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Weiss NM, Breitsprecher T, Wozniak M, Bächinger D, Völter C, Mlynski R, Van de Heyning P, Van Rompaey V, Dazert S. Comparing linear and non-linear models to estimate the appropriate cochlear implant electrode array length-are current methods precise enough? Eur Arch Otorhinolaryngol 2024; 281:43-49. [PMID: 37466660 PMCID: PMC10764384 DOI: 10.1007/s00405-023-08064-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2023] [Accepted: 06/09/2023] [Indexed: 07/20/2023]
Abstract
PURPOSE In cochlear implantation with flexible lateral wall electrode arrays, a cochlear coverage (CC) range between 70% and 80% is considered ideal for optimal speech perception. To achieve this CC, the cochlear implant (CI) electrode array has to be chosen according to the individual cochlear duct length (CDL). Here, we mathematically analyzed the suitability of different flexible lateral wall electrode array lengths covering between 70% and 80% of the CDL. METHODS In a retrospective cross-sectional study preoperative high-resolution computed tomography (HRCT) from patients undergoing cochlear implantation was investigated. The CDL was estimated using an otosurgical planning software and the CI electrode array lengths covering 70-80% of the CDL was calculated using (i) linear and (ii) non-linear models. RESULTS The analysis of 120 HRCT data sets showed significantly different model-dependent CDL. Significant differences between the CC of 70% assessed from linear and non-linear models (mean difference: 2.5 mm, p < 0.001) and the CC of 80% assessed from linear and non-linear models (mean difference: 1.5 mm, p < 0.001) were found. In up to 25% of the patients none of the existing flexible lateral wall electrode arrays fit into this range. In 59 cases (49,2%) the models did not agree on the suitable electrode arrays. CONCLUSIONS The CC varies depending on the underlying CDL approximation, which critically influences electrode array choice. Based on the literature, we hypothesize that the non-linear method systematically overestimates the CC and may lead to rather too short electrode array choices. Future studies need to assess the accuracy of the individual mathematical models.
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Affiliation(s)
- Nora M Weiss
- Department of Otorhinolaryngology-Head and Neck Surgery, Ruhr-University Bochum, St. Elisabeth-Hospital Bochum, Bochum, Germany.
- Department of Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium.
- International Graduate School of Neuroscience (IGSN), Ruhr-University Bochum, Bochum, Germany.
| | - Tabita Breitsprecher
- Department of Otorhinolaryngology-Head and Neck Surgery, Ruhr-University Bochum, St. Elisabeth-Hospital Bochum, Bochum, Germany
| | - Martin Wozniak
- MED-EL Elektromedizinische Geräte Deutschland GmbH, Starnberg, Deutschland
| | - David Bächinger
- Department of Otorhinolaryngology-Head and Neck Surgery, Ruhr-University Bochum, St. Elisabeth-Hospital Bochum, Bochum, Germany
| | - Christiane Völter
- Department of Otorhinolaryngology-Head and Neck Surgery, Ruhr-University Bochum, St. Elisabeth-Hospital Bochum, Bochum, Germany
| | - Robert Mlynski
- Department of Otorhinolaryngology, Head and Neck Surgery, "Otto Körner", University, Rostock, Germany
| | - Paul Van de Heyning
- Department of Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
- Department of Otorhinolaryngology and Head & Neck Surgery, Antwerp University Hospital, Antwerp, Belgium
| | - Vincent Van Rompaey
- Department of Translational Neurosciences, Faculty of Medicine and Health Sciences, University of Antwerp, Antwerp, Belgium
- Department of Otorhinolaryngology and Head & Neck Surgery, Antwerp University Hospital, Antwerp, Belgium
| | - Stefan Dazert
- Department of Otorhinolaryngology-Head and Neck Surgery, Ruhr-University Bochum, St. Elisabeth-Hospital Bochum, Bochum, Germany
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Alothman N, Almuhawas F, Badghaish R, Alotaibi AH, Alhabib SF, Alzhrani F, Hagr A. Cochlear Implantation in Pediatrics: The Effect of Cochlear Coverage. J Pers Med 2023; 13:jpm13030562. [PMID: 36983743 PMCID: PMC10051355 DOI: 10.3390/jpm13030562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2023] [Revised: 03/10/2023] [Accepted: 03/17/2023] [Indexed: 03/30/2023] Open
Abstract
The effect of insertion depth and position of cochlear implant (CI) electrode arrays on speech perception remains unclear. This study aimed to determine the relationship between cochlear coverage and speech performance in children with prelingual hearing loss with CI. Pure tone audiometry (PTA) and speech audiometry, including speech reception threshold (SRT) using spondee words and speech discrimination score (SDS) using phonetically balanced monosyllabic words, were tested. The Categories of Auditory Performance (CAP) and Speech Intelligibility Rating (SIR) scales were also used. Thirty-one ears were implanted with the FLEX 28 electrode array, and 54 with the FORM 24 were included in the current study. For the studied ear, the mean cochlear duct length was 30.82 ± 2.24 mm; the mean cochlear coverage was 82.78 ± 7.49%. Cochlear coverage was a significant negative predictor for the mean pure tone threshold across frequecnies of 0.5, 1, 2, and 4 kHz (PTA4) (p = 0.019). Cochlear coverage was a significant positive predictor of SDS (p = 0.009). In children with cochlear coverage ≥ 82.78%, SDS was significantly better than in those with coverage < 82.78% (p = 0.04). Cochlear coverage was not a significant predictor of the SRT, CAP, or SIR. In conclusion, the cochlear coverage of the CI electrode array has an impact on the users' SDS. Further long-term studies with larger sample sizes should be conducted to address the most critical factors affecting CI recipients' outcomes.
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Affiliation(s)
- Noura Alothman
- Health Communication Sciences, College of Health and Rehabilitation Sciences, Princess Nourah bint Abdulrahman University, Riyadh 84428, Saudi Arabia
| | - Fida Almuhawas
- King Abdullah Ear Specialist Center (KAESC), College of Medicine, King Saud University, Riyadh 11411, Saudi Arabia
| | - Reem Badghaish
- King Abdullah Ear Specialist Center (KAESC), College of Medicine, King Saud University, Riyadh 11411, Saudi Arabia
| | - Al Hanouf Alotaibi
- King Abdullah Ear Specialist Center (KAESC), College of Medicine, King Saud University, Riyadh 11411, Saudi Arabia
| | - Salman F Alhabib
- King Abdullah Ear Specialist Center (KAESC), College of Medicine, King Saud University, Riyadh 11411, Saudi Arabia
| | - Farid Alzhrani
- King Abdullah Ear Specialist Center (KAESC), College of Medicine, King Saud University, Riyadh 11411, Saudi Arabia
| | - Abdulrahman Hagr
- King Abdullah Ear Specialist Center (KAESC), College of Medicine, King Saud University, Riyadh 11411, Saudi Arabia
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Kim Y, Choi BY. Precision Medicine Approach to Cochlear Implantation. Clin Exp Otorhinolaryngol 2022; 15:299-309. [PMID: 36397263 PMCID: PMC9723282 DOI: 10.21053/ceo.2022.01382] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2022] [Revised: 10/31/2022] [Accepted: 11/02/2022] [Indexed: 11/11/2022] Open
Abstract
In the early days of cochlear implantation (CI) surgery, when the types of electrodes were limited and the etiology of sensorineural hearing loss (SNHL) was not well understood, the one-size-fits-all approach to CI held true, as in all other fields. However, in the era of personalized medicine, there have been attempts to associate CI performance with the etiology of SNHL and to establish customized surgical techniques that can maximize performance according to individual cochlear dimensions. Personalized genomic-driven assessments of CI candidates and a better understanding of genotype-phenotype correlations could provide clinically applicable diagnostic and prognostic information about questions such as who, how, and when to implant. Rigorous and strategic imaging assessments also provide better insights into the anatomic etiology of SNHL and cochlear dimensions, leading to individualized surgical techniques to augment CI outcomes. Furthermore, the precision medicine approach to CI is not necessarily limited to preoperative planning, but can be extended to either intraoperative electrode positioning or even the timing of the initial switch-on. In this review, we discuss the implications of personalized diagnoses (both genetic and nongenetic) on the planning and performance of CI in patients with prelingual and postlingual SNHL.
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Affiliation(s)
- Yehree Kim
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Bundang Hospital, Seongnam, Korea
| | - Byung Yoon Choi
- Department of Otorhinolaryngology-Head and Neck Surgery, Seoul National University Bundang Hospital, Seongnam, Korea
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Walia A, Shew MA, Lefler SM, Kallogjeri D, Wick CC, Holden TA, Durakovic N, Ortmann AJ, Herzog JA, Buchman CA. Is Characteristic Frequency Limiting Real-Time Electrocochleography During Cochlear Implantation? Front Neurosci 2022; 16:915302. [PMID: 35937872 PMCID: PMC9354607 DOI: 10.3389/fnins.2022.915302] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Accepted: 06/15/2022] [Indexed: 12/05/2022] Open
Abstract
Objectives Electrocochleography (ECochG) recordings during cochlear implantation have shown promise in estimating the impact on residual hearing. The purpose of the study was (1) to determine whether a 250-Hz stimulus is superior to 500-Hz in detecting residual hearing decrement and if so; (2) to evaluate whether crossing the 500-Hz tonotopic, characteristic frequency (CF) place partly explains the problems experienced using 500-Hz. Design Multifrequency ECochG comprising an alternating, interleaved acoustic complex of 250- and 500-Hz stimuli was used to elicit cochlear microphonics (CMs) during insertion. The largest ECochG drops (≥30% reduction in CM) were identified. After insertion, ECochG responses were measured using the individual electrodes along the array for both 250- and 500-Hz stimuli. Univariate regression was used to predict whether 250- or 500-Hz CM drops explained low-frequency pure tone average (LFPTA; 125-, 250-, and 500-Hz) shift at 1-month post-activation. Postoperative CT scans were performed to evaluate cochlear size and angular insertion depth. Results For perimodiolar insertions (N = 34), there was a stronger linear correlation between the largest ECochG drop using 250-Hz stimulus and LFPTA shift (r = 0.58), compared to 500-Hz (r = 0.31). The 250- and 500-Hz CM insertion tracings showed an amplitude peak at two different locations, with the 500-Hz peak occurring earlier in most cases than the 250-Hz peak, consistent with tonotopicity. When using the entire array for recordings after insertion, a maximum 500-Hz response was observed 2-6 electrodes basal to the most-apical electrode in 20 cases (58.9%). For insertions where the apical insertion angle is >350 degrees and the cochlear diameter is <9.5 mm, the maximum 500-Hz ECochG response may occur at the non-apical most electrode. For lateral wall insertions (N = 14), the maximum 250- and 500-Hz CM response occurred at the most-apical electrode in all but one case. Conclusion Using 250-Hz stimulus for ECochG feedback during implantation is more predictive of hearing preservation than 500-Hz. This is due to the electrode passing the 500-Hz CF during insertion which may be misidentified as intracochlear trauma; this is particularly important in subjects with smaller cochlear diameters and deeper insertions. Multifrequency ECochG can be used to differentiate between trauma and advancement of the apical electrode beyond the CF.
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Fan Y, Zhang D, Banalagay R, Wang J, Noble JH, Dawant BM. Hybrid active shape and deep learning method for the accurate and robust segmentation of the intracochlear anatomy in clinical head CT and CBCT images. J Med Imaging (Bellingham) 2021; 8:064002. [PMID: 34853805 DOI: 10.1117/1.jmi.8.6.064002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2020] [Accepted: 11/08/2021] [Indexed: 11/14/2022] Open
Abstract
Purpose: Robust and accurate segmentation methods for the intracochlear anatomy (ICA) are a critical step in the image-guided cochlear implant programming process. We have proposed an active shape model (ASM)-based method and a deep learning (DL)-based method for this task, and we have observed that the DL method tends to be more accurate than the ASM method while the ASM method tends to be more robust. Approach: We propose a DL-based U-Net-like architecture that incorporates ASM segmentation into the network. A quantitative analysis is performed on a dataset that consists of 11 cochlea specimens for which a segmentation ground truth is available. To qualitatively evaluate the robustness of the method, an experienced expert is asked to visually inspect and grade the segmentation results on a clinical dataset made of 138 image volumes acquired with conventional CT scanners and of 39 image volumes acquired with cone beam CT (CBCT) scanners. Finally, we compare training the network (1) first with the ASM results, and then fine-tuning it with the ground truth segmentation and (2) directly with the specimens with ground truth segmentation. Results: Quantitative and qualitative results show that the proposed method increases substantially the robustness of the DL method while having only a minor detrimental effect (though not significant) on its accuracy. Expert evaluation of the clinical dataset shows that by incorporating the ASM segmentation into the DL network, the proportion of good segmentation cases increases from 60/177 to 119/177 when training only with the specimens and increases from 129/177 to 151/177 when pretraining with the ASM results. Conclusions: A hybrid ASM and DL-based segmentation method is proposed to segment the ICA in CT and CBCT images. Our results show that combining DL and ASM methods leads to a solution that is both robust and accurate.
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Affiliation(s)
- Yubo Fan
- Vanderbilt University, Department of Computer Science, Nashville, Tennessee, United States
| | | | - Rueben Banalagay
- Vanderbilt University, Department of Electrical and Computer Engineering, Nashville, Tennessee, United States
| | - Jianing Wang
- Vanderbilt University, Department of Electrical and Computer Engineering, Nashville, Tennessee, United States
| | - Jack H Noble
- Vanderbilt University, Department of Electrical and Computer Engineering, Nashville, Tennessee, United States
| | - Benoit M Dawant
- Vanderbilt University, Department of Electrical and Computer Engineering, Nashville, Tennessee, United States
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Eser MB, Atalay B, Dogan MB, Gündüz N, Kalcioglu MT. Measuring 3D Cochlear Duct Length on MRI: Is It Accurate and Reliable? AJNR Am J Neuroradiol 2021; 42:2016-2022. [PMID: 34593380 DOI: 10.3174/ajnr.a7287] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2021] [Accepted: 07/25/2021] [Indexed: 11/07/2022]
Abstract
BACKGROUND AND PURPOSE Prior studies have evaluated cochlear length using CT to select the most suitable cochlear implants and obtain patient-specific anatomy. This study aimed to test the accuracy and reliability of cochlear lateral wall length measurements using 3D MR imaging. MATERIALS AND METHODS Two observers measured the cochlear lateral wall length of 35 patients (21 men) with postlingual hearing loss using CT and MR imaging. The intraclass correlation coefficient (with 95% confidence intervals) was used to evaluate intraobserver and interobserver reliability for the 3D cochlear measurements. RESULTS The mean age of the participants was 39.85 (SD, 16.60) years. Observer 1 measured the mean lateral wall length as 41.52 (SD, 2.25) mm on CT and 41.44 (SD, 2.18) mm on MR imaging, with a mean difference of 0.08 mm (95% CI, -0.11 to 0.27 mm), while observer 2 measured the mean lateral wall length as 41.74 (SD, 2.69) mm on CT and 42.34 (SD, 2.53) mm on MR imaging, with a mean difference of -0.59 mm (95% CI, -1.00 to -0.20 mm). An intraclass correlation coefficient value of 0.90 (95% CI, 0.84-0.94) for CT and 0.69 (95% CI, 0.46-0.82) for MR imaging was obtained for the interobserver reliability for the full-turn cochlear lateral wall length. CONCLUSIONS CT-based 3D cochlear measurements show excellent intraobserver and interobserver reliability, while MR imaging-based lateral wall length measurements have good-to-excellent intraobserver reliability and moderate interobserver reliability. These results corroborate the use of CT for 3D cochlear measurements as a reference method and demonstrate MR imaging to be an alternative acquisition technique with comparably reliable results.
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Affiliation(s)
- M B Eser
- From the Departments of Radiology (M.B.E., B.A., M.B.D., N.G.)
| | - B Atalay
- From the Departments of Radiology (M.B.E., B.A., M.B.D., N.G.)
| | - M B Dogan
- From the Departments of Radiology (M.B.E., B.A., M.B.D., N.G.)
| | - N Gündüz
- From the Departments of Radiology (M.B.E., B.A., M.B.D., N.G.)
| | - M T Kalcioglu
- Otorhinolaryngology-Head and Neck Surgery (M.T.K.), Faculty of Medicine, Goztepe Prof. Dr. Suleyman Yalcin City Hospital, Istanbul, Turkey
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Eser MB, Atalay B, Kalcıoğlu MT. Is Cochlear Length Related to Congenital Sensorineural Hearing Loss: Preliminary Data. J Int Adv Otol 2021; 17:1-8. [PMID: 32147598 DOI: 10.5152/iao.2020.7863] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
OBJECTIVES This study used the data from patients with congenital sensorineural hearing loss (CSNHL) and those with normal hearing to measure and compare the length of the cochlea with high-resolution computed tomography (HRCT). MATERIALS AND METHODS HRCT images of patients who were diagnosed with CSNHL and were candidates for cochlear implantation were evaluated retrospectively. Sixty-three ears of 33 patients were included in the study. The control group comprised 66 ears of 33 individuals. The measurements were conducted by an experienced radiologist, using three-dimensional curved multiplanar reconstruction. All the measurements were performed thrice, and the average was calculated. RESULTS The data were distributed normally. The lengths of the cochlear components for the CSNHL and control groups were as follows: basal turn 21.66±1.01 (21.30-22.02) and 22.57±0.68 (22.32-22.81) mm, middle turn 11.58±0.69 (11.34-11.83) and 12.39±0.46 (12.23-12.56) mm, and apical turn 6.45±0.92 (6.12-6.77) and 7.12±0.65 (6.89-7.35) mm, respectively. The mean cochlear lateral wall (LW) length was significantly shorter in the CSNHL patients [39.71±1.32 (39.25-40.18) mm] than in the controls [42.09±1.17 (41.67-42.51) mm], (p<0.001). The intra-rater reliability was 0.878 (confidence interval 95%: 0.841-0.908 p<0.001). The cut-off value was 40.81 mm (sensitivity: 0.91, specificity: 0.94, and accuracy: 0.90). CONCLUSION There were microanatomic dissimilarities between the length of the cochlea in subjects from the CSNHL group and those from the control group.
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Affiliation(s)
- Mehmet Bilgin Eser
- Department of Radiology, Istanbul Medeniyet University School of Medicine, Istanbul, Turkey
| | - Başak Atalay
- Department of Radiology, Istanbul Medeniyet University School of Medicine, Istanbul, Turkey
| | - Mahmut Tayyar Kalcıoğlu
- Department of Otorhinolaryngology - Head and Neck Surgery, Istanbul Medeniyet University School of Medicine, İstanbul, Turkey
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CT imaging-based approaches to cochlear duct length estimation-a human temporal bone study. Eur Radiol 2021; 32:1014-1023. [PMID: 34463797 PMCID: PMC8794899 DOI: 10.1007/s00330-021-08189-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 06/18/2021] [Accepted: 06/30/2021] [Indexed: 01/12/2023]
Abstract
Objectives Knowledge about cochlear duct length (CDL) may assist electrode choice in cochlear implantation (CI). However, no gold standard for clinical applicable estimation of CDL exists. The aim of this study is (1) to determine the most reliable radiological imaging method and imaging processing software for measuring CDL from clinical routine imaging and (2) to accurately predict the insertion depth of the CI electrode. Methods Twenty human temporal bones were examined using different sectional imaging techniques (high-resolution computed tomography [HRCT] and cone beam computed tomography [CBCT]). CDL was measured using three methods: length estimation using (1) a dedicated preclinical 3D reconstruction software, (2) the established A-value method, and (3) a clinically approved otosurgical planning software. Temporal bones were implanted with a 31.5-mm CI electrode and measurements were compared to a reference based on the CI electrode insertion angle measured by radiographs in Stenvers projection (CDLreference). Results A mean cochlear coverage of 74% (SD 7.4%) was found. The CDLreference showed significant differences to each other method (p < 0.001). The strongest correlation to the CDLreference was found for the otosurgical planning software-based method obtained from HRCT (CDLSW-HRCT; r = 0.87, p < 0.001) and from CBCT (CDLSW-CBCT; r = 0.76, p < 0.001). Overall, CDL was underestimated by each applied method. The inter-rater reliability was fair for the CDL estimation based on 3D reconstruction from CBCT (CDL3D-CBCT; intra-class correlation coefficient [ICC] = 0.43), good for CDL estimation based on 3D reconstruction from HRCT (CDL3D-HRCT; ICC = 0.71), poor for CDL estimation based on the A-value method from HRCT (CDLA-HRCT; ICC = 0.29), and excellent for CDL estimation based on the A-value method from CBCT (CDLA-CBCT; ICC = 0.87) as well as for the CDLSW-HRCT (ICC = 0.94), CDLSW-CBCT (ICC = 0.94) and CDLreference (ICC = 0.87). Conclusions All approaches would have led to an electrode choice of rather too short electrodes. Concerning treatment decisions based on CDL measurements, the otosurgical planning software-based method has to be recommended. The best inter-rater reliability was found for CDLA-CBCT, for CDLSW-HRCT, for CDLSW-CBCT, and for CDLreference. Key Points • Clinically applicable calculations using high-resolution CT and cone beam CT underestimate the cochlear size. • Ten percent of cochlear duct length need to be added to current calculations in order to predict the postoperative CI electrode position. • The clinically approved otosurgical planning software-based method software is the most suitable to estimate the cochlear duct length and shows an excellent inter-rater reliability.
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The Use of Clinically Measurable Cochlear Parameters in Cochlear Implant Surgery as Indicators for Size, Shape, and Orientation of the Scala Tympani. Ear Hear 2021; 42:1034-1041. [PMID: 33480625 DOI: 10.1097/aud.0000000000000998] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVES (1) To assess variations of the human intracochlear anatomy and quantify factors which might be relevant for cochlear implantation (CI) regarding surgical technique and electrode design. (2) Search for correlations of these factors with clinically assessable measurements. DESIGN Human temporal bone study with micro computed tomography (μCT) data and analysis of intracochlear geometrical variations: μCT data of 15 fresh human temporal bones was generated, and the intracochlear lumina scala tympani (ST) and scala vestibuli were manually segmented using custom software specifically designed for accurate cochlear segmentation. The corresponding datasets were processed yielding 15 detailed, three-dimensional cochlear models which were investigated in terms of the scalae height, cross-sectional size, and rotation as well as the interrelation of these factors and correlations to others. RESULTS The greatest anatomical variability was observed within the round window region of the cochlea (basal 45°), especially regarding the cross-sectional size of the ST and its orientation relative to the scala vestibuli, which were found to be correlated (p < 0.001). The cross-sectional height of the ST changes substantially for both increasing cochlear angles and lateral wall distances. Even small cochleae were found to contain enough space for all commercially available CI arrays. Significant correlations of individual intracochlear parameters to clinically assessable ones were found despite the small sample size. CONCLUSION While there is generally enough space within the ST for CI, strong intracochlear anatomical variations could be observed highlighting the relevance of both soft surgical technique as well as a highly flexible and self-adapting cochlear implant electrode array design. Cochlear dimensions (especially at the round window) could potentially be used to indicate surgically challenging anatomies.
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Computed Tomography-Based Measurements of the Cochlear Duct: Implications for Cochlear Implant Pitch Tuning. Ear Hear 2021; 42:732-743. [PMID: 33538429 DOI: 10.1097/aud.0000000000000977] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
OBJECTIVES To determine the sources of variability for cochlear duct length (CDL) measurements for the purposes of fine-tuning cochlear implants (CI) and to propose a set of standardized landmarks for computed tomography (CT) pitch mapping. DESIGN This was a retrospective cohort study involving 21 CI users at a tertiary referral center. The intervention involved flat-panel CT image acquisition and secondary reconstructions of CIs in vivo. The main outcome measures were CDL measurements, CI electrode localization measurements, and frequency calculations. RESULTS Direct CT-based measurements of CI and intracochlear landmarks are methodologically valid, with a percentage of error of 1.0% ± 0.9%. Round window (RW) position markers (anterior edge, center, or posterior edge) and bony canal wall localization markers (medial edge, duct center, or lateral edge) significantly impact CDL calculations [F(2, 78) = 9.9, p < 0.001 and F(2, 78) = 1806, p < 0.001, respectively]. These pitch distortions could be as large as 11 semitones. When using predefined anatomical landmarks, there was still a difference between researchers [F(2, 78) = 12.5; p < 0.001], but the average variability of electrode location was reduced to differences of 1.6 semitones (from 11 semitones. CONCLUSIONS A lack of standardization regarding RW and bony canal wall landmarks results in great CDL measurement variability and distorted pitch map calculations. We propose using the posterior edge of the RW and lateral bony wall as standardized anatomical parameters for CDL calculations in CI users to improve pitch map calculations. More accurate and precise pitch maps may improve CI-associated pitch outcomes.
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Rak K, Ilgen L, Taeger J, Schendzielorz P, Voelker J, Kaulitz S, Müller-Graff FT, Kurz A, Neun T, Hagen R. Influence of cochlear parameters on the current practice in cochlear implantation : Development of a concept for personalized medicine. HNO 2021; 69:24-30. [PMID: 33459799 DOI: 10.1007/s00106-020-00969-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/11/2020] [Indexed: 11/26/2022]
Abstract
Since the introduction of cochlear implants into clinical routine, the interest in measuring cochlear parameters, particularly the cochlear duct length (CDL) has increased, since these can have an influence on the correct selection of the electrode. On the one hand, coverage of an optimal frequency band is relevant for a good audiological result, and on the other hand, cochlear trauma due to too deep insertion or displacement of the electrode must be avoided. Cochlear implants stimulate the spiral ganglion cells (SGC). The number of SGC and particularly their distribution can also have an influence on the function of a cochlear implant. In addition, the frequency assignment of each electrode contact can play a decisive role in the postoperative success, since the frequency distribution of the human cochlea with varying CDL shows substantial interindividual differences. The aim of this work is to provide an overview of the methods used to determine the cochlear parameters as well as of relevant studies on the CDL, the number and distribution of SGZ, and the frequency assignment of electrode contacts. Based on this, a concept for individualized cochlear implantation will be presented. In summary, this work should help to promote individualized medicine in the field of cochlear implants in the future, in order to overcome current limitations and optimize audiological outcomes.
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Affiliation(s)
- K Rak
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany.
| | - L Ilgen
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany
| | - J Taeger
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany
| | - P Schendzielorz
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany
| | - J Voelker
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany
| | - S Kaulitz
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany
| | - F-T Müller-Graff
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany
| | - A Kurz
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany
| | - T Neun
- Institute for Diagnostic and Interventional Neuroradiology, University Hospital Würzburg, Würzburg, Germany
| | - R Hagen
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany
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[Influence of cochlear parameters on the current practice in cochlear implantation : Development of a concept for personalized medicine. German version]. HNO 2020; 69:943-951. [PMID: 33315129 DOI: 10.1007/s00106-020-00968-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/21/2020] [Indexed: 10/22/2022]
Abstract
Since the introduction of cochlear implants into clinical routine, the interest in measuring cochlear parameters, particularly the cochlear duct length (CDL) has increased, since these can have an influence on the correct selection of the electrode. On the one hand, coverage of an optimal frequency band is relevant for a good audiological result, and on the other hand, cochlear trauma due to too deep insertion or displacement of the electrode must be avoided. Cochlear implants stimulate the spiral ganglion cells (SGC). The number of SGC and particularly their distribution can also have an influence on the function of a cochlear implant. In addition, the frequency assignment of each electrode contact can play a decisive role in the postoperative success, since the frequency distribution of the human cochlea with varying CDL shows substantial interindividual differences. The aim of this work is to provide an overview of the methods used to determine the cochlear parameters as well as of relevant studies on the CDL, the number and distribution of SGZ, and the frequency assignment of electrode contacts. Based on this, a concept for individualized cochlear implantation will be presented. In summary, this work should help to promote individualized medicine in the field of cochlear implants in the future, in order to overcome current limitations and optimize audiological outcomes.
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Modiolar Proximity of Slim Modiolar Electrodes and Cochlear Duct Length: Correlation for Potential Basis of Customized Cochlear Implantation With Perimodiolar Electrodes. Ear Hear 2020; 42:323-333. [PMID: 32826506 DOI: 10.1097/aud.0000000000000920] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
OBJECTIVES Recent studies have shown that cochlear duct length (CDL) varies among individuals and could significantly influence the final position of the electrode and its trajectory in the cochlea. Given this, we hypothesized that the degree of modiolar proximity of novel slim modiolar electrodes, such as CI532 and CI632, can also be affected by CDL. To test this hypothesis, we retrospectively evaluated individual CDL to determine if there is any significant correlation of CDL with degree of modiolar proximity. METHODS Fifty-one ears from 38 subjects implanted with slim modiolar electrodes by a single surgeon through the round window approach using the pull-back technique were included. Our cohort was classified according to the deafness onset (congenital versus postlingual) and the degree of modiolar proximity (less versus tight) with reference to the spiral diameter made by the slim modiolar electrodes in situ on transorbital x ray. We then analyzed the CDL and its metrics using a readily available surgical preplanning tool (OTOPLAN) to obtain comparable data. RESULTS Among 30 ears associated with congenital deafness, 9 ears (30%) showed less modiolar proximity, while none of the 21 ears from 19 subjects with postlingual deafness exhibited "less modiolar proximity" based on our criteria. In this study, CDL showed significant variation among subjects. Importantly, a significant inverse correlation between spiral diameter and CDL (ρ = -0.581, p < 0.001) was found, showing that shorter CDLs have longer spiral diameter and less modiolar proximity. Moreover, further pull-back technique characterized by pulling out the electrode a little bit more in cases with shorter CDL, if not always, exhibited tighter modiolar proximity. CONCLUSION A preponderance of less modiolar proximity of the electrode was observed exclusively among congenital deafness cases, demonstrated by a less tight spiral configuration even under the pull-back technique. Our data suggest that shorter CDL is associated with a less tight spiral configuration of slim modiolar electrodes postoperatively. Depending on the insertion technique, the differential degree of modiolar proximity of slim modiolar electrodes can be alleviated in cases with short CDL, which justifies cochlear duct length-based customized insertion of slim modiolar electrodes.
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Comment on "The Effect of Cochlear Size on Cochlear Implantation Outcomes". BIOMED RESEARCH INTERNATIONAL 2020; 2020:5674547. [PMID: 32802858 PMCID: PMC7415093 DOI: 10.1155/2020/5674547] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Accepted: 07/16/2020] [Indexed: 11/18/2022]
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Helpard L, Li H, Rask-Andersen H, Ladak HM, Agrawal SK. Characterization of the human helicotrema: implications for cochlear duct length and frequency mapping. J Otolaryngol Head Neck Surg 2020; 49:2. [PMID: 31907040 PMCID: PMC6945762 DOI: 10.1186/s40463-019-0398-8] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Accepted: 12/23/2019] [Indexed: 11/15/2022] Open
Abstract
Background Despite significant anatomical variation amongst patients, cochlear implant frequency-mapping has traditionally followed a patient-independent approach. Basilar membrane (BM) length is required for patient-specific frequency-mapping, however cochlear duct length (CDL) measurements generally extend to the apical tip of the entire cochlea or have no clearly defined end-point. By characterizing the length between the end of the BM and the apical tip of the entire cochlea (helicotrema length), current CDL models can be corrected to obtain the appropriate BM length. Synchrotron radiation phase-contrast imaging has made this analysis possible due to the soft-tissue contrast through the entire cochlear apex. Methods Helicotrema linear length and helicotrema angular length measurements were performed on synchrotron radiation phase-contrast imaging data of 14 cadaveric human cochleae. On a sub-set of six samples, the CDL to the apical tip of the entire cochlea (CDLTIP) and the BM length (CDLBM) were determined. Regression analysis was performed to assess the relationship between CDLTIP and CDLBM. Results The mean helicotrema linear length and helicotrema angular length values were 1.6 ± 0.9 mm and 67.8 ± 37.9 degrees, respectively. Regression analysis revealed the following relationship between CDLTIP and CDLBM: CDLBM = 0.88(CDLTIP) + 3.71 (R2 = 0.995). Conclusion This is the first known study to characterize the length of the helicotrema in the context of CDL measurements. It was determined that the distance between the end of the BM and the tip of the entire cochlea is clinically consequential. A relationship was determined that can predict the BM length of an individual patient based on their respective CDL measured to the apical tip of the cochlea.
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Affiliation(s)
- Luke Helpard
- School of Biomedical Engineering, Western University, London, Ontario, Canada.
| | - Hao Li
- Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden.,Department of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden
| | - Helge Rask-Andersen
- Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden.,Department of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden
| | - Hanif M Ladak
- School of Biomedical Engineering, Western University, London, Ontario, Canada.,Department of Otolaryngology - Head and Neck Surgery, Western University, London, Ontario, Canada.,Department of Medical Biophysics, Western University, London, Ontario, Canada.,Department of Electrical and Computer Engineering, Western University, London, Ontario, Canada
| | - Sumit K Agrawal
- School of Biomedical Engineering, Western University, London, Ontario, Canada.,Department of Otolaryngology - Head and Neck Surgery, Western University, London, Ontario, Canada.,Department of Medical Biophysics, Western University, London, Ontario, Canada.,Department of Electrical and Computer Engineering, Western University, London, Ontario, Canada
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Nateghifard K, Low D, Awofala L, Srikanthan D, Kuthubutheen J, Daly M, Chan H, Irish J, Chen J, Lin V, Le TN. Cone beam CT for perioperative imaging in hearing preservation Cochlear implantation - a human cadaveric study. J Otolaryngol Head Neck Surg 2019; 48:65. [PMID: 31753027 PMCID: PMC6873551 DOI: 10.1186/s40463-019-0388-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Accepted: 11/01/2019] [Indexed: 11/17/2022] Open
Abstract
Background Knowledge of the cochlear implant array’s precise position is important because of the correlation between electrode position and speech understanding. Several groups have provided recent image processing evidence to determine scalar translocation, angular insertion depth, and cochlear duct length (CDL); all of which are being used for patient-specific programming. Cone beam computed tomography (CBCT) is increasingly used in otology due to its superior resolution and low radiation dose. Our objectives are as followed:
Validate CBCT by measuring cochlear metrics, including basal turn diameter (A-value) and lateral wall cochlear duct length at different angular intervals and comparing it against microcomputed CT (uCT). Explore the relationship between measured lateral wall cochlear duct length at different angular intervals and insertion depth among 3 different length electrodes using CBCT.
Methods The study was performed using fixed human cadaveric temporal bones in a tertiary academic centre. Ten temporal bones were subjected to the standard facial recess approach for cochlear implantation and imaged by CBCT followed by uCT. Measurements were performed on a three-dimensional reconstructed model of the cochlea. Sequential insertion of 3 electrodes (Med-El Flex24, 28 and Soft) was then performed in 5 bones and reimaged by CBCT. Statistical analysis was performed using Pearson’s correlation. Results There was good agreement between CBCT and uCT for cochlear metrics, validating the precision of CBCT against the current gold standard uCT in imaging. The A-value recorded by both modalities showed a high degree of linear correlation and did not differ by more than 0.23 mm in absolute values. For the measurement of lateral wall CDL at various points along the cochlea, there was a good correlation between both modalities at 360 deg and 720 deg (r = 0.85, p < 0.01 and r = 0.79, p < 0.01). The Flex24 electrode displayed consistent insertion depth across different bones. Conclusions CBCT reliably performs cochlear metrics and measures electrode insertion depth. The low radiation dose, fast acquisition time, diminished metallic artifacts and portability of CBCT make it a valid option for imaging in cochlear implant surgery.
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Affiliation(s)
- Kayvan Nateghifard
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Ave., Room M1, Toronto, 102, Canada
| | - David Low
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Ave., Room M1, Toronto, 102, Canada
| | - Lola Awofala
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Ave., Room M1, Toronto, 102, Canada
| | - Dilakshan Srikanthan
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Ave., Room M1, Toronto, 102, Canada
| | - Jafri Kuthubutheen
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Ave., Room M1, Toronto, 102, Canada.,University of Western Australia, School of Surgery, Perth, Australia
| | - Michael Daly
- Guided Therapeutics (GTx) Program, TECHNA Research Institute, University of Toronto, University Health Network, Toronto, Canada
| | - Harley Chan
- Guided Therapeutics (GTx) Program, TECHNA Research Institute, University of Toronto, University Health Network, Toronto, Canada
| | - Jonathan Irish
- Guided Therapeutics (GTx) Program, TECHNA Research Institute, University of Toronto, University Health Network, Toronto, Canada.,Department of Otolaryngology-Head and Neck Surgery/Surgical Oncology, Princess Margaret Cancer Centre/University Health Network, Toronto, Canada
| | - Joseph Chen
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Ave., Room M1, Toronto, 102, Canada
| | - Vincent Lin
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Ave., Room M1, Toronto, 102, Canada
| | - Trung Ngoc Le
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, University of Toronto, 2075 Bayview Ave., Room M1, Toronto, 102, Canada.
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