Effect of Experimentally Induced Otitis Media on Cochlear Implants

Cat cochleas implanted with scala tympani prostheses were investigated histologically after inoculating the bullae with a suspension of group a streptococci. The prosthesis was passed through the round window membrane in one ear. In the other the prosthesis bypassed the round window via an opening anteroinferior to the round window niche. Before death, horseradish peroxidase was administered as a tracer for possible pathways of infection. Results showed that group a streptococci were pathogenic to the cat and caused inflammation in the bulla. The unimplanted round window membrane and the seals around the electrode entry points prevented infection from entering the cochlea. The seals around electrodes inserted either through the round window membrane or an opening drilled anteroinferior to the niche were equally effective. The horseradish peroxidase tracer studies showed, however, that a gap existed between the electrode and membranous seal, and this could be a potentially vulnerable site under certain conditions. Drilling an anteroinferior opening into the cochlea resulted in bony sequestra entering the cochlea. This can be avoided by blue-lining the opening and removing bone with picks before making an opening through the endosteum.

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Surgical anatomy of the round window with special reference to cochlear implantation

The Journal of Laryngology & Otology ◽

10.1017/s0022215100101343 ◽

1987 ◽

Vol 101 (2) ◽

pp. 97-102 ◽

Cited By ~ 37

Author(s):

Burkhard K. H. Franz ◽

Graeme M. Clark ◽

David M. Bloom

Keyword(s):

Cochlear Implant ◽

Special Reference ◽

Cochlear Implantation ◽

Round Window ◽

Surgical Anatomy ◽

Round Window Membrane ◽

Scala Tympani ◽

Good View ◽

Posterior Tympanotomy ◽

Round Window Niche

AbstractWhen the multi-channel cochlear implant electrode is inserted into the scala tympani through the round window the operation is best performed via a posterior tympanotomy. The view of the round window membrane, however, is incomplete because of its orientation and the fact that it has a conical shape. Nevertheless, a good view along the basal turn is obtained after the antero-inferior overhang of the round window niche and the crista fenestrae have been removed. It might be damaging to drill away the postero-superior overhang as the osseous spiral lamina lies extremely close to the round window membrane.

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

Audiology and Neurotology ◽

10.1159/000471840 ◽

2017 ◽

Vol 22 (1) ◽

pp. 50-55 ◽

Cited By ~ 4

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.

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

Ear Nose & Throat Journal ◽

10.1177/01455613211009141 ◽

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.

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Comparison of Round Window Anatomy between Pediatric and Adult Population: A Perspective from Cochlear Implantation Surgery

Journal of Institute of Medicine ◽

10.3126/jiom.v42i3.37573 ◽

2020 ◽

Vol 42 (3) ◽

pp. 23-25

Author(s):

Rabindra B Pradhananga ◽

Bigyan R Gyawali ◽

Pabina Rayamajhi

Keyword(s):

Cochlear Implantation ◽

Adult Population ◽

Round Window ◽

Round Window Membrane ◽

Institute Of Medicine ◽

Statistical Association ◽

Complex Anatomy ◽

Wide Range ◽

Posterior Tympanotomy ◽

Round Window Niche

Introduction The round window is thought to be an ideal port for inserting electrodes during cochlear implantation. Considering its complex anatomy with an individual variation, this study aims to review the anatomy of round window based on the visibility of round window niche and round window membrane via posterior tympanotomy in pediatric and adult population who underwent cochlear implantation. MethodsThis was a retrospective observational study conducted at the Department of ENT-HNS, Institute of Medicine, Kathmandu, Nepal. Surgical notes of adult (>15 years) and pediatric cases (<15years) who underwent primary cochlear implantation from January 2015 to January 2018 were assessed for different grading of round window niche and round window membrane visibility via posterior tympanotomy. Cases with revision surgery and with incomplete documentation of intra-operative findings were excluded from the study. Statistical analysis was done using SPSS software version 25. We used Chi-square and Fisher’s exact tests to analyze the statistical association. ResultsType B round window niche (partially visible) was the most common variant seen in the pediatric group while in adults, both Type B (partially visible) and Type C (fully visible) round window niche were common. Compared to the adults, the pediatric group had good visibility of RWM. However, there was no statistical association between these observations. ConclusionThe round window has a wide range of anatomical variations with different levels of visibility of RWN and RWM in the different age groups. Although statistically insignificant, RWM visibility seemed to be better in pediatric cases compared to adults.

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‘Soft reinforcement’ of the round window for superior semi-circular canal dehiscence syndrome

The Journal of Laryngology & Otology ◽

10.1017/s0022215120000353 ◽

2020 ◽

Vol 134 (4) ◽

pp. 366-368 ◽

Cited By ~ 1

Author(s):

A Gona ◽

J S Phillips

Keyword(s):

Case Report ◽

Round Window ◽

Invasive Technique ◽

Round Window Membrane ◽

Spatial Disorientation ◽

Migraine Headaches ◽

Vestibular Symptoms ◽

Round Window Niche ◽

Canal Syndrome ◽

Canal Dehiscence

AbstractBackgroundIndividuals with superior semi-circular canal syndrome often describe vestibular symptoms elicited by loud sounds, as well as other pressure-induced symptoms. They also often report other symptoms, including autophony, hyperacusis, cognitive dysfunction, spatial disorientation, anxiety and migraine headaches. Symptoms occur due to the presence of a ‘third window’ created by the dehiscence of the superior semi-circular canal. This case report describes a minimally invasive technique to provide soft reinforcement of the round window.Case reportOur patient underwent a permeatal procedure whereby the tympanic membrane was raised to allow inspection of the middle ear. The round window niche was identified and the round window membrane was reinforced with fat. The mucosa of the bony meatus leading to the round window was then disrupted before the application of a double layer of perichondrium to allow further reinforcement.ConclusionThe case provides support for the use of ‘soft reinforcement’ as a simple and effective technique to treat the symptoms of superior canal dehiscence syndrome.

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Secondary Degeneration of Auditory Neurons after Topical Aminoglycoside Administration in a Gerbil Model

BioMed Research International ◽

10.1155/2018/9158187 ◽

2018 ◽

Vol 2018 ◽

pp. 1-10

Author(s):

Jae-Hun Lee ◽

Min Young Lee ◽

Phil-Sang Chung ◽

Jae Yun Jung

Keyword(s):

Cochlear Implants ◽

Hair Cells ◽

Round Window ◽

Research Area ◽

Round Window Membrane ◽

Auditory Neurons ◽

Secondary Degeneration ◽

Hearing Research ◽

Practical Model ◽

Ototoxic Drug

Hair cells in the cochlea can be damaged by various causes. Damaged hair cells can lead to additional destruction of parts of the auditory afferent pathway sequentially, which is called secondary degeneration. Recently, researches regarding cochlear implants have been actively carried out for clinical purposes; secondary degeneration in animals is a much more practical model for identifying the prognosis of cochlear implants. However, an appropriate model for this research is not established yet. Thus, we developed a secondary degeneration model using an ototoxic drug. 35 gerbils were separated into four different groups and kanamycin was applied via various approaches. ABR was measured several times after drug administration. SGCs were also counted to identify any secondary degeneration. The results showed that outer and inner HCs were damaged in all kanamycin-treated groups. Twelve weeks after kanamycin treatment, the round window membrane injection group showed severe subject differences in hair cells and SGC damage, whereas the gelfoam group showed consistent and severe damage in hair cells and SGCs. In this study, we successfully induced secondary degeneration in hair cells in a gerbil model. This model can be used for various purposes in the hearing research area either for treatment or for preservation.

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Mechanics of Type IV Tympanoplasty: Experimental Findings and Surgical Implications

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348949710600110 ◽

1997 ◽

Vol 106 (1) ◽

pp. 49-60 ◽

Cited By ~ 12

Author(s):

Saumil N. Merchant ◽

Michael E. Ravicz ◽

John J. Rosowski

Keyword(s):

Silicone Rubber ◽

Round Window ◽

Annular Ligament ◽

Round Window Membrane ◽

Theoretic Model ◽

Hearing Level ◽

Type Iv ◽

Fascia Graft ◽

Air Space ◽

Round Window Niche

In a type IV tympanoplasty, the stapes footplate is directly exposed to incoming sound while the round window is “shielded,” usually with a fascia graft. Postoperative hearing results are quite variable, with air-bone gaps ranging from 10 to 60 dB. A cadaveric human temporal bone preparation was developed to investigate the middle ear mechanics of this operation to identify causes of variable results and to test predictions of a recently described theoretic model of type IV tympanoplasty. The ear canal, tympanic membrane, malleus, and incus were removed so as to expose the stapes and round window to the sound stimulus. A “cavum minor” chamber (air space adjacent to the round window) was constructed around the round window niche. The round window could be isolated from sound by placing an acoustic shield over this chamber. The mechanical properties of the shield, cavum minor, annular ligament, and round window membrane were varied experimentally. Stapes velocity as determined by an optical motion sensor was used as a measure of hearing level. The largest stapes velocity occurred with a mobile stapes and round window, a stiff shield, and a well-aerated cavum minor. Partial fixation of the stapes or round window caused a decrease in stapes velocity. Acoustic shields of conchal cartilage or Silastic silicone rubber sheeting (approximately 1 mm thick) provided near-optimal shielding. A temporalis fascia shield resulted in a stapes velocity 10 to 20 dB less than that seen with a cartilage or Silastic silicone rubber shield at low frequencies. A cavum minor air space as small as 16 μL was sufficient for unrestricted stapes motion, provided the air was in contact with the round window membrane. These results qualitatively matched predictions of our model, but there were some quantitative differences. The clinical implications of our results are that in order to optimize postoperative hearing, the surgeon should 1) preserve normal stapes mobility, preferably by covering the footplate with a very thin split-thickness skin graft, not a fascia graft; 2) reinforce a fascia shield with cartilage or Silastic silicone rubber; 3) create conditions that promote aeration of the round window niche; and 4) preserve the mobility of the round window membrane.

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Histopathological and audiological effects of mechanical trauma associated with the placement of an intracochlear electrode, and the benefit of corticosteroid infusion: prospective animal study

The Journal of Laryngology & Otology ◽

10.1017/s002221511400156x ◽

2014 ◽

Vol 128 (8) ◽

pp. 702-708 ◽

Cited By ~ 5

Author(s):

G Malkoc ◽

A Dalgic ◽

M Koc ◽

T Kandogan ◽

S Korkmaz ◽

...

Keyword(s):

Hearing Loss ◽

Topical Corticosteroid ◽

Animal Study ◽

Hair Cells ◽

Normal Saline ◽

Round Window ◽

Osmotic Pump ◽

Mechanical Trauma ◽

Round Window Membrane ◽

Scala Tympani

AbstractObjective:This study aimed to present the histopathological and audiological effects of mechanical trauma associated with the placement of a model electrode in the scala tympani in rats, and the effects of continuous topical corticosteroid application.Method:The study comprised three groups of rats. The round window membrane was perforated in all three groups and a model electrode was inserted in the round window. Group one received no further treatments. Groups two and three also had an intrathecal microcatheter compatible with a mini-osmotic pump inserted; in group two this was used to release normal saline and in group three the pump released 400 µg/ml dexamethasone.Results:Dexamethasone infusion given after implantation of the intracochlear model electrode was more effective for preventing hearing loss than the administration of just one dose of dexamethasone.Conclusion:The findings suggest that continuous dexamethasone infusion is beneficial for preventing the loss of hair cells and neurons associated with early and late periods of intracochlear electrode trauma.

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