STUDY ON VIBRATION CHARACTERISTICS AND TRANSMISSION PERFORMANCE OF ROUND WINDOW MEMBRANE UNDER INVERSE EXCITATION

2018 ◽  
Vol 18 (03) ◽  
pp. 1850033 ◽  
Author(s):  
WENJUAN YAO ◽  
DUTIN TANG ◽  
YIQIANG CHEN ◽  
BINGTAI LI
Keyword(s):  
Elastic Modulus ◽  
Soft Tissue ◽  
Analytical Solution ◽  
Round Window ◽  
Vibration Characteristics ◽  
Round Window Membrane ◽  
Transmission Performance ◽  
Total Displacement ◽  
The Relationship ◽  
Artificial Prosthesis

According to the vibration characteristics of the round window membrane, a mechanical model that contains round window membrane and the soft tissue is established. The Euler equation of the whole of round window membrane and the soft tissue and the complementary boundary conditions are derived by the variational principle. Combined with the Bessel function, the analytical solution of the total displacement of round window membrane and the soft tissue is obtained by using Mathematica. The results are in good agreement with experimental data, which confirms the validity of the analytical solution of the model. At the same time, the effect of different thicknesses and different elastic modulus of soft tissue on the total displacement of round window membrane and soft tissue is studied by analytical method. The results show that with the thickening of the soft tissue, the total displacement of round window membrane and the soft tissue decreased gradually. However, with the decrease of elastic modulus of the soft tissue, the total displacement of round window membrane and the soft tissue increased gradually. Furthermore, the relationship between thickness and elastic modulus of the soft tissue and the corresponding range selection is achieved, which can evaluate the transmission performance of round window membrane efficiently and provide theoretical basis for the reverse excitation of artificial prosthesis.

Study on a New Testing Method of the Elastic Modulus and Poisson's Ratio by Using Brazilian Disk Test

2013 ◽  
Vol 347-350 ◽  
pp. 1199-1202
Author(s):  
Fei Wu ◽  
Shi Ming Dong
Keyword(s):  
Elastic Modulus ◽  
Poisson’S Ratio ◽  
Vertical Direction ◽  
Test Method ◽  
Poisson's Ratio ◽  
Theoretical Formula ◽  
Brazilian Disk ◽  
Total Displacement ◽  
The Relationship ◽  
Poissons Ratio

In order to develop a new test method of the elastic modulus and Poissons ratio, based on the theoretical analysis of the Brazilian disk diametrically loaded by a pair of forces, the relationship is obtained between the total displacement of one point on the vertical direction of the load line and the applied force as well as the elastic modulus and Poissons ratio. The strain gauges with different length are used to measure the displacement of the corresponding point, and then the displacement is employed to calculate the elastic modulus and Poisson's ratio by using the theoretical formula. The proposed method can provide a new approach to estimate the elastic modulus and Poissons ratio by using Brazilian disk splitting tests.

scholarly journals Pneumolabyrinth: Radiologic Evidence of Labyrinthine Injury

2008 ◽  
Vol 23 (2) ◽  
pp. 49-50
Author(s):  
Nathaniel W. Yang
Keyword(s):  
Soft Tissue ◽  
Inner Ear ◽  
Tympanic Membrane ◽  
Temporal Bone ◽  
Bone Fractures ◽  
Round Window ◽  
Spontaneous Nystagmus ◽  
Head Impulse Test ◽  
Round Window Membrane ◽  
The Right

A U.S. serviceman presented with a three month history of unsteadiness on ambulation and increasing episodes of vertigo whenever he turned his head rapidly to the right. He had previously been injured in a bomb blast while stationed in Iraq four months prior to consultation. Aside from multiple soft tissue and bone trauma, he had also experienced vertigo and nearly complete deafness in the right ear immediately after the blast. Medical records indicated the presence of a traumatic perforation of the right tympanic membrane and spontaneous nystagmus on initial emergency medical assessment after the incident. Physical examination on consultation revealed bilaterally intact eardrums, a positive right head impulse test, and a normal Romberg test. Audiometry showed a severe right SNHL. A presumptive diagnosis of a persistent perilymph fistula secondary to inner ear barotrauma was entertained, and supported by findings on temporal bone CT imaging. Figure 1 is the axial CT image of the patient's inner ear at the level of the basal turn of the cochlea. Two linear lucencies are visible within the cochlea (arrowheads). These have the same signal characteristics as the normal external auditory canal and middle ear space. As such, they indicate the presence of air within the cochlea – a condition termed pneumolabyrinth. Figure 2 shows a normal cochlea at the same level for comparison. Note the uniform soft tissue density within the cochlear lumen, representing the endocochlear fluids. The lucency in the round window niche (thin arrow) also represents air, but this is a normal finding.   Barotrauma from blast injuries and traumatic tympanic membrane perforations may cause perilymph fistulas. This is probably due to a sudden pressure wave transmitted through the tympanic membrane that results in an inward rupture of the round window membrane or an inward displacement of the stapedial footplate.1 Pneumolabyrinth has been identified in patients suffering from perilymph fistulas due to barotraumas,2 and therefore can bolster the diagnosis when identified in the appropriate clinical setting. It has also been identified in patients with perilymph fistulas from other causes, including iatrogenic stapes fractures during mastoid surgery, temporal bone fractures, cholesteatoma, neoplasms of the temporal bone, stapedectomy, and after cochlear implantation.3

scholarly journals Round Window Reinforcement-Induced Changes in Intracochlear Sound Pressure

2021 ◽  
Vol 11 (11) ◽  
pp. 5062
Author(s):  
Nuwan Liyanage ◽  
Lukas Prochazka ◽  
Julian Grosse ◽  
Adrian Dalbert ◽  
Sonia Tabibi ◽  
...  
Keyword(s):  
Soft Tissue ◽  
Sound Pressure ◽  
Numerical Models ◽  
Round Window ◽  
Acoustic Stimulation ◽  
Pressure Increase ◽  
Round Window Membrane ◽  
Superior Semicircular Canal Dehiscence ◽  
Experimental Findings ◽  
Temporal Bones

Introduction: The round window membrane (RWM) acts as a pressure-relieving membrane for incompressible cochlear fluid. The reinforcement of the RWM has been used as a surgical intervention for the treatment of superior semicircular canal dehiscence and hyperacusis. The aim of this study was to investigate how RWM reinforcement affects sound pressure variations in the cochlea. Methods: The intracochlear sound pressure (ICSP) was simultaneously measured in the scala tympani (ST) and scala vestibuli (SV) of cadaveric human temporal bones (HTBs) in response to acoustic stimulation for three RWM reinforcement materials (soft tissue, cartilage, and medical-grade silicone). Results: The ICSP in the ST was significantly increased after RWM reinforcement for frequencies below 2 kHz. Between 400 and 600 Hz, all three materials demonstrated the highest median pressure increase. The higher the RWM stiffness, the larger the pressure increase: silicone (7 dB) < soft tissue (10 dB) < cartilage (13 dB). The ICSP in the SV was less affected by reinforcement. The highest median pressure increase was 3 dB. The experimental findings can be explained with numerical models of cochlear mechanics. Discussion and conclusions: RWM reinforcement increases the sound pressure in ST at lower frequencies but only has a minor influence on the SV pressure.

scholarly journals The Effects of Round Window Membrane Injury and the Use of a Model Electrode Application on Hearing in Rats

2021 ◽  
pp. 014556132199018
Author(s):  
Murat Koc ◽  
Abdullah Dalgic ◽  
Mehmet Ziya Ozuer
Keyword(s):  
Hearing Loss ◽  
Cochlear Implant ◽  
Round Window ◽  
Mechanical Trauma ◽  
Round Window Membrane ◽  
Albino Rats ◽  
Topical Steroids ◽  
Distortion Product ◽  
Significant Difference ◽  
Group 3

Objective: To investigate the effects of the mechanical trauma to the round window, a model electrode inserted into the scala tympani on the cochlear reserve, and the efficacy of topical steroids in preventing hearing loss. Materials and Methods: 21 male Wistar Albino rats were equally categorized into three groups. In all groups an initial mechanical injury to round window was created. Only subsequent dexamethasone injection was administrated into the cochlea in the subjects of group 2 while a multichannel cochlear implant guide inserted into the cochlea prior to dexamethasone administration for group 3. Distortion product otoacoustic emissions (DPOAEs) were obtained prior to and immediately after the surgical injury, eventually on postoperative seventh day (d 7). Mean signal/noise ratios (S/Ns) obtained at 2000, 3000, and 4000 Hz were calculated. Data sets were compared with non-parametric statistical tests. Results: The early intraoperative mean S/Ns were significantly less than preoperative measurements for group 1 and 2; however, preoperative and postoperative d 7 average S/Ns did not differ. There was statistically significant difference between preoperative, intraoperative and postoperative d 7 average S/Ns for group 3. Conclusion: We observed that hearing was restored approximately to the preoperative levels following early postoperative repair. However, an electrode insertion into the cochlea via round window subsequent to mechanical trauma seems to cause a progressive hearing loss. Therefore, a special care must be taken to avoid the injury to the round window membrane in the course of the placement of a cochlear implant electrode and surgery for the chronic otitis media.

scholarly journals Nasal Morphology and Its Correlation to Craniofacial Morphology in Lateral Cephalometric Analysis

2021 ◽  
Vol 18 (6) ◽  
pp. 3064
Author(s):  
Agnieszka Jankowska ◽  
Joanna Janiszewska-Olszowska ◽  
Katarzyna Grocholewicz
Keyword(s):  
Soft Tissue ◽  
Nasal Bone ◽  
Correlation Coefficients ◽  
Craniofacial Morphology ◽  
Base Angle ◽  
Nasolabial Angle ◽  
Orthodontic Patients ◽  
Nose Shape ◽  
The Relationship ◽  
Spearman’S Correlation

Nose shape, size, and inclination influence facial appearance, but few studies concern the relationship between the nasal profile and craniofacial structures. The objective of this study was to analyze association of nasal cephalometric variables with skeletal structures, age, and sex. Cephalometric and nasal analysis was performed in 386 Polish orthodontic patients (aged 9–25 years). Student t-test and Mann–Whitney test were used to compare quantitative variables and Pearson’s or Spearman’s correlation coefficients—to find correlations. Soft tissue facial convexity angle correlates to Holdaway ratio, ANB (A-Nasion-B), and Wits appraisal. Nasal dorsum axis, nose length, nose depth (1) and nose depth (2), nose hump, lower dorsum convexity, and columella convexity increase with age. Nasal base angle, nasolabial angle, nasomental angle, soft tissue facial convexity and nasal bone angle decrease with age. Nasal base angle and nasomental angle are smaller in females. Thus, a relationship exists between nasal morphology and sagittal jaw configuration. Nasal parameters significantly change with age. Sexual dimorphism characterizes nasal bone angle and nasomental angle.

scholarly journals Cochlear Implantation Following Explorative Tympanotomy in Patients With Sudden Sensorineural Hearing Loss: Surgical Features and Audiological Outcomes

2021 ◽  
pp. 014556132110091
Author(s):  
Robin Rupp ◽  
Joachim Hornung ◽  
Matthias Balk ◽  
Matti Sievert ◽  
Sarina Müller ◽  
...  
Keyword(s):  
Hearing Loss ◽  
Connective Tissue ◽  
Sensorineural Hearing Loss ◽  
Cochlear Implantation ◽  
Round Window ◽  
Sudden Sensorineural Hearing Loss ◽  
Sensorineural Hearing ◽  
Round Window Membrane ◽  
Hearing Results ◽  
Round Window Niche

Objective: To investigate the anatomical status of the round window niche and hearing outcome of cochlear implantation (CI) after explorative tympanotomy (ExT) with sealing of the round window membrane in patients with sudden sensorineural hearing loss at a tertiary referral medical center. Methods: Between January 1, 2007, and July 30, 2020, 1602 patients underwent CI at our department. Out of these, all patients previously treated by ExT with sealing of the round window membrane because of unilateral sudden hearing loss were included in the study. A retrospective chart review was conducted concerning method of round window membrane sealing, intraoperative findings during CI, postoperative imaging, and hearing results. Results: Twenty one patients (9 females; 8 right ears; 54.3 years [± 12.9 years]) underwent ExT with sealing of the round window membrane with subsequent CI after 26.6 months (± 32.9 mo) on average. During CI, in 76% of cases (n = 16), the round window niche was blocked by connective tissue due to the previous intervention but could be removed completely in all cases. The connective tissue itself and its removal had no detrimental effects on the round window membrane. Postoperative computed tomography scan showed no electrode dislocation. Mean postoperative word recognition score after 3 months was 57.4% (± 17.2%) and improved significantly to 73.1% (± 16.4%, P = .005) after 2 years. Conclusion: Performing CI after preceding ExT, connective tissue has to be expected blocking the round window niche. Remaining tissue can be removed safely and does not alter the round window membrane allowing for a proper electrode insertion. Short- and long-term hearing results are satisfactory. Consequently, ExT with sealing of the round window membrane in patients with sudden sensorineural hearing loss does not impede subsequent CI that can still be performed safely.

scholarly journals Stochastic Natural Vibration Analyses of Free-Form Shells

2019 ◽  
Vol 9 (15) ◽  
pp. 3168
Author(s):  
Bingbing San ◽  
Yunlong Ma ◽  
Zhi Xiao ◽  
Dongming Feng ◽  
Liwei Yin
Keyword(s):  
Elastic Modulus ◽  
Shape Optimization ◽  
Shell Thickness ◽  
Natural Vibration ◽  
Natural Frequencies ◽  
Vibration Characteristics ◽  
Free Form ◽  
Probability Models ◽  
Geometric Imperfection ◽  
Natural Vibration Characteristics

This work investigates the natural vibration characteristics of free-form shells when considering the influence of uncertainties, including initial geometric imperfection, shell thickness deviation, and elastic modulus deviation. Herein, free-form shell models are generated while using a self-coded optimization algorithm. The Latin hypercube sampling (LHS) method is used to draw the samplings of uncertainties with respect to their stochastic probability models. ANSYS finite element (FE) software is adopted to analyze the natural vibration characteristics and compute the natural frequencies. The mean values, standard deviations, and cumulative distributions functions (CDFs) of the first three natural frequencies are obtained. The partial correlation coefficient is adopted to rank the significances of uncertainty factors. The study reveals that, for the free-form shells that were investigated in this study, the natural frequencies is a random quantity with a normal distribution; elastic modulus deviation imposes the greatest effect on natural frequencies; shell thickness ranks the second; geometrical imperfection ranks the last, with a much lower weight than the other two factors, which illustrates that the shape of the studied free-form shells is robust in term of natural vibration characteristics; when the supported edges are fixed during the shape optimization, the stochastic characteristics do not significantly change during the shape optimization process.

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