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.

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.

Computer-Aided Three-Dimensional Reconstruction and Measurement of the round Window and its Membrane

1989 ◽  
Vol 101 (5) ◽  
pp. 517-521 ◽  
Author(s):  
Haruo Takahashi ◽  
Akira Takagi ◽  
Isamu Sando
Keyword(s):  
Surface Area ◽  
Round Window ◽  
Three Dimensional ◽  
Round Window Membrane ◽  
Reconstruction Method ◽  
Three Dimensional Reconstruction ◽  
Maximal Diameter ◽  
Computer Aided ◽  
Dimensional Reconstruction ◽  
Temporal Bones

This study was performed to clarify the complex three-dimensional shape of the round window and its membrane, and to measure these structures by using the computer-aided three-dimensional reconstruction method we developed. The equipment used included a personal computer, a high-resolution, 14-Inch color monitor, and a digitizer. Materials consisted of five normal temporal bones obtained from five individuals with negative otologic histories who had been 5 months and 14, 15, 18, and 59 years old at death. Round window membranes were found to be convex to the middle ear side when viewed in the coronal plane, but to be concave when viewed in the sagittal plane; thus the membrane in most cases seemed to be shaped like a saddle, tapered toward the vestibular end. The average maximal diameter, sagittal length, horizontal width, and surface area of the round window were 2.32 ± 0.19 mm, 2.08 ± 0.22 mm, 1.76 ± 0.10 mm, and 2.70 ± 0.43 mm2, respectively. The average surface area of the round window membrane was 2.98 ± 0.43 mm2.

scholarly journals Differential Intracochlear Sound Pressure Measurements in Human Temporal Bones with an Off-the-Shelf Sensor

2016 ◽  
Vol 2016 ◽  
pp. 1-10 ◽  
Author(s):  
Martin Grossöhmichen ◽  
Rolf Salcher ◽  
Klaus Püschel ◽  
Thomas Lenarz ◽  
Hannes Maier
Keyword(s):  
Mechanical Stimulation ◽  
Pressure Sensor ◽  
Sound Pressure ◽  
Ossicular Chain ◽  
Acoustic Stimulation ◽  
Pressure Measurements ◽  
Output Level ◽  
Custom Made ◽  
Temporal Bones

The standard method to determine the output level of acoustic and mechanical stimulation to the inner ear is measurement of vibration response of the stapes in human cadaveric temporal bones (TBs) by laser Doppler vibrometry. However, this method is reliable only if the intact ossicular chain is stimulated. For other stimulation modes an alternative method is needed. The differential intracochlear sound pressure between scala vestibuli (SV) and scala tympani (ST) is assumed to correlate with excitation. Using a custom-made pressure sensor it has been successfully measured and used to determine the output level of acoustic and mechanical stimulation. To make this method generally accessible, an off-the-shelf pressure sensor (Samba Preclin 420 LP, Samba Sensors) was tested here for intracochlear sound pressure measurements. During acoustic stimulation, intracochlear sound pressures were simultaneously measurable in SV and ST between 0.1 and 8 kHz with sufficient signal-to-noise ratios with this sensor. The pressure differences were comparable to results obtained with custom-made sensors. Our results demonstrated that the pressure sensor Samba Preclin 420 LP is usable for measurements of intracochlear sound pressures in SV and ST and for the determination of differential intracochlear sound pressures.

Temporal Bone Pathology in Scuba Diving Deaths

1993 ◽  
Vol 109 (3) ◽  
pp. 514-521 ◽  
Author(s):  
Patrick J. Antonelli ◽  
G. Joseph Parell ◽  
Gary D. Becker ◽  
Michael M. Paparella
Keyword(s):  
Inner Ear ◽  
Temporal Bone ◽  
Round Window ◽  
Scuba Diving ◽  
Round Window Membrane ◽  
Bone Pathology ◽  
Rapid Ascent ◽  
Temporal Bones ◽  
Inner Ear Damage ◽  
Air Cells

Scuba diving has long been associated with otologic injuries; however, little is known about temporal bone pathology in diving-related deaths. We examined 18 temporal bones from 11 divers who died, primarily from complications of rapid ascent. Bleeding into the middle ear and mastoid air cells was nearly universal. Inner ear damage included hemorrhage around Reissner's membrane and the round window membrane and rupture of the utricle and saccule. Most of the observed inner ear damage was not surgically treatable. (OTOLARYNGOL HEAD NECK SURG 1993;109:514-21.)

Electrocochleography in the Presence and Absence of Perilymphatic Fistula

1992 ◽  
Vol 101 (5) ◽  
pp. 403-407 ◽  
Author(s):  
Kathleen C. M. Campbell ◽  
Michael M. Savage ◽  
Lee A. Harker
Keyword(s):  
Sound Pressure Level ◽  
Guinea Pigs ◽  
Sound Pressure ◽  
Amplitude Ratio ◽  
Round Window ◽  
Tone Burst ◽  
Pressure Level ◽  
Round Window Membrane ◽  
Perilymphatic Fistula ◽  
Summating Potential

The purpose of the present study was to evaluate the effect of an acute perilymphatic fistula on the amplitude ratio (SP/AP) of the summating potential (SP) and action potential (AP). The effect of the acute fistula on AP threshold was also addressed. Electrocochleo-graphic recordings were obtained before and immediately after surgical laceration of the round window membrane in 19 guinea pigs. Stimuli comprised clicks and 2,000-Hz and 8,000-Hz tone bursts, presented initially at 100 dB peak equivalent sound pressure level and in descending 10-dB steps. After fistula induction the SP/AP significantly increased for the click and 8,000-Hz tone burst stimuli but not for the 2,000-Hz tone burst stimuli. No significant change in AP threshold occurred. These findings suggest that the SP/AP may be sensitive to perilymphatic fistula, at least in guinea pigs. The changes in the SP/AP do not appear to be related to changes in threshold.

scholarly journals Anatomical Study of the Facial Recess with Implications in Round Window Visibility for Cochlear Implantation: Personal Observations and Review of the Literature

2019 ◽  
Vol 23 (03) ◽  
pp. e281-e291 ◽  
Author(s):  
Shraddha Jain ◽  
PT Deshmukh ◽  
Pooja Lakhotia ◽  
Sanika Kalambe ◽  
Deepshikha Chandravanshi ◽  
...  
Keyword(s):  
Cochlear Implantation ◽  
Round Window ◽  
Round Window Membrane ◽  
Chorda Tympani Nerve ◽  
Maximum Width ◽  
Facial Recess ◽  
Average Maximum ◽  
Mean Width ◽  
The Mean ◽  
Temporal Bones

Introduction Posterior tympanotomy through facial recess (FR) is the conventional and most preferred approach to facilitate cochlear implantation, especially when the electrode is inserted through the round window. The complications of the FR approach can be minimized by proper understanding of the anatomy of the FR. Objective The present study was undertaken to assess the various parameters of FR and round window visibility, which may be of relevance for cochlear implant surgery. Methods Thirty-five normal wet human cadaveric temporal bones were studied by dissection for anatomy of FR and posterior tympanum. Photographs were taken with an 18 megapixels digital camera, which were then imported to a computer to determine various parameters. Results The mean distance from the take-off point/crotch of the chorda tympani nerve (CTN) to the stylomastoid foramen was 4.08 ± 0.8 mm (range of 2.06 - 5.5 mm). The variations in the course of the CTN included origin at the level of the lateral semicircular canal. The mean chorda-facial angle in our study was 26.91° ± 1.19°, with a range of 25° to 28.69°. The mean FR length ranged between 9.4 mm and 18.56 mm (mean of 12.41 ± 2.91mm) and varied with the origin of the CTN and pneumatization of temporal bone. The average maximum width of the FR was 2.93 ± 0.4 mm (range 2.24–3.45 mm) and the mean width of the FR at the level of the round window was 2.65 ± 0.41 mm. Conclusion The FR approach provides good access to the round window membrane in all cases. In some cases, table adjustment is required.

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 Evaluation of Intracochlear Trauma Caused by Insertion of Cochlear Implant Electrode Arrays through Different Quadrants of the Round Window

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Graziela de Souza Queiroz Martins ◽  
Rubens Vuono Brito Neto ◽  
Robinson Koji Tsuji ◽  
Eloisa Maria Mello Santiago Gebrim ◽  
Ricardo Ferreira Bento
Keyword(s):  
Cochlear Implant ◽  
Round Window ◽  
Electrode Array ◽  
Hearing Preservation ◽  
Round Window Membrane ◽  
Residual Hearing ◽  
Electrode Arrays ◽  
Minimal Trauma ◽  
Electrode Insertion ◽  
Temporal Bones

Hypothesis. This study aimed to evaluate whether there is a difference in the degree of intracochlear trauma when the cochlear implant electrode arrays is inserted through different quadrants of the round window membrane.Background. The benefits of residual hearing preservation in cochlear implant recipients have promoted the development of atraumatic surgeries. Minimal trauma during electrode insertion is crucial for residual hearing preservation.Methods. In total, 25 fresh human temporal bones were subjected to mastoidectomy and posterior tympanotomy. The cochlear implant electrode array was inserted through the anterosuperior quadrant of the round window membrane in 50% of the bones and through the anteroinferior quadrant in the remaining 50%. The temporal bones were dehydrated, embedded in epoxy, serially polished, stained, viewed through a stereomicroscope, and photographed with the electrode arraysin situ. The resulting images were analyzed for signs of intracochlear trauma.Results. Histological examinations revealed varying degrees of damage to the intracochlear structures, although the incidence and severity of intracochlear trauma were not influenced by the quadrant of insertion.Conclusions. The incidence and severity of intracochlear trauma were similar in all samples, irrespective of electrode array insertion through the anterosuperior or anteroinferior quadrant of the round window membrane.

The Crista Fenestra and Its Impact on the Surgical Approach to the Scala Tympani during Cochlear Implantation

2017 ◽  
Vol 22 (1) ◽  
pp. 50-55 ◽  
Author(s):  
Roberto D. Angeli ◽  
Joel Lavinsky ◽  
Enio T. Setogutti ◽  
Luiz Lavinsky
Keyword(s):  
High Resolution ◽  
Cochlear Implantation ◽  
Round Window ◽  
Ct Scanning ◽  
Round Window Membrane ◽  
Scala Tympani ◽  
High Resolution Computed Tomography ◽  
High Resolution Ct ◽  
Round Window Niche ◽  
Temporal Bones

Objective: The aim of this work was to describe the dimensions of the crista fenestra and determine its presence by means of high-resolution computed tomography (CT) for the purpose of cochlear implantation via the round window approach. Methods: A series of 10 adult human temporal bones underwent high-resolution CT scanning and were further dissected for microscopic study of the round window niche. Results: In all of the specimens, the round window membrane was fully visualized after the complete removal of bony overhangs. The crista fenestra was identified as a sharp bony crest located in the anterior and inferior borders of the niche; its area ranged from 0.28 to 0.80 mm2 (mean 0.51 ± 0.18). The proportion of the area occupied by the crista fenestra in the whole circumference of the round window ranged from 23 to 50% (mean 36%). We found a moderate positive correlation between the area of the niche and the dimensions of the crista fenestra (Spearman rho: 0.491). In every case, high-resolution CT scanning was unable to determine the presence of the crista fenestra. Conclusion: The crista fenestra occupies a variable but expressive area within the bony round window niche. Narrower round window niches tended to house smaller crests. The presence of the crista fenestra is an important obstacle to adequate access to the scala tympani. Nevertheless, a high-resolution CT scan provides no additional preoperative information with regard to its presence for the purpose of surgical access to the scala tympani via the round window niche.

Occlusion of the round window: a novel way to treat hyperacusis symptoms in superior semicircular canal dehiscence syndrome

2013 ◽  
Vol 127 (7) ◽  
pp. 705-707 ◽  
Author(s):  
A Nikkar-Esfahani ◽  
D Whelan ◽  
A Banerjee
Keyword(s):  
Semicircular Canal ◽  
Round Window ◽  
Round Window Membrane ◽  
Superior Semicircular Canal Dehiscence ◽  
Tullio Phenomenon ◽  
Superior Semicircular Canal ◽  
Case Surgery ◽  
Post Operation ◽  
Round Window Niche ◽  
Canal Dehiscence

AbstractBackground:Conductive hyperacusis in superior semicircular canal dehiscence syndrome occurs due to the presence of a ‘third window’ created by the dehiscence. Reversible blocking of the round window can, in theory, cause a reduction in the compression-related volume displacement, and thereby minimise symptoms of conductive hyperacusis. This study describes a technique of permeatal blocking of the round window.Method:The tympanomeatal flap is elevated and the round window niche is identified. The round window membrane is subsequently identified and occluded with bone wax, muscle and fascia, in three separate layers. Finally, the tympanomeatal flap is reflected, and an ear wick is inserted.Results:Two patients who underwent the procedure reported a reduction in symptoms. Importantly, no Tullio phenomenon was reported post-operation.Conclusion:Blocking of the round window can be used to control symptoms of superior semicircular canal dehiscence syndrome in patients who present solely with symptoms of conductive hyperacusis. This technique provides an alternative to resurfacing techniques. The procedure is simple to perform, reversible and can be undertaken as day-case surgery.

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