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.

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

1987 ◽  
Vol 101 (2) ◽  
pp. 97-102 ◽  
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.

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

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.

scholarly journals Predicting Round Window Visibility During Cochlear Implantation Using High Resolution CT Scan

2018 ◽  
pp. 15-15 ◽  
Author(s):  
Saad Elzayat ◽  
◽  
Mahmoud Mandour ◽  
Rasha Lotfy ◽  
Ali Mahrous ◽  
...  
Keyword(s):  
High Resolution ◽  
Ct Scan ◽  
Cochlear Implantation ◽  
Round Window ◽  
High Resolution Ct

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.

Endoscopic visualisation of the round window during cochlear implantation

2020 ◽  
Vol 134 (3) ◽  
pp. 219-221 ◽  
Author(s):  
A Jain ◽  
R Sharma ◽  
J C Passey ◽  
R Meher ◽  
R Bansal
Keyword(s):  
Middle Ear ◽  
Cochlear Implantation ◽  
Round Window ◽  
Electrode Array ◽  
Round Window Membrane ◽  
Window Region ◽  
Round Window Niche ◽  
Window Approach ◽  
Maximum Exposure

AbstractBackgroundEndoscopes provide a magnified view of the middle ear and visualisation of hidden areas. Otoendoscopes facilitate excellent visualisation of the round window niche during cochlear implantation.ObjectiveTo compare microscopic and endoscopic visualisation of the round window membrane during cochlear implantation in 20 patients.MethodsTwenty patients who underwent cochlear implantation were included in the study. After maximum exposure of the round window, the accessibility of the round window membrane was graded according to the St Thomas Hospital classification, first by microscope and then by endoscope.ResultsWith the use of the endoscope, visualisation of the round window membrane improved in all the patients as compared to the microscope. The electrode array was inserted via a round window or extended round window approach in all but two cases; the latter cases required bony cochleostomy because of unfavourable anatomy.ConclusionThe main benefit of endoscope-assisted cochlear implantation is improved visibility of the round window region.

scholarly journals Bilateral Oval and Round Window Atresia on CT Temporal Bone: A Rare Anomaly Clinically Mimicking Otosclerosis in an Adult

2019 ◽  
Vol 2019 ◽  
pp. 1-5
Author(s):  
Manzoor Ahmed ◽  
Yogesh Indrasen More ◽  
Shaik Irfan Basha
Keyword(s):  
Hearing Loss ◽  
High Resolution ◽  
Temporal Bone ◽  
Conductive Hearing Loss ◽  
Round Window ◽  
Adult Case ◽  
High Resolution Ct ◽  
Rare Anomaly ◽  
Temporal Bones ◽  
Conductive Hearing

We present a rare adult case of bilateral oval and round window atresia. Clinical and audiologic findings were suggestive of otosclerosis. High resolution CT Temporal bones showed unequivocal findings of bilateral oval and round window atresia. Atresia of these windows is a rare temporal bone anomaly. Presentation as an adult can confound the clinicians and warranting a closer look on the CT for atretic windows and subtle signs of otosclerosis in patients with conductive hearing loss.

scholarly journals Effect of Experimentally Induced Otitis Media on Cochlear Implants

1987 ◽  
Vol 96 (2) ◽  
pp. 174-177 ◽  
Author(s):  
Burkhard K-H. Franz ◽  
Graeme M. Clark ◽  
David M. Bloom
Keyword(s):  
Horseradish Peroxidase ◽  
Cochlear Implants ◽  
Round Window ◽  
Round Window Membrane ◽  
Group A Streptococci ◽  
Scala Tympani ◽  
Tracer Studies ◽  
Entry Points ◽  
Group A ◽  
Round Window Niche

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.

Sign in / Sign up

Export Citation Format

Share Document