in vivo Doppler ultrasound, in vitro experiments, and psychoacoustic examination. The dye flow visualization technique used to investigate flow patterns was first introduced to this specific research topic. All 3D-printed and finite-element models were reconstructed on the basis of patients' magnetic resonance images. A MEMS hydrophone sensor was placed in the jugular bulb region intraluminally to study the operative alteration of the fluid-borne sound. Computational fluid dynamics (CFD) techniques were also implemented to cross-reference with the results of in vitro experiments. The in vitro and computational experimental outcomes showed that venous PT is the perception of intrasinus blood flow motion, in which the fluid flow amplitude may be associated with the ipsilateral flow volume and pressure gradient. In addition, the dye flow technique is beneficial for the study of intravascular flow patterns. However, in vitro/computational study results may potentially deviate from in vivo clinical measurements when the materials and parameters used for experiments are varied. Thus, modifications and refinements of the applied sensing and materials are warranted in further experimental studies.