Dynamic Properties of Tympanic Membrane in a Chinchilla Otitis Media Model Measured With Acoustic Loading

Abstract

Otitis media is the most common infectious disease in young children, which results in changes in the thickness and mechanical properties of the tympanic membrane (TM) and induces hearing loss. However, there are no published data for the dynamic properties of the TM in otitis media ears, and it is unclear how the mechanical property changes are related to TM thickness variation. This paper reports a study of the measurement of the dynamic properties of the TM in a chinchilla acute otitis media (AOM) model using acoustic loading and laser Doppler vibrometry (LDV). AOM was created through transbullar injection of Haemophilus influenzae into the middle ear, and AOM samples were prepared 4 days after inoculation. Vibration of the TM specimen induced by acoustic loading was measured via LDV over a frequency range of 0.1-8 kHz. The experiment was then simulated in a finite element (FE) model, and the inverse-problem solving method was used to determine the complex modulus in the frequency domain. Results from 12 ears (six control and six AOM) show that the storage modulus of the TM from AOM ears was on average 53% higher than that of control ears, while the loss factor was 17.3% higher in control ears than in AOM ears at low-frequency (f < 1 kHz). At high-frequency (e.g., 8000 Hz), there was a mean 40% increase in storage modulus of the TM from AOM compared to control samples. At peak frequency (e.g., 3 kHz), there was a 19.5% increase in loss factor in control samples compared to AOM samples. These findings quantify the changes induced by AOM in the chinchilla TM, namely, a significant increase in both the storage and loss moduli.

3D finite element model of the chinchilla ear for characterizing middle ear functions

“…Fay estimated the Young’s modulus of fiber layer ranged 100–220 MPa posterior and 200–400 MPa anterior for the cat TM. Recently, our experimental results showed that the Young’s modulus of the chinchilla pars tensa was about 6–10 times higher than that of the human pars tensa (Yokell et al, 2015). The Young’s modulus of the TM was determined by the cross-calibration of the TM and FP displacements (Sun et al 2002), and a modulus value of 200 MPa was achieved for the pars tensa of TM in this study.…”

Morphological changes in the round window membrane associated with Haemophilus influenzae-induced acute otitis media in the chinchilla

“…The chinchilla model of AOM produced by transbullar injection of H. influenzae strain 86-028NP has been widely used for various research purposes [12, 13, 26–30]. Recently we used this AOM model to identify biomechanical changes in hearing associated with the effects of acute infection on the tympanic membrane [13, 30].…”

“…Recently we used this AOM model to identify biomechanical changes in hearing associated with the effects of acute infection on the tympanic membrane [13, 30]. In the present study, we utilized this model to assess the early acute impact (days 4 and 8 post bacterial challenge) of this H. influenzae strain on RWM histopathological changes.…”

Dynamic property changes in stapedial annular ligament associated with acute otitis media in the chinchilla

“…To measure variation of any mechanical properties in AOM ears, an animal model is necessary for experimental approach because AOM cannot be induced properly in cadaver temporal bones. Recently, an AOM model was created in the chinchilla and the changes in mechanical properties of TM and RWM were reported by Yokell et al [13] and Wang et al [14]. For the SAL, however, biomechanical changes in pathological ears have never been reported.…”

“…It is also unknown how the mechanical properties of the SAL vary as the AOM infection progresses. The degree of inflammatory response changes during AOM development, but how this affects the mechanical properties of SAL across the infection period remains unclear [13, 14]. Therefore, further investigation of SAL in AOM ears is needed to understand the mechanism of AOM-induced hearing loss.…”