Surgical considerations during cochlear implantation: the utility of temporal bone computed tomography

2021 ◽  
pp. 1-8
Author(s):  
Beomcho Jun ◽  
Sunwha Song
Keyword(s):  
Computed Tomography ◽  
Temporal Bone ◽  
Cochlear Implantation ◽  
Round Window ◽  
Three Dimensional ◽  
Electrode Placement ◽  
Posterior Tympanotomy ◽  
Electrode Insertion ◽  
Window Approach ◽  
Bone Structures

Abstract Objective This paper describes the construction of portals for electrode placement during cochlear implantation and emphasises the utility of pre-operative temporal bone three-dimensional computed tomography. Methods Temporal bone three-dimensional computed tomography was used to plan portal creation for electrode insertion. Results Pre-operative temporal bone three-dimensional computed tomography can be used to determine the orientation of temporal bone structures, which is important for mastoidectomy, posterior tympanotomy and cochleostomy, and when using the round window approach. Conclusion It is essential to create appropriate portals (from the mastoid cortex to the cochlea) in a step-by-step manner, to ensure the safe insertion of electrodes into the scala tympani. Pre-operative three-dimensional temporal bone computed tomography is invaluable in this respect.

scholarly journals HRCT Correlation with Round Window Identification during Cochlear Implantation in Children

2014 ◽  
Vol 4 ◽  
pp. 70 ◽  
Author(s):  
Sai Kiran Pendem ◽  
Rajeswaran Rangasami ◽  
Ravi Kumar Arunachalam ◽  
Venkata Sai Pulivadulu Mohanarangam ◽  
Paarthipan Natarajan
Keyword(s):  
Temporal Bone ◽  
Cochlear Implantation ◽  
Round Window ◽  
Oval Window ◽  
Significant Difference ◽  
Posterior Tympanotomy ◽  
Hrct Temporal Bone ◽  
Round Window Niche ◽  
The Right ◽  
A Prospective Study

Objective: To determine the accuracy of High Resolution Computer Tomography (HRCT) temporal bone measurements in predicting the actual visualization of round window niche as viewed through posterior tympanotomy (i.e. facial recess). Materials and Methods: This is a prospective study of 37 cochlear implant candidates, aged between 1and 6 years, who were referred for HRCT temporal bone during the period December 2013 to July 2014. Cochlear implantation was done in 37 children (25 in the right ear and 12 in the left ear). The distance between the short process of incus and the round window niche and the distance between the oval window and the round window niche were measured preoperatively on sub-millimeter (0.7 mm) HRCT images. We classified the visibility of round window niche based on the surgical view (i.e. through posterior tympanotomy) during surgery into three types: 1) Type 1- fully visible, 2) Type 2- partially visible, and 3) Type 3- difficult to visualize. The preoperative HRCT measurements were used to predict the type of visualization of round window niche before surgery and correlated with the findings during surgery. Results: The mean and standard deviation for the distance between the short process of incus and the round window niche and for the distance between the oval window and the round window niche for Types 1, 2, and 3 were 8.5 ± 0.2 mm and 3.2 ± 0.2 mm, 8.0 ± 0.4 mm and 3.8 ± 0.2 mm, 7.5 ± 0.2 mm and 4.4 ± 0.2 mm respectively, and showed statistically significant difference (P < 0.01) between them. The preoperative HRCT measurements had a sensitivity and specificity of 92.3% and 96.2%, respectively, in determining the actual visualization of round window niche. Conclusion: This study shows preoperative HRCT temporal bone measurements are useful in predicting the actual visualization of round window niche as viewed through posterior tympanotomy.

Comparative evaluation of round window niche accessibility pre-operatively on high-resolution computed tomography of the temporal bone with intra-operative findings

2019 ◽  
Vol 133 (7) ◽  
pp. 575-579 ◽  
Author(s):  
R Sharma ◽  
R Meher ◽  
J C Passey ◽  
J Kumar ◽  
A Gupta ◽  
...  
Keyword(s):  
Computed Tomography ◽  
High Resolution ◽  
Temporal Bone ◽  
Round Window ◽  
Type I ◽  
Significant Finding ◽  
High Resolution Computed Tomography ◽  
Posterior Tympanotomy ◽  
Round Window Niche ◽  
Operative Findings

AbstractObjectiveTo compare round window niche visibility as seen endoscopically during cochlear implant surgery with pre-operative high-resolution computed tomography of the temporal bone.MethodsNineteen patients scheduled for cochlear implantation, aged 2–20 years, were referred for computed tomography from October 2016 to March 2018. Angles were measured between the lines passing through the mid-sagittal plane and cochlear basal turn on the scans. Endoscopic round window niche visibility during posterior tympanotomy was categorised as: type I = 100 per cent, type IIa = more than 50 per cent, type IIb = less than 50 per cent or type III = 0 per cent. Pre-operative computed tomography measurements were used to predict round window niche visibility before surgery and correlated with intra-operative findings.ResultsThe mean (range) of pre-operative angles on computed tomography for endoscopic visibility types I, IIa and IIb, were 64.06° (61.16–69.37°), 63.81° (58.61–71.35°) and 56.48° (50.37–59.05°), respectively, a statistically significant finding (one-way analysis of variance test, p = 0.016).ConclusionPre-operative high-resolution temporal bone computed tomography measurements are useful in predicting round window niche visualisation as viewed endoscopically during posterior tympanotomy. The angle was more acute in type IIb compared to type I.

Preservation of cochlear structures and hearing when using the Nucleus Slim Straight (CI422) electrode in children

2016 ◽  
Vol 130 (4) ◽  
pp. 332-339 ◽  
Author(s):  
H Skarzynski ◽  
M Matusiak ◽  
A Lorens ◽  
M Furmanek ◽  
A Pilka ◽  
...  
Keyword(s):  
Standard Deviation ◽  
Round Window ◽  
Pure Tone Audiometry ◽  
Hearing Preservation ◽  
Electrode Placement ◽  
Insertion Depth ◽  
Electrode Insertion ◽  
Window Approach ◽  
Selection Of ◽  
Categorical Scale

AbstractObjective:In cochlear implantation, there are two crucial factors promoting hearing preservation: an atraumatic surgical approach and selection of an electrode that does not damage cochlear structures. This study aimed to evaluate hearing preservation in children implanted with the Nucleus Slim Straight (CI422) electrode.Methods:Nineteen children aged 6–18 years, with partial deafness, were implanted using the 6-step Skarzynski procedure. Electrode insertion depth was 20–25 mm. Hearing status was assessed with pure tone audiometry before surgery, and at 1, 5, 9, 12 and 24 months after surgery. Electrode placement was confirmed with computed tomography.Results:Mean hearing preservation in the study group at activation of the cochlear implant was 73 per cent (standard deviation = 37 per cent). After 24 months, it was 67 per cent (standard deviation = 45 per cent). On a categorical scale, hearing preservation was possible in 100 per cent of cases.Conclusion:Hearing preservation in children implanted with the Nucleus CI422 slim, straight electrode is possible even with 25 mm insertion depth, although the recommended insertion depth is 20 mm. A round window approach using a soft, straight electrode is most conducive to hearing preservation.

Three-Dimensional Computer Reconstruction of a Temporal Bone

1989 ◽  
Vol 101 (5) ◽  
pp. 522-526 ◽  
Author(s):  
Charles Lutz ◽  
Akira Takagi ◽  
Ivo P. Janecka ◽  
Isamu Sando
Keyword(s):  
Temporal Bone ◽  
Internal Carotid ◽  
Computer Graphic ◽  
Three Dimensional ◽  
Computer Assisted ◽  
Computer Reconstruction ◽  
Temporal Bone Anatomy ◽  
Bone Structures ◽  
Graphic Software ◽  
Computer Graphics System

The complexities of the temporal bone and the critical inter-relationships among its key structures can be simplified with three-dimensional computer-assisted reconstruction. Knowledge of the topography of these structures and their mutual relationships in essential in any surgical approach to the temporal bone. Sixty sagittal histologic sections of a normal left temporal bone were examined. Each section, 30 μm in thickness, was optically enlarged. Segments representing the facial nerve, internal carotid artery, and inner ear structures from individual slides were traced and data were entered into a computer. A personal computer was used for data processing and analysis. Graphic software developed in our laboratory generated images with x-y-z coordinates that could be rotated In any plane. The high resolution of the computer graphics system, combined with the precision of histologic sections, permitted study of the critical three-dimensional anatomic relationships among essential intratemporal bone structures. The capability of reproducing individual and joint images of the intratemporal bone structures and viewing them from all surgical angles gives skull base and otologic surgeons Important topographic guidance. Accurate spatial measurements of temporal bone anatomy are now possible with the application of computer graphic technology.

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 Analysis of tympanic sinus shape for purposes of intraoperative hearing monitoring: a microCT study

2021 ◽  
Author(s):  
Małgorzata Bilińska ◽  
Tomasz Wojciechowski ◽  
Jacek Sokołowski ◽  
Kazimierz Niemczyk
Keyword(s):  
Computed Tomography ◽  
Round Window ◽  
Optimal Placement ◽  
Facial Canal ◽  
Average Width ◽  
Sinus Tympani ◽  
Stapedius Muscle ◽  
Electrode Shape ◽  
Posterior Tympanotomy ◽  
Temporal Bones

Abstract Purpose Sinus tympani is the space in the retrotympanum, with variable morphology. Computed tomography is a common tool to investigate sinus tympani anatomy. During cochlear implantation or tympanoplasty, electrocochleography can be used for hearing monitoring. In such a surgical strategy the electrode is placed in the round window’s region throughout posterior tympanotomy. Common accessible needle-shaped electrodes using is difficult in achieving intraoperative stabilization. The aim of the study is to assess the dimensions and shape of sinus tympani, basing on the micro computed tomography scans for purposes of establishing the possible new electrocochleography electrode shape. Materials and methods Sixteen fresh frozen cadaveric temporal bones were dissected. MicroCT measurements included the depth and the width of sinus tympani, width of facial canal with stapedius muscle chamber. Obtained data were analyzed statistically with the use of RStudio 1.3.959 software. Results The highest average width of sinus tympani amounted for 2.68 mm, depth measured at the round window plane for 3.19 mm. Width of facial canal with stapedius muscle chamber highest average values at the round window plane- 3.32 mm. The lowest average minimum and maximum values were calculated at the 1 mm above the round window plane. The highest average posterior tympanotomy width was 2.91 mm. Conclusions The shape of the tympanic sinus is like a trough with the narrowest and deepest dimensions in the middle part. The ST shape and dimensions should be taken into account in constructing the ECochG electrode, designed for optimal placement through posterior tympanotomy approach.

scholarly journals Herniation of the Mastoid Segment of the Facial Nerve During Cochlear Implantation Surgery

2021 ◽  
pp. 014556132110516
Author(s):  
Mohammad Almohammad ◽  
Tala Tasabehji ◽  
Abdulrahman Awad ◽  
Ibrahem Hanafi
Keyword(s):  
Facial Nerve ◽  
Hearing Aids ◽  
Cochlear Implantation ◽  
Round Window ◽  
Posterior Wall ◽  
Case Presentation ◽  
Posterior Tympanotomy ◽  
Bilateral Sensorineural Hearing Loss ◽  
The Right ◽  
Electrical Stimuli

Background: We aim to report a rare case of a herniated mastoid segment of the facial nerve that was accidently discovered during cochlear implantation surgery and how altering the surgery plan could achieve the implantation while preserving the nerve. Case presentation: A four-year-old girl presented with profound bilateral sensorineural hearing loss that did not completely resolve after 2 years of using hearing aids was scheduled for cochlear implantation surgery in the right ear. During surgery, a herniated mastoid segment of the facial nerve took an anterior course and obstructed the access to the round window. Conclusion: When a traditional posterior tympanotomy approach in cochlear implantation surgery is limited in cases of a herniated facial nerve, a tunnel created near the inferior part of the posterior wall of the auditory canal provided safe insertion of the electrode. It also permitted placement of a piece of fascia between the electrode and the facial nerve, therefore, protecting the facial nerve from electrical stimuli.

scholarly journals Vestibular Preservation After Cochlear Implantation Using the Round Window Approach

2021 ◽  
Vol 12 ◽  
Author(s):  
Keita Tsukada ◽  
Shin-ichi Usami
Keyword(s):  
Cochlear Implantation ◽  
Round Window ◽  
Surgical Techniques ◽  
Vestibular Function ◽  
Vestibular Evoked Myogenic Potential ◽  
Flexible Electrodes ◽  
Caloric Testing ◽  
Before And After ◽  
Window Approach ◽  
Caloric Response

Background: The development of less traumatic surgical techniques, such as the round window approach (RWA), as well as the use of flexible electrodes and post-operative steroid administration have enabled the preservation of residual hearing after cochlear implantation (CI) surgery. However, consideration must still be given to the complications that can accompany CI. One such potential complication is the impairment of vestibular function with resulting vertigo symptoms. The aim of our current study was to examine the changes in vestibular function after implantation in patients who received CI using less traumatic surgery, particularly the RWA technique.Methods: Sixty-six patients who received CI in our center were examined by caloric testing, cervical vestibular evoked myogenic potential (cVEMP) and ocular VEMP (oVEMP) before or after implantation, or both, to obtain data on semicircular canal, saccular and utricular function, respectively. Less traumatic CI surgery was performed by the use of the RWA and insertion of flexible electrodes such as MED-EL FLEX soft, FLEX 28, and FLEX 24 (Innsbruck, Austria).Results: Caloric response and the asymmetry ratio of cVEMP and oVEMP were examined before and after implantation using less traumatic surgical techniques. Compared with before implantation, 93.9, 82.4, and 92.5% of the patients showed preserved vestibular function after implantation based on caloric testing, cVEMP and oVEMP results, respectively. We also examined the results for vestibular function by a comparison of the 66 patients using the RWA and flexible electrodes, and 17 patients who underwent cochleostomy and insertion of conventional or hard electrodes. We measured responses using caloric testing, cVEMP and oVEMP in patients after CI. There were no differences in the frequencies of abnormal caloric and oVEMP results in the implanted ears between the RWA and cochleostomy. On the other hand, the frequency of abnormal cVEMP responses in the implanted ears in the patients who received implantation by cochleostomy was significantly higher than that in the patients undergoing surgery using the RWA.Conclusion: Patients receiving CI using less traumatic surgical techniques such as RWA and flexible electrodes have reduced risk of damage to vestibular function.

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