Sound Measurement in Patient-Specific 3D Printed Bench Models of Venous Pulsatile Tinnitus

Abstract

Hypothesis:We hypothesize patient-specific flow models to be an adequate in vitro surrogate to allow for characterization of Pulsatile Tinnitus that affects 3-5 million Americans.Background: Pulsatile tinnitus (PT), rhythmic sounds without an extracorporeal source that patients appreciate, can be caused by aberrant blood flow in large cerebral veins near the cochlea. In order to investigate the sound production mechanism, we created 3D printed flow models based on patient-specific cerebral venous anatomies.Methods: Magnetic resonance angiography datasets from two patients with PT were used to generate patient-specific 3D printed flow models. A flow circuit connecting the patient-specific models to a pulsatile, continuous flow pump simulating cardiac cycle was created. Sound recordings were made along the surface of the models using an electronic stethoscope. Peak-torms amplitude, and area under the power spectral density (PSD) curve values were computed to evaluate the sound measurements. Wilcoxon rank sum test was used to statistically determine the differences in measurements between the patient-specific models. Results:In patient-1, the recordings (peak-to-rms) from the internal jugular vein stenosis of baseline model (4.29±1.26 for 146 samples) were significantly louder (p<0.001) than that of the altered model (3.29±0.96 for 143 samples). In patient-2, the sound measured at the transverse sinus stenosis in the pre-lumbar puncture model (4.84±1.11 for 148 samples) was significantly louder (p<0.0001) than that of the post-lumbar puncture model (3.14±0.87 for 135 samples). Conclusions:The models are able to generate sounds very similar to those appreciated by patients and examiners in the cases of objective PT.

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

“…The blood flow sound of venous PT was previously studied using 3D-printed models via different recording methods. (13,15) In congruence with a recent in vitro study conducted by Valluru et al that found that the main power of PT fell below 600 Hz using an electrical stethoscope, (15) both our in vivo ultrasonography and in vitro experiments showed similar results regarding frequency components. However, since the properties of the materials used for 3D-printed models vary significantly among the studies, to avoid sound impedance and sound transmission loss caused by the applied materials, an intravascularly placed hydrophone allows the analysis of the magnitude of the flow amplitude generated inside the sigmoid sinus.…”

Management of vascular causes of pulsatile tinnitus

“…Development of patient-specific three-dimensional-printed flow models that mimic a patient's hemodynamic conditions also allows physicians to better narrow down the specific causes of a patient's PT, and simulate treatment before the intervention. 47 In the future, phase-contrast MRI (ie, four-dimensional flow), fluid dynamic modeling with sound simulation, and intravascular sound recordings will likely play a larger role in disease assessment, particularly as part of clinical trials. Arterial causes of PT, such as carotid stenosis and dAVF, can bear a risk of stroke in addition to causing PT, and therefore may warrant treatment for multiple reasons.…”

“…We have provided our UCSF Cerebral Venous Disorder Testing form as online supplemental material, which guides our assessment of venous causes of PT currently. Development of patient-specific three-dimensional-printed flow models that mimic a patient’s hemodynamic conditions also allows physicians to better narrow down the specific causes of a patient’s PT, and simulate treatment before the intervention 47. In the future, phase-contrast MRI (ie, four-dimensional flow), fluid dynamic modeling with sound simulation, and intravascular sound recordings will likely play a larger role in disease assessment, particularly as part of clinical trials.…”

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

“…Extrinsic sensing applications to assess the sound transmission of PT inside the mastoid bone have recently been attempted on both in vivo and in vitro 3D-printing platforms ( Tian et al, 2019 ; Valluru et al, 2020 ; Hsieh and Wang, 2021 ). As the sound wave pressure dampens due to surrounding human anatomical structures, the acquisition of the absolute amplitude of PT in vivo can be rather arduous.…”