Cochleostomy Approach Research Articles

Dependability of Electrode to Modiolus Distance in Patients Specific Electrode Selection: A Cadaveric Model Study.

This study aims to discern the disparities in the electrode-to-modiolus distance (EMD) between cochleostomy and round window approaches when performed sequentially in the same temporal bone. Additionally, the study seeks to identify the cochlear metrics that contribute to these differences. A cross-sectional study was conducted, involving the sequential insertion of a 12-electrode array through both round window and cochleostomy approaches in cadaveric temporal bones. Postimplantation high-resolution CT scans were employed to calculate various parameters. A total of 12 temporal bones were included in the imaging analysis, revealing a mean cochlear duct length of 32.892 mm. The EMD demonstrated a gradual increase from electrode 1 (C1) in the apex (1.9 ± 0.07 mm; n = 24) to electrode 12 (C12) in the basal turn (4.6 ± 0.24 mm; n = 12; p < 0.01). Significantly higher EMD values were observed in the cochleostomy group. Correlation analysis indicated a strong positive correlation between EMD and cochlear perimeter (CP) (rs = 0.64; n = 12; p = 0.03) and a strong negative correlation with the depth of insertion (DOI) in both the middle and basal turns (rs = - 0.78; n = 20; p < 0.01). Additionally, EMD showed a strong negative correlation with the DOI-CP ratio (rs = -0.81; n = 12; p < 0.01). The cochleostomy group exhibited a significantly higher EMD compared with the round window group. The strong negative correlation between EMD and DOI-CP ratio suggests that in larger cochleae with shallower insertions, EMD is greater than in smaller cochleae with deeper insertions. NA Laryngoscope, 134:4736-4744, 2024.

Comparison of depth of electrode insertion between cochleostomy and round window approach: a cadaveric study.

Round window approach and cochleostomy approach can have different depth of electrode insertion during cochlear implantation which itself can alter the audiological outcomes in cochlear implant. The current study was conducted to determine the difference in the depth of electrode insertion via cochleostomy and round widow approach when done serially in same temporal bone. This is a cross-sectional study conducted in the Department of Otorhinolaryngology in conjunction with Department of Anatomy and Department of Diagnostic and Interventional Radiology over a period of 1year. 12-electrode array insertion was performed via either approach (cochleostomy or round window) in the cadaveric temporal bone. HRCT temporal bone scan of the implanted temporal bone was done and depth of insertion and various cochlear parameters were calculated. A total of 12 temporal bones were included for imaging analysis. The mean cochlear duct length was 32.892mm; the alpha and beta angles were 58.175° and 8.350°, respectively. The mean angular depth of electrode insertion via round window was found to be 325.2° (SD = 150.5842) and via cochleostomy 327.350 (SD = 112.79) degree and the mean linear depth of electrode insertion via round window was found to be 18.80 (SD = 4.4962) mm via cochleostomy 19.650 (SD = 3.8087) mm, which was calculated using OTOPLAN 1.5.0 software. There was a statically significant difference in linear depth of insertion between round window and cochleostomy. Although the angular depth of insertion was higher in CS group, there was no statistically significant difference with round window type of insertion. The depth of electrode insertion is one of the parameters that influences the hearing outcome. Linear depth of electrode insertion was found to be more in case of cochleostomy compared to round window approach (p = 0.075) and difference in case of angular depth of electrode insertion existed but not significant (p = 0.529).

The effect of cochlear implant insertion technique on post-operative neural response telemetry and impedance in paediatric patients.

This study aimed to compare neural response telemetry and impedance between the round window and cochleostomy approaches for cochlear implantation. In this case-control study, 64 patients aged less than 3.5 years underwent cochlear implantation via the round window or cochleostomy approach. Post-operative neural response telemetry and impedance were measured. The impedance measurements at electrodes 1, 11 and 22 showed no significant differences between the two groups three months after implantation (p = 0.90, p = 0.08 and p = 0.37, respectively). Similar results were observed six months after implantation (p = 0.71, p = 0.65 and p = 0.70, respectively). There was no significant difference in neural response telemetry between the two groups after three months. The neural response telemetry of electrode 1 in the cochleostomy group (171.26 ± 19.81 μV) was significantly higher in comparison with that of electrode 1 in the round window group (161.97 ± 12.71 μV) after six months (p = 0.03). The neural response telemetry values for electrodes 11 and 22 did not show any significant difference after six months (p = 0.14 and p = 0.48, respectively). Both approaches provide equal stimulation of the cochlear nerve and impedance.

Ultra-High-Resolution CT to Detect Intracochlear New Bone Formation after Cochlear Implantation.

Background Histopathologic studies reported that cochlear implantation, a well-established means to treat severe-to-profound sensorineural hearing loss, may induce inflammation, fibrosis, and new bone formation (NBF) with possible impact on loss of residual hearing and hearing outcome. Purpose To assess NBF in vivo after cochlear implantation with ultra-high-spatial-resolution (UHSR) CT and its implication on long-term residual hearing outcome. Materials and Methods In a secondary analysis of a prospective single-center cross-sectional study, conducted between December 2016 and January 2018, patients with at least 1 year of cochlear implantation experience underwent temporal bone UHSR CT and residual hearing assessment. Two observers evaluated the presence and location of NBF independently, and tetrachoric correlations were used to assess interobserver reliability. In addition, the scalar location of each electrode was assessed. After consensus agreement, participants were classified into two groups: those with NBF (n = 83) and those without NBF (n = 40). The association between NBF and clinical parameters, including electrode design, surgical approach, and long-term residual hearing loss, was tested using the χ2 and Student t tests. Results A total of 123 participants (mean age ± standard deviation, 63 years ± 13; 63 women) were enrolled. NBF was found in 83 of the 123 participants (68%) at 466 of 2706 electrode contacts (17%). Most NBFs (428 of 466, 92%) were found around the 10 most basal contacts, with an interobserver agreement of 86% (2297 of 2683 contacts). Associations between electrode types and surgical approaches were significant (58 of 79 participants with NBF and a precurved electrode vs 24 of 43 with NBF and a straight electrode, P = .04; 64 of 88 participants with NBF and a cochleostomy approach vs 18 of 34 with NBF and a round window approach, P = .03). NBF was least often seen in full scala tympani insertions, but there was no significant association between scalar position and NBF (P = .15). Long-term residual hearing loss was significantly larger in the group with NBF compared with the group without NBF (mean, 22.9 dB ± 14 vs 8.6 dB ± 18, respectively; P = .04). Conclusion In vivo detection of new bone formation (NBF) after cochlear implantation is possible by using ultra-high-spatial-resolution CT. Most cochlear implant recipients develop NBF, predominately located at the base of the cochlea. NBF adversely affects long-term residual hearing preservation. © RSNA, 2021 An earlier incorrect version appeared online. This article was corrected on December 8, 2021.

Histopathologic Analysis of Temporal Bones With Otosclerosis Following Cochlear Implantation.

Analyze changes in osteoneogenesis and fibrosis following cochlear implant (CI) surgery in patients with otosclerosis and compare differences based on insertion technique. When advanced otosclerotic disease extends to the otic capsule, severe and profound sensorineural hearing loss necessitates consideration of a cochlear implant. Histopathological analysis of the human temporal bone after implantation in the patient with otosclerosis may reveal important variables that predict CI success. Histopathological evaluation of archival human temporal bones from subjects with a history of CI for cochlear otosclerosis. A total of 17 human temporal bones (HTB) were analyzed, 13 implanted, and 4 contralateral non-implanted controls. Histopathological studies revealed extensive osteoneogenesis and fibrosis which was more prominent at the cochleostomy insertion site in the basal turn of the cochlea often obliterating the scala tympani in the basal turn, and in some cases extending to the scala media and scala vestibuli. Cochlear hydrops was nearly universal in these cases. This contrasted with the round window insertion, which exhibited minimal osteoneogenesis within the cochlear duct. In addition, in the contralateral, unimplanted control ears, there was otosclerosis at the stapes footplate, fissula ante fenestrum but no osteoneogenesis within the cochlear duct. Cochleostomy approach to CI insertion in otosclerosis patients is associated with significant fibrosis, osteoneogenesis, and cochlear hydrops. A round window insertion technique can be utilized to help minimize these histopathologic findings whenever feasible.

Surgical management of cochlear implant in chronic otitis media patients: safe and sound

Introduction Cochlear implantation (CI) in cases with chronic otitis media (COM) was previously contraindicated but recent advances have made it possible. Objective To review surgical and audiological outcomes of COM patients that underwent CI. Material and methods Retrospective review of patients above 18 years old. Results Ten patients with complete data were included. Patients were aged 24–69 years old. Tympanoplasty and mastoidectomy were performed before CI. Imaging was performed to rule out ossifications. Eight patients underwent a standard canal wall up with either cochleostomy or round window approach. One patient had additional canalplasty and tympanoplasty and another one had blind sac procedure respectively. Analysis of the hearing aided level with CI and hearing aid showed significant benefit provided by the CI (Z = 2.803, p = .005). Discussion Creating a dry and safe ear is important prior to CI. Definite hearing improvement is seen in all our cases that helped them to become independent again in their daily life. Hearing aid usage pre-CI might not be important as the hearing aids may continue to cause discharging ears and the benefits of hearing aids in severe to profound hearing loss are very minimal. Conclusions Cochlear implant is safe and effective in COM patients.

Which approach is better for the protection of vestibular receptors in cochlear implant surgery: Round window or standard cochleostomy?

Objectives: This study aims to compare electrode insertion techniques in cochlear implantation (CI) as the standard cochleostomy approach (SCA) versus the round window approach (RWA) on five vestibular end-organ functions and vertigo in the pre- and postoperative period. Patients and Methods: In total, 51 patients (22 males, 29 females; mean age 38.2 years; range 16 to 70 years) with normal vestibular function and operated with single-sided CI were included in this study between January 2015 and December 2019. Of the patients, 30 were operated with the RWA and 21 with the SCA. All of the patients were evaluated with the Dizziness Handicap Inventory (DHI) and a complete vestibular test battery including the video head impulse test (vHIT), cervical vestibular-evoked myogenic potential (cVEMP), and ocular vestibular-evoked myogenic potential (oVEMP) at one week preoperatively and one month postoperatively. Results: Patients in the RWA group had a statistically significantly better protected vestibular functions and fewer subjective vertigo symptoms in the postoperative period (p&lt;0.05). Deterioration in at least one of the five vestibular end-organ functions was observed in eight of 21 patients (38.09%) in the SCA group, compared to three of 30 (10%) in the RWA group. A significant correlation was detected between the vestibular tests and DHI in both groups (r=0.686, p=0.001 in the SCA group and r=0.630, p&lt;0.001 in the RWA group). Conclusion: Our study results suggest that RWA for CI may minimize damage to vestibular receptor functions and vertigo symptoms than SCA.

Comparison of the Pediatric Cochlear Implantation Using Round Window and Cochleostomy.

Introduction:Cochlear implantation (CI) is now regarded as a standard treatment for children with severe to profound sensor neural hearing loss. This study aimed to compare the efficacy of the round window approach (RWA) and standard cochleostomy approach (SCA) in the preservation of residual hearing after CI in pediatric patients.Materials and Methods:This double-blind randomized controlled trial was conducted on 97 pediatric patients receiving CI with 12-month follow-up. The study population was divided into two groups according to the surgical approaches they received, including RWA and SCA. Consequently, the patients were evaluated based on the Categories of Auditory Performance scale (CAP) and Speech Intelligibility Rating (SIR) test 45-60 days and 3, 6, 9, and 12 months post-surgery.Results:The CAP and SIR mean scores increased in both groups during the 12-month follow-up. This upward trend was significant in both groups (P<0.001). There was no significant difference between the two treatment groups in any of the follow-up stages regarding the CAP mean score. The mean SIR score (P=1.14±0.40) was significantly higher in the RWA group 3(P=0.001), 6(P=0.008), and 9(P=0.006) months after the surgery. However, there was no significant difference between the RWA and SCA groups, regarding 1-year SIR (P=0.258).Conclusion:The CI with either RWA or SCA could improve hearing and speech performance in pediatric patients. Although mid-term speech intelligibility was better for RWA, there was no significant difference in the 1-year outcome between these two methods.

The evaluation of a slim perimodiolar electrode: surgical technique in relation to intracochlear position and cochlear implant outcomes

PurposeIn cochlear implantation (CI), the two factors that are determined by the surgeon with a potential significant impact on the position of the electrode within the cochlea and the potential outcome, are the surgical technique and electrode type. The objective of this prospective study was to evaluate the position of the slim, perimodiolar electrode (SPE), and to study the influence of the SPE position on CI outcome.MethodsTwenty-three consecutively implanted, adult SPE candidates were included in this prospective cohort study conducted between December 2016 and April 2019. Mean age at surgery was 59.5 years. Mean preoperative residual hearing was 92.2 dB. Intra-operative fluoroscopy and high-resolution computed tomography scans were performed to evaluate electrode position after insertion using a cochleostomy (CS) approach. Follow-up was 12 months after implantation; residual hearing (6–8 weeks) and speech perception (6–8 weeks and 12 months) were evaluated in relation to the intracochlear SPE position.ResultsIn most patients in whom the SPE was positioned in the scala tympani residual hearing was preserved [mean absolute increase in PTA of 4.4 dB and 77.2% relative hearing preservation (RHP%)]. Translocation into the scala vestibuli occurred in 36% of the insertions, resulting in a mean absolute increase in PTA of 17.9 dB, and a RHP% of 19.2%. Participants with a translocation had poorer speech perception scores at 12-month follow-up.ConclusionGiven the incidence of CS-associated translocations with the SPE and the negative effect on outcome, it is advised to insert the SPE using the (extended) round window approach.

Temporal Bone Histopathology of First-Generation Cochlear Implant Electrode Translocation.

To evaluate the histopathology of human temporal bones (HTBs) with cochlear implants (CI). Understanding CI translocation injuries is critical for improving outcomes. Thirteen HTBs from 12 CI patients were studied. Six HTBs exhibited translocation with localized injury (Group 1) and seven HTBs exhibited translocation with significant lateral wall injury (Group 2). There were no significant differences between Group 1 and Group 2 for age at death, age at implantation, and years with CI. Four out of six of Group 1 had round window approach, while all seven of Group 2 had cochleostomy approach. Translocation injuries tended to occur near 180 degrees of angular insertion with a mean of 186.36 ± 51.62 degrees. Average CI insertion length for Group 2 was 21.86 ± 2.55 mm, significantly longer than Group 1 at 18.50 ± 3.33 mm (p = 0.031). Group 1 had an average of 17300 ± 9415 spiral ganglia neurons (SGNs) while Group 2 had significantly fewer SGNs 6714 ± 4269 (p = 0.015). Group 1 average auditory performance of 66.55 ± 27.20% was higher than that of Group 2 of 39.86 ± 15.36%. Group 2 had a high degree of osteoneogenesis and infiltration of cells generally localized to areas of translocation injury and cochleostomy. Translocation injuries tend to occur at an insertion angle of 180 degrees, at 9 to 10 mm. Lateral wall injury and damage to the organ of Corti incites fibrosis, osteoneogenesis, and infiltration, lower SGN count and poorer auditory performance. Longer electrodes were more prone to translocation and higher chance of significant intracochlear injury.

A New Lateral Wall Electrode: Evaluation of Surgical Handling, Radiographic Placement, and Histological Appraisal of Insertion Trauma.

To describe histologic and radiographic findings associated with insertion of a new lateral wall electrode in human temporal bones, as well as quantify the ease of insertion as characterized by multiple cochlear implant surgeons. Multi-institutional cadaveric study. The Slim J electrode was inserted in cadaveric temporal bones via a standard mastoidectomy and facial recess approach. Insertion was performed by five cochlear implant surgeons with no previous experience with the Slim J electrode array. Electrode array insertion was performed via a round window, an extended round window, or a cochleostomy approach. Intracochlear trauma, and angular insertion depth was assessed histologically and radiologically, respectively, after placement of the Slim J electrode array. Scala tympani insertion was accomplished in all 40 specimens. Thirty-eight specimens (95%) showed minimal trauma (Esrhaghi grade 0 or 1). One patient had rupture of basilar membrane (grade 2 trauma) at 380 degrees. One patient had grade 4 trauma with scalar translocation beginning at 210 degrees. The mean angular insertion depth was 416.4 degrees (range: 338.7-509.2 degrees, SD 44 degrees). Surgical handling was described as easy in 38 cases (95%). In a human cadaveric model the lateral wall Slim J electrode produced minimal intracochlear trauma that was positioned completely within the scala tympani in 97.5% of cases.

Lower initial electrode impedances in minimally invasive cochlear implantation

Background: The round window approach and the cochleostomy approach are two widely practiced methods to insert cochlear implant electrode arrays. Yet, there is no consensus on which is more minimally invasive. Objective: To compare the initial electrode impedance (EI) values and the incidence of abnormal electrodes of the round window approach and the cochleostomy approach, and to evaluate the effects of surgical techniques on the intracochlear microenvironment. Material and methods: One hundred and seventy-one patients received a unilateral Nucleus cochlear implant. Eighty-two patients were implanted using the round window approach, and 89 patients were implanted using the cochleostomy approach. EI was measured immediately after closure of the incision. Results: The round window group had lower average initial EI values than the cochleostomy group. For the EI values at each position, statistically significant differences were found in the basal-middle region (Electrode 1–14), but not in the middle-apical region (Electrode 15–22) of the electrode arrays. A lower incidence of high-impedance electrodes was found in the round window group. Conclusions: The round window approach leads to lower initial EI and less disturbance to the intracochlear microenvironment.

Hearing Preservation in Cochlear Implant Surgery: A Meta-Analysis.

The aim of the present meta-analysis is to assess the effects of hearing preservation (HP) methods on residual hearing in patients undergoing cochlear implant (CI) surgery and to look at the effect of follow-up time on HP outcome. A systematic search was conducted in PubMed, Embase, and Cochrane Library. Only articles in English were included. Prospective studies published until January 2018 on hearing preservation methods were included. Studies were assessed on unaided pre- and postoperative hearing thresholds, follow up time, and methodological quality. A random-effects meta-regression was performed for the HP outcome in relation to surgical technique, electrode array design, inserted electrode length, insertion speed, and corticosteroid use for different follow up times (1 month, 6 months, and 12 months or more postoperatively). Hearing preservation in cochlear implant surgery is feasible. A statistically significant difference was found between the round window procedure and cochleostomy approach, in favor of the round window procedure at 6 months postoperatively (p = 0.001). A statistically significant difference was found between the straight and the perimodiolar electrode array at 1 month postoperatively in favor of the straight electrode array (p < 0.001). No statistically significant difference was found between the other HP methods. The round window approach with the straight electrode array might result in a better HP outcome at 1 month and 6 months postoperatively compared with the cochleostomy approach with the perimodiolar electrode array. A declining trend in HP outcome in both combinations was seen over time.

Effects of Various Trajectories on Tissue Preservation in Cochlear Implant Surgery: A Micro-Computed Tomography and Synchrotron Radiation Phase-Contrast Imaging Study.

The purpose of this study was to evaluate the three-dimensional (3D) anatomy and potential damage to the hook region of the human cochlea following various trajectories at cochlear implantation (CI). The goal was to determine which of the approaches can avoid lesions to the soft tissues, including the basilar membrane and its suspension to the lateral wall. Currently, there is increased emphasis on conservation of inner ear structures, even in nonhearing preservation CI surgery. Micro-computed tomography and various CI approaches were made in an archival collection of macerated and freshly fixed human temporal bones. Furthermore, synchrotron radiation phase-contrast imaging was used to reproduce the soft tissues. The 3D anatomy was investigated using bony and soft tissue algorithms, and influences on inner ear structures were examined. Micro-computed tomography with 3D rendering demonstrated the topography of the round window (RW) and osseous spiral laminae, while synchrotron imaging allowed reproduction of soft tissues such as the basilar membrane and its suspension around the RW membrane. Anterior cochleostomies and anteroinferior cochleostomies invariably damaged the intracochlear soft tissues while inferior cochleostomies sporadically left inner ear structures unaffected. Results suggest that cochleostomy approaches often traumatize the soft tissues at the hook region at CI surgery. For optimal structural preservation, the RW approach is, therefore, recommended.

Comparison of electrode position between round window and cochleostomy inserting approaches among young children: a cone-beam computed tomography study

Background: As the two most commonly used approaches for cochlear implants (CIs), the round-window insertion (RWI) and cochleostomy are still controversial about which approach is optimal. The lack of visual observation methods makes it difficult to compare the electrode position between them.Objectives: To evaluate and compare the electrode position between RWI and cochleostomy approaches for CI among young children.Materials and methods: Twenty-four patients (16 male, 8 female) accepting CI and temporal cone-beam computed tomography (CBCT) scan post-operation in our hospital from January 2016 to July 2017 were analyzed retrospectively. Operative notes and images were used to identify the surgical technique. Mainly depending on the round-window exposure, 15 cochleae were performed with RWI and 11 performed with cochleostomy.Results: Mean age, 2.4 (range 0.8–7) years. The CBCT images showed that all the electrode arrays were located in scala tympani. There were no significantly statistical differences in the distance between electrode contacts and modiolus (EMI), intracochlear insertion length and the angle of electrode arrays at the insertion site of the cochlea.Conclusions and significance: Both approaches could insert electrodes into scala tympani satisfactorily. As electrodes and cochlear structures could be clearly visualized, CBCT can be applied to assess the electrode position reliably.

Preservation of residual hearing after cochlear implant surgery: an exploration of residual hearing function in a group of recipients at cochlear implant units

IntroductionThe preservation of residual hearing is becoming increasingly important in cochlear implant surgery. Conserving residual hearing is a positive prognostic indicator for improved hearing abilities. ObjectiveThe primary aim of the study was to explore the preservation of residual hearing following cochlear implantation in a group of recipients at two major cochlear implant centers. MethodsA quantitative paradigm was adopted and exploratory research conducted within a retrospective data review design. The sample consisted of 50 surgical records and 53 audiological records from 60 observations (53 patients, seven of whom were implanted bilaterally). The records were selected using purposive sampling and consisted of records from participants ranging from six to 59 years of age. The average time of when the postoperative audiograms were performed in the current study was 24.7 months (s.d.=±9.0). Data were analyzed through both qualitative and inferential statistics and a comparative analysis of unaided pre- and postoperative audiological test results was conducted. ResultsResults indicated a high success rate of 92% preservation of residual hearing with half of the sample exhibiting complete preservation in cochlear implant recipients across all frequencies postoperatively. A total postoperative hearing loss was found in only 8% of cochlear implantees across all frequencies. There was no relationship between preoperative hearing thresholds and preservation of hearing postoperatively. The two main surgical techniques used in the current study were the contour on stylet and the advance off-stylet techniques, with the majority of surgeons utilizing a cochleostomy approach. From the findings, it became apparent that the majority of cases did not have any reported intraoperative complications. This is a positive prognostic indicator for the preservation of residual hearing. ConclusionFindings suggest improved cochlear implant surgical outcomes when compared to previous studies implying progress in surgical techniques. The surgical skill and experience of the surgeon are evidenced by the minimal intraoperative complications and the high success rate of hearing preservation. This is a positive prognostic indicator for individuals with preoperative residual hearing as the preserved residual hearing allows for the potential of electro-acoustic stimulation, which in turn has its own hearing benefits.

Vestibular Outcome After Cochlear Implantation Is Not Related to Surgical Technique: A Double Blinded, Randomized Clinical Trial of Round Window Approach Versus Cochleostomy.

Objective:To establish whether the round window approach (RWA) leads to less vestibular dysfunction and dizziness than the standard cochleostomy approach (SCA) during cochlear implant (CI) surgery, as assessed using the video head impulse test (vHIT).Additionally, objective findings were compared with the subjective dizziness perceived by the patient.Study Design:Double blinded, clinical randomized trial.Setting:University Hospital.Patients:Fifty-two ears from 46 patients were included. Inclusion criterion was a gain value more than 0.50.Intervention:Patients were randomized to the RWA or the SCA. Evaluation with the vHIT was performed before surgery, 1 day after surgery, and 1 month after surgery. Subjective dizziness was measured using a visual analogue scale (VAS) and the dizziness handicap inventory (DHI).Main Outcome Measures:Gain values and the incidence of catch-up saccades.Results:Three out of 23 patients in the SCA group experienced catch-up saccades compared with no patients in the RWA group, indicating the occurrence of objective vestibular dysfunction after CI surgery; the difference was not statistically significant. The VAS increased in both groups the day after surgery. The difference between the groups was not statistically significant. No statistically significant changes in the gain value or the DHI score could were observed between the two groups.Conclusion:No statistically significant difference between the cochleostomy approach and the round window approach using the vHIT and subjective dizziness perceived by the patient was found.

Survey of the American Neurotology Society on Cochlear Implantation: Part 2, Surgical and Device-Related Practice Patterns.

To examine surgical and device-related cochlear implant practice patterns across centers in the United States. Cross-sectional survey of the American Neurotology Society (ANS). A total of 81 surveys were returned from ANS members who report regular involvement in cochlear implant care. Overall there was a broad distribution in age and clinical experience, with most respondents reporting Accreditation Council for Graduate Medical Education (ACGME) accreditation in neurotology and employment at an academic center. The annual volume of cochlear implant surgeries varied considerably across centers. Eighty percent of respondents report to offer all three Food and Drug Administration (FDA) approved device brands at their center.In cases where hearing preservation is not a goal, 56% of respondents prefer a perimodiolar electrode design, while 44% prefer a lateral wall electrode. With regard to insertion technique for scala tympani access, 64% prefer inserting through the round window (RW) membrane, 26% prefer an extended round window (ERW) approach, while only 10% prefer a cochleostomy. In cases where hearing preservation is a goal of surgery, 86% of respondents prefer a lateral wall electrode design, while only 14% prefer a perimodiolar electrode design. With regard to insertion technique, 86% prefer RW insertion, while only 9% prefer an ERW approach, and only 5% prefer a cochleostomy. Respondents who prefer RW electrode insertion more commonly use a lateral wall electrode, whereas those who prefer an ERW or cochleostomy approach more commonly use a periomodiolar electrode (p < 0.001). There was a statistically significant greater number of surgeons that prefer lateral wall electrodes (p < 0.001) and RW insertion (p < 0.001) for hearing preservation cases compared with non-hearing preservation cases. For implantation of a hypothetical patient with significant residual hearing, within the range of hybrid device candidacy, the great majority of surgeons prefer a conventional length electrode and only 29% prefer to implant a hybrid device.In cases where hearing preservation is a goal, the overwhelming majority of respondents (96%, n = 74) reported using at least one form of steroid application. Ninety-two percent (n = 71) used intraoperative intravenous steroids, 55% (n = 42) prescribed postoperative oral steroids, 44% (n = 34) bathed the middle ear with steroids during surgery, and 30% (n = 23) prescribed preoperative oral steroids.Together, 65% of respondents use a variation of the tight subperiosteal pocket technique for internal device fixation, 19% prefer a bony well and trough with tie-downs, 10% prefer a bony well and trough without tie-downs, and 5% prefer a screw fixation system. Of the 50 who prefer utilizing a subperiosteal pocket, 31 (62%) incorporate a bony trough and 19 (38%) perform a subperiosteal pocket alone without a bony trough. The results of this survey reflect the evolution in surgical and device-related preferences for cochlear implantation in the United States. An increasing number of surgeons prefer the RW approach for electrode insertion. When hearing preservation is not a goal, there is a near even preference for lateral wall and perimodiolar electrode designs; however, the great majority of surgeons prefer a lateral wall design when attempting to preserve residual acoustic hearing. Even in cases where substantial residual hearing exists, many surgeons prefer conventional length electrodes to hybrid designs. These changes reflect the prioritization of atraumatic surgery and parallel the development of thinner and more atraumatic electrodes.

The influence of cochlear morphology on the final electrode array position.

Preoperative information about cochlear morphology and size increasingly seems to be a defining factor of electrode choice in cochlear implant surgery. Different types of electrodes differ in length and diameter to accommodate individual cochlear anatomy. Smaller cochlear size results in increased insertion depth with a higher risk to dislocate and causes cochlear trauma with reduced postoperative outcome. The objective of the current study is to describe the three-dimensional size of the cochlea, to compare interindividual differences, to determine the relationship between cochlear size and insertion angle, and to define risk factors for dislocation during insertion. Four hundred and three patients implanted between 2003 and 2010 inserted via cochleostomy with a perimodiolar electrode array (Cochlear™ Contour Advance® electrode array) have been compared. CBCT (Cone beam computed tomography) was used to determine electrode array position (scala tympani versus scala vestibuli insertion, intracochlear dislocation, and insertion angle) and cochlear size (diameters and height). The trajectory of the electrode array and the lateral wall have been measured, and the position of the electrode array has been estimated. The mean value of the largest diameter was 9.95mm and that of the perpendicular distance was 6.54mm. There was a statistically significant correlation between those values. Mean height was 3.85mm. The intracochlear relation of the electrode array and the modiolus showed a statistically significant relationship with the cochlear expanse. The electrode array was more likely to dislocate in cochleae with a smaller diameter and a lower height. Cochleae with insertions into scala vestibuli exhibited a smaller height compared to scala tympani insertions with statistical significance. Cochlear size and shape is variable, and the measured data of this study confirm the finding of other researchers. This study established two heights by two different planes to achieve a three-dimensional understanding of the cochlea. The electrode array was more likely to dislocate in cochleae with smaller diameter and smaller height. It can be assumed that the height established in this study seems to be a new preoperative parameter to underline the risk of scalar dislocation and not favored scala vestibuli insertion if using a cochleostomy approach. In conclusion, cochlear size, especially the height, is influencing the final position of the electrode array. Using preoperative scans of the cochlear diameters and cochlear height, a next step to custom-sized arrays is available.

Clinical investigation of the Nucleus Slim Modiolar Electrode

Aims: The Nucleus CI532 cochlear implant incorporates a new precurved electrode array, i.e., the Slim Modiolar electrode (SME), which is designed to bring electrode contacts close to the medial wall of the cochlea while avoiding trauma due to scalar dislocation or contact with the lateral wall during insertion. The primary aim of this prospective study was to determine the final position of the electrode array in clinical cases as evaluated using flat-panel volume computed tomography. Methods: Forty-five adult candidates for unilateral cochlear implantation were recruited from 8 centers. Eleven surgeons attended a temporal bone workshop and received further training with a transparent plastic cochlear model just prior to the first surgery. Feedback on the surgical approach and use of the SME was collected via a questionnaire for each case. Computed tomography of the temporal bone was performed postoperatively using flat-panel digital volume tomography or cone beam systems. The primary measure was the final scalar position of the SME (completely in scala tympani or not). Secondly, medial-lateral position and insertion depth were evaluated. Results: Forty-four subjects received a CI532. The SME was located completely in scala tympani for all subjects. Pure round window (44% of the cases), extended round window (22%), and inferior and/or anterior cochleostomy (34%) approaches were successful across surgeons and cases. The SME was generally positioned close to the modiolus. Overinsertion of the array past the first marker tended to push the basal contacts towards the lateral wall and served only to increase the insertion depth of the first electrode contact without increasing the insertion depth of the most apical electrode. Complications were limited to tip fold-overs encountered in 2 subjects; both were attributed to surgical error, with both reimplanted successfully. Conclusions: The new Nucleus CI532 cochlear implant with SME achieved the design goal of producing little or no trauma as indicated by consistent scala tympani placement. Surgeons should be carefully trained to use the new deployment method such that tip fold-overs and over insertion may be avoided.