scholarly journals Computed-tomography estimates of interaural mismatch in insertion depth and scalar location in bilateral cochlear-implant users

2021 ◽  
Author(s):  
Matthew J Goupell ◽  
Jack H Noble ◽  
Sandeep A Phatak ◽  
Elizabeth Kolberg ◽  
Miranda Cleary ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Cochlear Implant ◽  
Surgical Techniques ◽  
Superior Olivary Complex ◽  
Negative Consequences ◽  
Scala Tympani ◽  
Insertion Depth ◽  
Binaural Processing ◽  
Bilateral Cochlear Implant ◽  
Interaural Differences

Hypothesis: We hypothesized that the bilateral cochlear-implant (BI-CI) users would have a range of interaural insertion-depth mismatch because of different physical placements or characteristics of the arrays, but less than half of electrodes would have less than 75° or 3 mm of interaural insertion-depth mismatch. We also hypothesized that interaural insertion-depth mismatch would be more prevalent nearer the apex, when electrodes were located outside of scala tympani (i.e., possible interaural scalar mismatch), and when the arrays were a mix of pre-curved and straight types. Background: Brainstem neurons in the superior olivary complex are exquisitely sensitive to interaural differences, the cues to sound localization. These binaurally sensitive neurons rely on interaurally place-of-stimulation-matched inputs at the periphery. BI-CI users may have interaural differences in insertion depth and scalar location, causing interaural place-of-stimulation mismatch that impairs binaural abilities. Methods: Insertion depths and scalar locations were calculated from temporal-bone computed-tomography (CT) scans of 107 BI-CI users (27 Advanced Bionics, 62 Cochlear, and 18 Med-El). Each subject had either both pre-curved, both straight, or one of each type of array (mixed). Results: The median interaural insertion-depth mismatch was 23.4° or 1.3 mm. Relatively large interaural insertion-depth mismatch sufficient to disrupt binaural processing occurred for about 15% of electrode pairs [defined as >75° (13.0% of electrode pairs) or >3 mm (19.0% of electrode pairs)]. There was a significant three-way interaction of insertion depth, scalar location, and array type. Interaural insertion-depth mismatch was most prevalent when electrode pairs were more apically located, electrode pairs had interaural scalar mismatch (i.e., one in Scala Tympani, one in Scala Vestibuli), and when the arrays were both pre-curved. Conclusion: Large interaural insertion-depth mismatch can occur in BI-CI users. For new BI-CI users, improved surgical techniques to avoid interaural insertion-depth and scalar mismatch is recommended. For existing BI-CI users with interaural insertion-depth mismatch, interaural alignment of clinical frequency allocation tables by an audiologist might remediate any negative consequences to spatial-hearing abilities.

scholarly journals Clinical investigation of the Nucleus Slim Modiolar Electrode

2017 ◽  
Vol 22 (3) ◽  
pp. 169-179 ◽  
Author(s):  
Antje Aschendorff ◽  
Robert Briggs ◽  
Goetz Brademann ◽  
Silke Helbig ◽  
Joachim Hornung ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Cochlear Implant ◽  
Temporal Bone ◽  
Clinical Investigation ◽  
Round Window ◽  
Electrode Array ◽  
Lateral Wall ◽  
Scala Tympani ◽  
Flat Panel ◽  
Insertion Depth

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.

scholarly journals Evaluation of the Relationship between the NRT-Ratio, Cochlear Anatomy, and Insertions Depth of Perimodiolar Cochlear Implant Electrodes

2015 ◽  
Vol 2015 ◽  
pp. 1-6 ◽  
Author(s):  
Philipp Mittmann ◽  
Grit Rademacher ◽  
Sven Mutze ◽  
Frederike Hassepass ◽  
Arneborg Ernst ◽  
...  
Keyword(s):  
Cochlear Implant ◽  
Electrode Array ◽  
Scala Tympani ◽  
Flat Panel ◽  
Insertion Depth ◽  
Tomography System ◽  
Neural Response Telemetry ◽  
Auditory Performance ◽  
The Relationship ◽  
Scala Vestibuli

The position of the cochlear implant electrode array within the scala tympani is essential for an optimal postoperative hearing benefit. If the electrode array changes in between the scalae intracochlearly (i.e., from scala tympani to scala vestibuli), a reduced auditory performance can be assumed. We established a neural response telemetry-ratio (NRT-ratio) which corresponds with the scalar position of the electrodes but shows within its limits a variability. The aim of this study was to determine if insertion depth angle or cochlea size influences the NRT-ratio. The intraoperative electrophysiological NRT data of 26 patients were evaluated. Using a flat panel tomography system, the position of the electrode array was evaluated radiologically. The insertion depth angle of the electrode, the cochlea size, and the NRT-ratio were calculated postoperatively. The radiological results were compared with the intraoperatively obtained electrophysiological data (NRT-ratio) and statistically evaluated. In all patients the NRT-ratio, the insertion depth angle, and the cochlea size could be determined. A significant correlation between insertional depth, cochlear size, and the NRT-ratio was not found. The NRT-ratio is a reliable electrophysiological tool to determine the scalar position of a perimodiolar electrode array. The NRT-ratio can be applied independent from insertion depth and cochlear size.

In Vivo Measurements of the Insertion Depth of Cochlear Implant Arrays Using Flat-Panel Volume Computed Tomography

2011 ◽  
Vol 32 (1) ◽  
pp. 152-157 ◽  
Author(s):  
Annett Trieger ◽  
Anja Schulze ◽  
Matthias Schneider ◽  
Thomas Zahnert ◽  
Dirk Mürbe
Keyword(s):  
Computed Tomography ◽  
Cochlear Implant ◽  
Flat Panel ◽  
Insertion Depth ◽  
In Vivo Measurements ◽  
Volume Computed Tomography

scholarly journals Effects of in vivo repositioning of slim modiolar electrodes on electrical thresholds and speech perception

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Sang-Yeon Lee ◽  
Young Seok Kim ◽  
Hyung Dong Jo ◽  
Yoonjoong Kim ◽  
Marge Carandang ◽  
...  
Keyword(s):  
Speech Perception ◽  
Cochlear Implant ◽  
Functional Outcomes ◽  
Cadaveric Study ◽  
Scala Tympani ◽  
Insertion Depth ◽  
Sentence Recognition ◽  
Open Set

AbstractThe slim modiolar electrode has been reported to ensure better modiolar proximity than previous conventional perimodiolar electrodes and consistently high scala tympani localization. Nonetheless, variability in modiolar proximity exists even among slim modiolar electrodes, still leaving room for further improvement of modiolar proximity, which may positively affect functional outcomes. Given this, the pull-back maneuver was reported to increase the modiolar proximity of slim modiolar electrodes in a cadaveric study, but in vivo repositioning effects remain to be established. Here we identified that the pull-back maneuver led to better modiolar proximity than conventional insertion while maintaining a similar angular insertion depth. Notably, the reduced electrode-modiolus distance from the pull-back maneuver was associated with significantly lower impedances across electrodes postoperatively as well as reduced intraoperative electrophysiological thresholds than conventional insertion. Among adult cochlear implant recipients, this maneuver resulted in significantly better sentence recognition scores at three months postoperatively when compared to those with a conventional insertion; however, this benefit was not observed at later intervals. Collectively, slim modiolar electrodes with the pull-back maneuver further enhance the modiolar proximity, possibly leading to better open-set sentence recognition, at least in the early postoperative stage.

scholarly journals Effect of Scala Tympani Height on Insertion Depth of Straight Cochlear Implant Electrodes

2020 ◽  
Vol 162 (5) ◽  
pp. 718-724 ◽  
Author(s):  
William G. Morrel ◽  
Jourdan T. Holder ◽  
Benoit M. Dawant ◽  
Jack H. Noble ◽  
Robert F. Labadie
Keyword(s):  
Cochlear Implant ◽  
Retrospective Review ◽  
Basilar Membrane ◽  
Lateral Wall ◽  
Scala Tympani ◽  
Tertiary Referral ◽  
Insertion Depth ◽  
Tertiary Referral Center ◽  
Relationship Of ◽  
The Relationship

Objective Studies suggest lateral wall (LW) scala tympani (ST) height decreases apically, which may limit insertion depth. No studies have investigated the relationship of LW ST height with translocation rate or location. Study Design Retrospective review. Setting Cochlear implant program at tertiary referral center. Subjects and Methods LW ST height was measured in preoperative images for patients with straight electrodes. Scalar location, angle of insertion depth (AID), and translocation depth were measured in postoperative images. Audiologic outcomes were tracked. Results In total, 177 ears were identified with 39 translocations (22%). Median AID was 443° (interquartile range [IQR], 367°-550°). Audiologic outcomes (126 ears) showed a small, significant correlation between consonant-nucleus-consonant (CNC) word score and AID ( r = 0.20, P = .027), although correlation was insignificant if translocation occurred ( r = 0.11, P = .553). Translocation did not affect CNC score ( P = .335). AID was higher for translocated electrodes (503° vs 445°, P = .004). Median translocation depth was 381° (IQR, 222°-399°). Median depth at which a 0.5-mm electrode would not fit within 0.1 mm of LW was 585° (IQR, 405°-585°). Median depth at which a 0.5-mm electrode would displace the basilar membrane by ≥0.1 mm was 585° (IQR, 518°-765°); this was defined as predicted translocation depth (PTD). Translocation rate was 39% for insertions deeper than PTD and 14% for insertions shallower than PTD ( P = .008). Conclusion AID and CNC are directly correlated for straight electrodes when not translocated. Translocations generally occur around 380° and are more common with deeper insertions due to decreasing LW ST height. Risk of translocation increases significantly after 580°.

Long-Term Follow-Up of Early Cochlear Implant Device Activation

2021 ◽  
pp. 1-11
Author(s):  
Stefanie Bruschke ◽  
Uwe Baumann ◽  
Timo Stöver
Keyword(s):  
Speech Recognition ◽  
Side Effects ◽  
Cochlear Implant ◽  
Surgical Techniques ◽  
Control Group ◽  
First Year ◽  
Safe Procedure ◽  
Sound Processor

Background: The cochlear implant (CI) is a standard procedure for the treatment of patients with severe to profound hearing loss. In the past, a standard healing period of 3–6 weeks occurred after CI surgery before the sound processor was initially activated. Advancements of surgical techniques and instruments allow an earlier initial activation of the processor within 14 days after surgery. Objective: Evaluation of the early CI device activation after CI surgery within 14 days, comparison to the first activation after 4–6 weeks, and assessment of the feasibility and safety of the early fitting over a 12 month observation period were the objectives of this study. Method: In a prospective study, 127 patients scheduled for CI surgery were divided into early fitting group (EF, n = 67) and control group (CG, n = 60). Individual questionnaires were used to evaluate medical and technical outcomes of the EF. Medical side effects, speech recognition, and follow-up effort were compared with the CG within the first year after CI surgery. Results: The early fitting was feasible in 97% of the EF patients. In the EF, the processor was activated 25 days earlier than in the CG. No major complications were observed in either group. At the follow-up appointments, side effects such as pain and balance problems occurred with comparable frequency in both groups. At initial fitting, the EF showed a significantly higher incidence of medical minor complications (p < 0.05). When developing speech recognition within the first year of CI use, no difference was observed. Furthermore, the follow-up effort within the first year after CI surgery was comparable in both groups. Conclusions: Early fitting of the sound processor is a feasible and safe procedure with comparable follow-up effort. Although more early minor complications were observed in the EF, there were no long-term wound healing problems caused by the early fitting. Regular inspection of the magnet strength is recommended as part of the CI follow-up since postoperative wound swelling must be expected. The early fitting procedure enabled a clear reduction in the waiting time between CI surgery and initial sound processor activation.

Role of Computed Tomography and Magnetic Resonance Imaging in detecting the Prevalence of inner ear anomalies among cochlear implant candidates

QJM ◽  
2021 ◽  
Vol 114 (Supplement_1) ◽  
Author(s):  
Alaa Nasser Hussain Zaher ◽  
Tougan Taha Abd El Aziz ◽  
Ahmed Samy Abdelrahman
Keyword(s):  
Magnetic Resonance Imaging ◽  
Computed Tomography ◽  
Hearing Loss ◽  
Cochlear Implant ◽  
Inner Ear ◽  
Resonance Imaging ◽  
High Resolution Computed Tomography ◽  
Vestibular Aqueduct ◽  
Incomplete Partition ◽  
Ear Anomalies

Abstract Background Hearing loss management using cochlear implants in patients with inner ear anomalies has long been discussed in the otology community. Magnetic resonances imaging (B,/IRI) and Computed tomography (CT) play important roles in the preoperative assessment of inner ear abnormalities such as cochlear nerve deficiency and variant anatomy as these abnormalities may not only affect the decision of the implantation procedure or the patient's prognosis regarding auditory improvement, but also the risk of complications. Objective To examine the prevalence of inner ear anomalies among cochlear implant recipients in patients with congenital sensorineural hearing loss among the pediatric age group in the Demerdash hospital, Ain Shams university using High resolution computed tomography (HRCT) and MRI imaging. Methods A retrospective descriptive study over the course of 9 months that included all patients that are candidates for cochlear implant referred to the Radiology department, Ain Shams University Hospitals for a preoperative imaging in the form of CT and VIRI scans. Results CT and MRI scans of 33 patients who had congenital hearing loss and were candidates for cochlear implantation with total 66 ears were reviewed. Inner ear anomalies were identified in 8 patients representing a prevalence (24.2%) with 14 ear diseased. Anomalies were seen bilaterally in 6 patients and unilaterally in 2 patients. Among the 14 diseased ear, 9 ears (64.3%) were seen with incomplete partition Il, 7 ears (50%) were seen with enlarged vestibular aqueduct, 4 ears (28.6%) were seen with cochlear hypoplasia, 3 ears (21.4%) were seen with semicircular canal aplasia, 2 ears (14.3%) were seen with incomplete partition type I, 2 ears (14.3%) were seen with cochlear nerve aplasia, 2 ears with cochlear aplasia (14.3%), I ear (7.1%) was seen with common cavity ear (7.1%) with complete labyrinthine aplasia. Conclusion Prevalence of inner ear anomalies among cochlear implant candidates was 24.2%. This result is consistent with results worldwide and the most common anomalies were Incomplete partition Il and large vestibular aqueduct. Abbreviations Computed tomography (CT), Magnetic resonance imaging (MRI), High resolution computed tomography (HRCT), Internal auditory canal (IAC), Cerebellopontine angle (CPA).

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