Radiologic Evaluation of the Round Window Niche Configuration: A One-Stop Approach

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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Contribution of auditory nerve fibers to compound action potential of the auditory nerve

Journal of Neurophysiology ◽

10.1152/jn.00738.2013 ◽

2014 ◽

Vol 112 (5) ◽

pp. 1025-1039 ◽

Cited By ~ 109

Author(s):

Jérôme Bourien ◽

Yong Tang ◽

Charlène Batrel ◽

Antoine Huet ◽

Marc Lenoir ◽

...

Keyword(s):

Action Potential ◽

Auditory Nerve ◽

Computational Simulation ◽

Round Window ◽

Hearing Threshold ◽

Compound Action Potential ◽

Nerve Fibers ◽

Auditory Nerve Fibers ◽

Round Window Niche ◽

Compound Action

Sound-evoked compound action potential (CAP), which captures the synchronous activation of the auditory nerve fibers (ANFs), is commonly used to probe deafness in experimental and clinical settings. All ANFs are believed to contribute to CAP threshold and amplitude: low sound pressure levels activate the high-spontaneous rate (SR) fibers, and increasing levels gradually recruit medium- and then low-SR fibers. In this study, we quantitatively analyze the contribution of the ANFs to CAP 6 days after 30-min infusion of ouabain into the round window niche. Anatomic examination showed a progressive ablation of ANFs following increasing concentration of ouabain. CAP amplitude and threshold plotted against loss of ANFs revealed three ANF pools: 1) a highly ouabain-sensitive pool, which does not participate in either CAP threshold or amplitude, 2) a less sensitive pool, which only encoded CAP amplitude, and 3) a ouabain-resistant pool, required for CAP threshold and amplitude. Remarkably, distribution of the three pools was similar to the SR-based ANF distribution (low-, medium-, and high-SR fibers), suggesting that the low-SR fiber loss leaves the CAP unaffected. Single-unit recordings from the auditory nerve confirmed this hypothesis and further showed that it is due to the delayed and broad first spike latency distribution of low-SR fibers. In addition to unraveling the neural mechanisms that encode CAP, our computational simulation of an assembly of guinea pig ANFs generalizes and extends our experimental findings to different species of mammals. Altogether, our data demonstrate that substantial ANF loss can coexist with normal hearing threshold and even unchanged CAP amplitude.

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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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Significance of round window niche drilling for cochlear implant surgery

Indian Journal of Otology ◽

10.4103/indianjotol.indianjotol_43_17 ◽

2017 ◽

Vol 23 (3) ◽

pp. 141 ◽

Cited By ~ 2

Author(s):

Deepak Dalmia ◽

SanjayaKumar Behera

Keyword(s):

Cochlear Implant ◽

Round Window ◽

Implant Surgery ◽

Cochlear Implant Surgery ◽

Round Window Niche

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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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An optical coherence tomography study for imaging the round window niche and the promontorium tympani

10.1117/12.848384 ◽

2010 ◽

Author(s):

T. Just ◽

E. Lankenau ◽

G. Hüttmann ◽

H. W. Pau

Keyword(s):

Optical Coherence Tomography ◽

Round Window ◽

Optical Coherence ◽

Round Window Niche

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Microfissure between the round Window Niche and Posterior Canal Ampulla

Annals of Otology Rhinology & Laryngology ◽

10.1177/000348947708600108 ◽

1977 ◽

Vol 86 (1) ◽

pp. 49-57 ◽

Cited By ~ 18

Author(s):

Yasumasa Okano ◽

Eugene N. Myers ◽

David R. Dickson

Keyword(s):

Round Window ◽

Pathological Finding ◽

Anatomical Structure ◽

Fetal Life ◽

Human Fetuses ◽

Posterior Canal ◽

Mesenchymal Tissue ◽

One Year ◽

Round Window Niche ◽

Temporal Bones

The microfissure between the round window niche and the posterior canal ampulla was examined in fetal, child, and adult human temporal bones. The communication which was filled with mesenchymal tissue and blood vessels extending from the middle ear, was observed between the round window niche and the posterior canal ampulla in 10 to 15-week human fetuses. The mesenchymal tissue in the communication was replaced by cartilage with advancing age of the fetus. No communication was observed at birth. From newborn to 12 months of age, no microfissure was observed. After one year of age, the microflssure was first observed and the frequency of the observation increased with increasing age of the patient. After six years of age, the microfissure was observed bilaterally in 100% of cases studied. The microflssure has its origin from the communication between the round window niche and the posterior canal ampulla in fetal life, and is a normal developmental and anatomical structure, and not a pathological finding.

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Locating the scala media in the fixed human temporal bone for therapeutic access: a preliminary study

The Journal of Laryngology & Otology ◽

10.1017/s0022215106002520 ◽

2006 ◽

Vol 120 (11) ◽

pp. 914-915 ◽

Cited By ~ 1

Author(s):

H Pau ◽

P Fagan ◽

S Oleskevich

Keyword(s):

Temporal Bone ◽

Round Window ◽

Oval Window ◽

Horizontal Line ◽

Point Of Entry ◽

Anterior Edge ◽

Human Temporal Bone ◽

Round Window Niche ◽

Temporal Bones ◽

A Site

Objective: To investigate the location of the scala media in relation to the round window niche in human temporal bones.Design: Ten human temporal bones were investigated by radical mastoidectomy and promontory drill-out.Setting: Temporal bone laboratory.Outcome measures: The distance from the scala media to the anterior edge of the round window niche, measured by Fisch's stapedectomy measuring cylinders.Results: The scala media was identified at the transection point of a vertical line 1.6 to 2.2 mm (mean=1.8 mm; standard deviation=0.2) anterior to the anterior edge of the round window niche and a horizontal line 0.2 mm inferior to the lower border of the oval window.Conclusion: This report demonstrates the point of entry into the scala media via the promontory in fixed temporal bone models, which may provide a site of entry for stem cells and gene therapy insertion.

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