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Spahn B, Ilgen L, Neun T, Müller-Graff FT, Schendzielorz P, Hagen R, Althoff D, Zabler S, Rak K. Dependence of Cochlear Duct Length Measurement on the Resolution of the Imaging Dataset. Otol Neurotol 2024; 45:e234-e240. [PMID: 38238926 DOI: 10.1097/mao.0000000000004088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/17/2024]
Abstract
HYPOTHESIS Measurements of the cochlear duct length (CDL) are dependent on the resolution of the imaging dataset. BACKGROUND Previous research has shown highly precise cochlear measurements using 3D-curved multiplanar reconstruction (MPR) and flat-panel volume computed tomography (fpVCT). Thus far, however, there has been no systematic evaluation of the imaging dataset resolution required for optimal CDL measurement. Therefore, the aim of this study was to evaluate the dependence of CDL measurement on the resolution of the imaging dataset to establish a benchmark for future CDL measurements. METHODS fpVCT scans of 10 human petrous bone specimens were performed. CDL was measured using 3D-curved MPR with secondary reconstruction of the fpVCT scans (fpVCT SECO ) and increasing resolution from 466 to 99 μm. In addition, intraobserver variability was evaluated. A best-fit function for calculation of the CDL was developed to provide a valid tool when there are no measurements done with high-resolution imaging datasets. RESULTS Comparison of different imaging resolution settings showed significant differences for CDL measurement in most of the tested groups ( p < 0.05), except for the two groups with the highest resolution. Imaging datasets with a resolution lower than 200 μm showed lower intraobserver variability than the other resolution settings, although there were no clinically unacceptable errors with respect to the Bland-Altman plots. The developed best-fit function showed high accuracy for CDL calculation using resolution imaging datasets of 300 μm or lower. CONCLUSION 3D-curved MPR in fpVCT with a resolution of the imaging dataset of 200 μm or higher revealed the most precise CDL measurement. There was no benefit of using a resolution higher than 200 μm with regard to the accuracy of the CDL measurement.
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Affiliation(s)
- Bjoern Spahn
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center
| | - Lukas Ilgen
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center
| | - Tilmann Neun
- Institute for Diagnostic and Interventional Neuroradiology, University of Wuerzburg
| | - Franz-Tassilo Müller-Graff
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center
| | - Philipp Schendzielorz
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center
| | - Rudolf Hagen
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center
| | - Daniel Althoff
- Fraunhofer Development Center for X-ray Technology, Wuerzburg
| | - Simon Zabler
- Deggendorf Institute of Technology, Faculty of Applied Computer Science, Deggendorf, Germany
| | - Kristen Rak
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center
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Grzybowski M, Malfeld K, Lenarz T, Scheper V, Schurzig D. Optimization of pharmacological interventions in the guinea pig animal model-a new approach to calculate the perilymph volume of the scala tympani. Front Neurosci 2023; 17:1297046. [PMID: 38161797 PMCID: PMC10754993 DOI: 10.3389/fnins.2023.1297046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 11/29/2023] [Indexed: 01/03/2024] Open
Abstract
Objective The guinea pig serves as a well-established animal model for inner ear research, offering valuable insights into the anatomy, physiology, and therapeutic interventions of the auditory system. However, the heterogeneity of results observed in both in-vivo experiments and clinical studies poses challenges in understanding and optimizing pharmacotherapy outcomes. This heterogeneity may be due to individual differences in the size of the guinea pig cochlea and thus in the volume of the scala tympani (ST), which can lead to different drug concentrations in the ST, a fact that has been largely overlooked thus far. To address this issue, we aimed to develop an approach for calculating the individual volume of perilymph within the ST before and after cochlear implant insertion. Method In this study, high-resolution μCT images of a total of n = 42 guinea pig temporal bones were used to determine the volume of the ST. We compared fresh, frozen, and fixed tissues from both colored and albino strains to evaluate the potential influence of tissue condition and strain on the results. Results Our findings demonstrate a variability in mean ST volume with a relative standard deviation (RSD) of 14.7%, comparable to studies conducted with humans (range RSD: 5 to 20%). This indicates that the guinea pig cochlea exhibits similar variability to that of the human cochlea. Consequently, it is crucial to consider this variability when designing and conducting studies utilizing the guinea pig as an animal model. Furthermore, we successfully developed a tool capable of estimating ST volume without the need for manual segmentation, employing two geometric parameters, basal diameter (A) and width (B) of the cochlea, corresponding to the cochlear footprint. The tool is available for free download and use on our website. Conclusion This novel approach provides researchers with a valuable tool to calculate individual ST volume in guinea pigs, enabling more precise dosing strategies and optimization of drug concentrations for pharmacotherapy studies. Moreover, our study underscores the importance of acknowledging and accounting for inter-individual variability in animal models to enhance the translational relevance and applicability of research outcomes in the field of inner ear investigations.
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Affiliation(s)
- Marleen Grzybowski
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- German Hearing Center Hannover, Hannover Medical School, Hannover, Germany
| | - Kathrin Malfeld
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- Center for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- German Hearing Center Hannover, Hannover Medical School, Hannover, Germany
- Center for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
| | - Verena Scheper
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- Center for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
| | - Daniel Schurzig
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- MED-EL Research Center, Hannover, Germany
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Müller-Graff FT, Voelker J, Kurz A, Hagen R, Neun T, Rak K. Accuracy of radiological prediction of electrode position with otological planning software and implications of high-resolution imaging. Cochlear Implants Int 2023; 24:144-154. [PMID: 36617441 DOI: 10.1080/14670100.2022.2159128] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
OBJECTIVES In cochlear implantation, preoperative prediction of electrode position has recently gained increasing attention. Currently, planning is usually done by multislice CT (MSCT). However, flat-panel volume CT (fpVCT) and its secondary reconstructions (fpVCTSECO) allow for more precise visualization of the cochlea. Combined with a newly developed otological planning software, the position of every single contact can be effectively predicted. In this study it was investigated how accurately radiological prediction forecasts the postoperative electrode localization and whether higher image resolution is advantageous. METHODS Utilizing otological planning software (OTOPLAN®) and different clinical imaging modalities (MSCT, fpVCT and fpVCTSECO) the electrode localization [angular insertion depth (AID)] and respective contact frequencies were predicted preoperatively and examined postoperatively. Furthermore, inter-electrode-distance (IED) and inter-electrode-frequency difference (IEFD) were evaluated postoperatively. RESULTS Measurements revealed a preoperative overestimation of AID. Corresponding frequencies were also miscalculated. Determination of IED and IEFD revealed discrepancies at the transition from the basal to the middle turn and round window to the basal turn. All predictions and discrepancies were lowest when using fpVCTSECO. CONCLUSION The postoperative electrode position can be predicted quite accurately using otological planning software. However, because of several potential misjudgments, high-resolution imaging, such as offered by fpVCTSECO, should be used pre- and postoperatively.
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Affiliation(s)
- Franz-Tassilo Müller-Graff
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Wuerzburg, Wuerzburg, Germany
| | - Johannes Voelker
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Wuerzburg, Wuerzburg, Germany
| | - Anja Kurz
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Wuerzburg, Wuerzburg, Germany
| | - Rudolf Hagen
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Wuerzburg, Wuerzburg, Germany
| | - Tilmann Neun
- Institute for Diagnostic and Interventional Neuroradiology, University of Wuerzburg, Wuerzburg, Germany
| | - Kristen Rak
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery and the Comprehensive Hearing Center, University of Wuerzburg, Wuerzburg, Germany
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Mntungwa N, Human-Baron R, Hanekom T. Morphology of the internal auditory canal: Deriving parameters from computer tomography scans. An observational STROBE-MR study. EAR, NOSE & THROAT JOURNAL 2022:1455613221116196. [PMID: 35968806 DOI: 10.1177/01455613221116196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2023] Open
Abstract
OBJECTIVES The objective of this study is to identify and define landmarks to adequately describe the internal auditory canal for inclusion in three-dimensional computational models of the cochlea and its surrounding structures. PARTICIPANTS Computer tomography scans of live human cochleae were collected in the retrospective period. Descriptive and comparative statistics were used to describe the data obtained from the scans. RESULTS The mean anterior-posterior (AP) diameter at the base of the basal turn, the diameter of the AP at the midpoint of the IAC, and the anterior and posterior length of the internal acoustic canal were measured. 57.14% of the internal acoustic canals observed presented with a cylindrical, 40.48% was funnel-shaped and 2.38 % were bud-shaped. A statistically significant differences were found between the diameters of male and female internal acoustic meatus. CONCLUSIONS This paper serves as a reference that provides a set of references for the description of the internal acoustic canal for inclusion in three-dimensional computational reconstruction of the cochlea and surrounding structures.
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Affiliation(s)
- Nandipha Mntungwa
- Department of Anatomy, Faculty of Health Sciences, School of Medicine, University of Pretoria, Pretoria, South Africa
| | - Rene Human-Baron
- Department of Anatomy, Faculty of Health Sciences, School of Medicine, University of Pretoria, Pretoria, South Africa
| | - Tania Hanekom
- Department of Electric, Electronic and Computer Engineering, Faculty of Engineering, Built Environment and Information Technology, University of Pretoria, Pretoria, South Africa
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Variations in microanatomy of the human modiolus require individualized cochlear implantation. Sci Rep 2022; 12:5047. [PMID: 35322066 PMCID: PMC8943032 DOI: 10.1038/s41598-022-08731-x] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2021] [Accepted: 03/10/2022] [Indexed: 11/09/2022] Open
Abstract
Cochlear variability is of key importance for the clinical use of cochlear implants, the most successful neuroprosthetic device that is surgically placed into the cochlear scala tympani. Despite extensive literature on human cochlear variability, few information is available on the variability of the modiolar wall. In the present study, we analyzed 108 corrosion casts, 95 clinical cone beam computer tomographies (CTs) and 15 µCTs of human cochleae and observed modiolar variability of similar and larger extent than the lateral wall variability. Lateral wall measures correlated with modiolar wall measures significantly. ~ 49% of the variability had a common cause. Based on these data we developed a model of the modiolar wall variations and related the model to the design of cochlear implants aimed for perimodiolar locations. The data demonstrate that both the insertion limits relevant for lateral wall damage (approximate range of 4–9 mm) as well as the dimensions required for optimal perimodiolar placement of the electrode (the point of release from the straightener; approximate range of 2–5mm) are highly interindividually variable. The data demonstrate that tip fold-overs of preformed implants likely result from the morphology of the modiolus (with radius changing from base to apex), and that optimal cochlear implantation of perimodiolar arrays cannot be guaranteed without an individualized surgical technique.
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Geraldine Zuniga M, Lenarz T, Rau TS. Hydraulic insertions of cochlear implant electrode arrays into the human cadaver cochlea: preliminary findings. Eur Arch Otorhinolaryngol 2021; 279:2827-2835. [PMID: 34390390 PMCID: PMC9072458 DOI: 10.1007/s00405-021-06979-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 07/02/2021] [Indexed: 11/29/2022]
Abstract
OBJECTIVES (1) To evaluate the feasibility of a non-invasive, novel, simple insertion tool to perform automated, slow insertions of cochlear implant electrode arrays (EA) into a human cadaver cochlea; (2) to estimate the handling time required by our tool. METHODS Basic science study conducted in an experimental OR. Two previously anonymized human cadaver heads, three commercially available EAs, and our novel insertion tool were used for the experiments. Our tool operates as a hydraulic actuator that delivers an EA at continuous velocities slower than manually feasible. INTERVENTION(S) the human cadaver heads were prepared with a round-window approach for CI surgery in a standard fashion. Twelve EA insertion trials using our tool involved: non-invasive fixation of the tool to the head; directing the tool to the round window and EA mounting onto the tool; automated EA insertion at approximately 0.1 mm/s driven by hydraulic actuation. Outcome measurement(s): handling time of the tool; post-insertion cone-beam CT scans to provide intracochlear evaluation of the EA insertions. RESULTS Our insertion tool successfully inserted an EA into the human cadaver cochlea (n = 12) while being attached to the human cadaver head in a non-invasive fashion. Median time to set up the tool was 8.8 (7.2-9.4) min. CONCLUSION The first insertions into the human cochlea using our novel, simple insertion tool were successful without the need for invasive fixation. The tool requires < 10 min to set up, which is clinically acceptable. Future assessment of intracochlear trauma is needed to support its safety profile for clinical translation.
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Affiliation(s)
- M Geraldine Zuniga
- Department of Otolaryngology and Cluster of Excellence Hearing4all, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany.
| | - Thomas Lenarz
- Department of Otolaryngology and Cluster of Excellence Hearing4all, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
| | - Thomas S Rau
- Department of Otolaryngology and Cluster of Excellence Hearing4all, Hannover Medical School, Carl-Neuberg-Str. 1, 30625, Hannover, Germany
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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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Taeger J, Müller-Graff FT, Neun T, Köping M, Schendzielorz P, Hagen R, Rak K. Highly precise navigation at the lateral skull base by the combination of flat-panel volume CT and electromagnetic navigation. Sci Prog 2021; 104:368504211032090. [PMID: 34397283 PMCID: PMC10450718 DOI: 10.1177/00368504211032090] [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] [Indexed: 11/17/2022]
Abstract
This study aimed to evaluate the feasibility and accuracy of electromagnetic navigation at the lateral skull base in combination with flat panel volume computed tomography (fpVCT) datasets. A mastoidectomy and a posterior tympanotomy were performed on 10 samples of fresh frozen temporal bones. For registration, four self-drilling titanium screws were applied as fiducial markers. Multi-slice computed tomography (MSCT; 600 µm), conventional flat panel volume computed tomography (fpVCT; 466 µm), micro-fpVCT (197 µm) and secondary reconstructed fpVCT (100 µM) scans were performed and data were loaded into the navigation system. The resulting fiducial registration error (FRE) was analysed, and control of the navigation accuracy was performed. The registration process was very quick and reliable with the screws as fiducials. Compared to using the MSCT data, the micro-fpVCT data led to significantly lower FRE values, whereas conventional fpVCT and secondary reconstructed fpVCT data had no advantage in terms of accuracy. For all imaging modalities, there was no relevant visual deviation when targeting defined anatomical points with a navigation probe. fpVCT data are very well suited for electromagnetic navigation at the lateral skull base. The use of titanium screws as fiducial markers turned out to be ideal for comparing different imaging methods. A further evaluation of this approach by a clinical trial is required.
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Affiliation(s)
- Johannes Taeger
- Department of Otorhinolaryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University Hospital Würzburg, Würzburg, Bavaria, Germany
| | - Franz-Tassilo Müller-Graff
- Department of Otorhinolaryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University Hospital Würzburg, Würzburg, Bavaria, Germany
| | - Tilmann Neun
- Institute for Diagnostical and Interventional Neuroradiology, University Hospital Würzburg, Würzburg, Bavaria, Germany
| | - Maria Köping
- Department of Otorhinolaryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University Hospital Würzburg, Würzburg, Bavaria, Germany
| | - Philipp Schendzielorz
- Department of Otorhinolaryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University Hospital Würzburg, Würzburg, Bavaria, Germany
| | - Rudolf Hagen
- Department of Otorhinolaryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University Hospital Würzburg, Würzburg, Bavaria, Germany
| | - Kristen Rak
- Department of Otorhinolaryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University Hospital Würzburg, Würzburg, Bavaria, Germany
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On the Intracochlear Location of Straight Electrode Arrays After Cochlear Implantation: How Lateral Are Lateral Wall Electrodes? Otol Neurotol 2021; 42:242-250. [PMID: 33026778 DOI: 10.1097/mao.0000000000002880] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
OBJECTIVE Cochlear implants are the gold standard for patients with severe sensorineural hearing loss. A focused electrical stimulation of individual spiral ganglion neurons has not been achieved yet because the scala tympani is a fluid-filled compartment and does not offer a matrix for neuritic outgrowth. Coating of the electrode contacts with swelling hydrogels could fill that gap between the electrode array and the medial wall of the cochlea. Therefore, the exact position of the electrode array within the scala tympani has to be known. STUDY DESIGN Retrospective analysis of patient data sets. SETTING Tertiary referral center. A total of 95 patients with cochlear implants from one manufacturer were included in this study. The lateral wall, the modiolar wall, and the cochlear implant electrode were segmented using OsiriX MD. For repositioning and reconstructing the respective contours and measuring distances, files were analyzed in MATLAB. The distances from the edge of each electrode contact to the cochlear walls showed no significant differences. But between the different contacts within each patient, there were significant differences. Around 180 degree insertion, electrodes start to get in contact with the lateral wall. The tip of the electrode array was always facing toward the modiolar wall independent of the length of the electrode. We established a method to analyze the position of electrodes within the cochlea.
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Schurzig D, Fröhlich M, Raggl S, Scheper V, Lenarz T, Rau TS. Uncoiling the Human Cochlea-Physical Scala Tympani Models to Study Pharmacokinetics Inside the Inner Ear. Life (Basel) 2021; 11:life11050373. [PMID: 33919445 PMCID: PMC8143569 DOI: 10.3390/life11050373] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 04/15/2021] [Accepted: 04/20/2021] [Indexed: 11/16/2022] Open
Abstract
In the field of cochlear implantation, artificial/physical models of the inner ear are often employed to investigate certain phenomena like the forces occurring during implant insertions. Up to now, no such models are available for the analysis of diffusion processes inside the cochlea although drug delivery is playing an increasingly important role in this field. For easy access of the cochlea along its whole profile, e.g., for sequential sampling in an experimental setting, such a model should ideally be longitudinal/uncoiled. Within this study, a set of 15 micro-CT imaging datasets of human cochleae was used to derive an average representation of the scala tympani. The spiral profile of this model was then uncoiled along different trajectories, showing that these trajectories influence both length and volume of the resulting longitudinal model. A volumetric analysis of the average spiral model was conducted to derive volume-to-length interrelations for the different trajectories, which were then used to generate two tubular, longitudinal scala tympani models with volume and length properties matching the original, spiral profile. These models can be downloaded for free and used for reproducible and comparable simulative and experimental investigations of diffusion processes within the inner ear.
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Affiliation(s)
- Daniel Schurzig
- MED-EL Research Center, 30625 Hannover, Germany;
- Department of Otolaryngology, Hannover Medical School, 30625 Hannover, Germany; (V.S.); (T.L.); (T.S.R.)
- Correspondence: ; Tel.: +49-511-1659-4795
| | - Max Fröhlich
- MED-EL Research Center, 30625 Hannover, Germany;
- Department of Otolaryngology, Hannover Medical School, 30625 Hannover, Germany; (V.S.); (T.L.); (T.S.R.)
| | - Stefan Raggl
- MED-EL Medical Electronics, 6020 Innsbruck, Austria;
| | - Verena Scheper
- Department of Otolaryngology, Hannover Medical School, 30625 Hannover, Germany; (V.S.); (T.L.); (T.S.R.)
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, 30625 Hannover, Germany; (V.S.); (T.L.); (T.S.R.)
| | - Thomas S. Rau
- Department of Otolaryngology, Hannover Medical School, 30625 Hannover, Germany; (V.S.); (T.L.); (T.S.R.)
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Precise Evaluation of the Cochlear Duct Length by Flat-panel Volume Computed Tomography (fpVCT)-Implication of Secondary Reconstructions. Otol Neurotol 2021; 42:e294-e303. [PMID: 33555750 DOI: 10.1097/mao.0000000000002951] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
HYPOTHESIS Flat-panel volume computed tomography (fpVCT) and secondary reconstruction allow for more accurate measurements of two-turn length (2TL), cochlear duct length (CDL), and angular length (AL). BACKGROUND Cochlear geometry is a controversially debated topic. In the meantime, there are many different studies partly reporting highly divergent values. Our aim is to discuss the differences and to propose a radiological possibility to improve cochlear measurements using 3D-curved multiplanar reconstruction and fpVCT. METHODS Performing different image modalities and settings, we tried to find a clinically usable option that allows for a high degree of accuracy. Therefore, we tested them against reference values of high-definition micro-computed tomography. RESULTS Comparison of 99 μm slice thickness secondary reconstruction of fpVCT and reference showed no significant differences for 2TL and CDL (p ≥ 0.05). Accordingly, ICC (intraclass correlation) values were excellent (ICC ≥ 0.75; lower limit of confidence interval [CI] ≥ 0.75; Cronbach's alpha [α] ≥ 0.9). Evaluating AL, there was a significant difference (difference: -17.27°; p = 0.002). The lower limit of the CI of the ICC was unacceptable (ICC = 0.944; lower limit of CI = 0.248; α = 0.990). Regarding the Bland-Altman plots, there were no clinically unacceptable errors, but a systematic underestimation of AL. CONCLUSION Secondary reconstruction is a suitable tool for producing reliable data that allow the accurate measurement of 2TL and CDL. The option of generating these reconstructions from raw data limits the need for higher radiation doses. Nevertheless, there is an underestimation of AL using secondary reconstructions.
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Abstract
OBJECTIVE The intracochlear position of an electrode array may influence the outcome after cochlear implantation. The design of the electrode array can increase the risk of trauma causing penetration of the basilar membrane or shift of the electrode array into the scala vestibuli. The aim of the present study was to identify a scalar shift after implantation of two different electrode arrays developed by one manufacturer. STUDY DESIGN Retrospective analysis. SETTING Tertiary referral center. PATIENTS AND INTERVENTION Cochlear implant recipients implanted between 2010 and 2014 and receiving either a mid-scala (n = 30) or a perimodiolar (n = 30) electrode array. MAIN OUTCOME MEASURE Occurrence of scalar shift in association with the electrode type. RESULTS Scalar shift occurred in 26.7% (8 of 30) of the patients implanted with a perimodiolar electrode array and in 6.7% (2 of 30) of the patients implanted with the mid-scala electrode array. The mean insertion depth in the patients experiencing scalar shift after implantation of the mid-scala electrode was much deeper (21.59 ± 0.34 mm) when compared with the mean insertion depth of the patients with scalar shift after implantation with a perimodiolar electrode array (17.85 ± 2.19 mm). There tends to be a correlation between the cochlear length and the occurrence of a scalar shift. However, the number of patients with scalar shift in the mid-scala group is rather small. CONCLUSION Based on the presented data, more patients implanted with a perimodiolar electrode array have a scalar shift when compared with the midscalar electrode array.
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Effect of Electrode to Modiolus Distance on Electrophysiological and Psychophysical Parameters in CI Patients With Perimodiolar and Lateral Electrode Arrays. Otol Neurotol 2020; 41:e1091-e1097. [DOI: 10.1097/mao.0000000000002751] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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14
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Wang Z, Li J, Wu Y, Zhu R, Wang B, Zhao K. Optimal path generation in scala tympani and path planning for robotic cochlear implant of perimodiolar electrode. Proc Inst Mech Eng H 2020; 234:578-589. [PMID: 32186227 DOI: 10.1177/0954411920908969] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
In this study, a new idea of the optimal path generation method was proposed and a path planning strategy for robotic cochlear implant of perimodiolar electrode was designed. The centerline of scala tympani channel was taken as the optimal implant path of the perimodiolar electrode, which aimed to reduce the damage of the electrode to the cochlea during implantation. First, the three-dimensional cochlear model was reconstructed based on the micro-computed tomography images of cochlea, and it was re-segmented to obtain the cross sections of the scala tympani at different angles. Then, the image processing method was used to determine the central point of the scala tympani cross sections. The cubic B-spline interpolation method was used to fit these discrete central points to generate the optimal path. Finally, the coordinate information of the optimal path was combined with the stylet extraction state of perimodiolar electrode to conduct the path planning for robotic cochlear implant, and the result was sent to the robot for kinematic inverse solution to obtain the robot motion trajectory. The robotic cochlear implant experiment was performed with the model of scala tympani. The results showed that the maximum implant force based on path planning was 0.084 N, and the maximum implant force without path planning was 0.134 N. The optimal path generation and the path planning method effectively help to reduce the damage of the electrode to the cochlea.
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Affiliation(s)
- Zuo Wang
- China Jiliang University, Hangzhou, China
| | - Jianjun Li
- China Jiliang University, Hangzhou, China
| | - Yongzhen Wu
- EYE & ENT Hospital of Fudan University, Shanghai, China
| | | | | | - Kai Zhao
- China Jiliang University, Hangzhou, China
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Timm ME, Majdani O, Weller T, Windeler M, Lenarz T, Büchner A, Salcher RB. Patient specific selection of lateral wall cochlear implant electrodes based on anatomical indication ranges. PLoS One 2018; 13:e0206435. [PMID: 30365565 PMCID: PMC6203394 DOI: 10.1371/journal.pone.0206435] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Accepted: 10/12/2018] [Indexed: 11/19/2022] Open
Abstract
OBJECTIVES The aim of this study was to identify anatomical indication ranges for different lateral wall cochlear implant electrodes to support surgeons in the preoperative preparation. METHODS 272 patients who were implanted with a FLEX20, FLEX24, FLEX28, or a custom-made device (CMD) were included in this study. The cochlear duct length (CDL) and basal cochlear diameter (length A) were measured within preoperative imaging data. The parameter A was then employed to additionally compute CDL estimates using literature approaches. Moreover, the inserted electrode length (IEL) and insertion angle (IA) were measured in postoperative CT data. By combining the preoperative measurements with the IA data, the covered cochlea length (CCL) and relative cochlear coverage (CC) were determined for each cochlea. RESULTS The measurements of the CDL show comparable results to previous studies. While CDL measurements and estimations cover similar ranges overall, severe deviations occur in individual cases. The electrode specific IEL and CCL are fairly consistent and increase with longer electrodes, but relatively wide ranges of electrode specific CC values were found due to the additional dependence on the respective CDL. Using the correlation of IEL and CCL across electrode arrays, CDL ranges for selected arrays were developed (FLEX24: 31.3-34.4, FLEX28: 36.2-40.1, FLEXSoft: 40.6-44.9). CONCLUSIONS Our analysis shows that electrode specific CC varies due to the CDL variation. Preoperative measurement of the CDL allows for an individualized implant length selection yielding optimized stimulation and a reduced risk of intraoperative trauma. The CDL, as derived from preoperative CT imaging studies, can help the implant surgeon select the appropriate electrode array to maximize the patient's outcomes.
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Affiliation(s)
- Max Eike Timm
- Cluster of Excellence Hearing4all, Department of Otorhinolaryngology, Hannover Medical School, Hannover, Lower Saxony, Germany
- * E-mail:
| | - Omid Majdani
- Cluster of Excellence Hearing4all, Department of Otorhinolaryngology, Hannover Medical School, Hannover, Lower Saxony, Germany
| | - Tobias Weller
- Cluster of Excellence Hearing4all, Department of Otorhinolaryngology, Hannover Medical School, Hannover, Lower Saxony, Germany
| | - Mayra Windeler
- Cluster of Excellence Hearing4all, Department of Otorhinolaryngology, Hannover Medical School, Hannover, Lower Saxony, Germany
| | - Thomas Lenarz
- Cluster of Excellence Hearing4all, Department of Otorhinolaryngology, Hannover Medical School, Hannover, Lower Saxony, Germany
| | - Andreas Büchner
- Cluster of Excellence Hearing4all, Department of Otorhinolaryngology, Hannover Medical School, Hannover, Lower Saxony, Germany
| | - Rolf Benedikt Salcher
- Cluster of Excellence Hearing4all, Department of Otorhinolaryngology, Hannover Medical School, Hannover, Lower Saxony, Germany
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Schurzig D, Timm ME, Batsoulis C, Salcher R, Sieber D, Jolly C, Lenarz T, Zoka-Assadi M. A Novel Method for Clinical Cochlear Duct Length Estimation toward Patient-Specific Cochlear Implant Selection. OTO Open 2018; 2:2473974X18800238. [PMID: 30719505 PMCID: PMC6348517 DOI: 10.1177/2473974x18800238] [Citation(s) in RCA: 75] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2018] [Revised: 06/12/2018] [Accepted: 08/22/2018] [Indexed: 11/21/2022] Open
Abstract
Objective In the field of cochlear implantation, the current trend toward patient-specific electrode selection and the achievement of optimal audiologic outcomes has resulted in implant manufacturers developing a large portfolio of electrodes. The aim of this study was to bridge the gap between the known variability of cochlea length and this electrode portfolio. Design Retrospective analysis on cochlear length and shape in micro–computed tomography and cone beam computed tomography data. Setting Tertiary care medical center. Subjects and Methods A simple 2-step approach was developed to accurately estimate the individual cochlear length as well as the projected length of an electrode array inside the cochlea. The method is capable of predicting the length of the cochlea and the inserted electrode length at any specific angle. Validation of the approach was performed with 20 scans of human temporal bones (micro–computed tomography) and 47 pre- and postoperative clinical scans (cone beam computed tomography). Results Mean ± SD absolute errors in cochlear length estimations were 0.12 ± 0.10 mm, 0.38 ± 0.26 mm, and 0.71 ± 0.43 mm for 1, 1.5, and 2 cochlea turns, respectively. Predicted insertion angles based on clinical cone beam computed tomography data showed absolute deviations of 27° ± 18° to the corresponding postoperative measurements. Conclusion With accuracy improvements of 80% to 90% in comparison with previously proposed approaches, the method is well suited for the use in individualized cochlear implantation.
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Affiliation(s)
- Daniel Schurzig
- MED-EL Medical Electronics, Hannover Research Center, Hannover, Germany
| | - Max Eike Timm
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | | | - Rolf Salcher
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Daniel Sieber
- MED-EL Medical Electronics, Hannover Research Center, Hannover, Germany
| | - Claude Jolly
- MED-EL Medical Electronics, Hannover Research Center, Hannover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany.,Cluster of Excellence Hearing4all, Hannover Medical School, Hannover, Germany
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Schurzig D, Timm ME, Lexow GJ, Majdani O, Lenarz T, Rau TS. Cochlear helix and duct length identification – Evaluation of different curve fitting techniques. Cochlear Implants Int 2018; 19:268-283. [DOI: 10.1080/14670100.2018.1460025] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Affiliation(s)
- Daniel Schurzig
- MED-EL Medical Electronics, Hannover Research Center, Hannover, Germany
| | - Max Eike Timm
- Cluster of Excellence Hearing4all, Dept. of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - G. Jakob Lexow
- Cluster of Excellence Hearing4all, Dept. of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Omid Majdani
- Cluster of Excellence Hearing4all, Dept. of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Cluster of Excellence Hearing4all, Dept. of Otolaryngology, Hannover Medical School, Hannover, Germany
| | - Thomas S. Rau
- Cluster of Excellence Hearing4all, Dept. of Otolaryngology, Hannover Medical School, Hannover, Germany
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Lexow GJ, Kluge M, Gellrich NC, Lenarz T, Majdani O, Rau TS. On the accuracy of cochlear duct length measurement in computed tomographic images. Eur Arch Otorhinolaryngol 2018. [DOI: 10.1007/s00405-018-4930-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Evaluation of Cochlear Duct Length Computations Using Synchrotron Radiation Phase-Contrast Imaging. Otol Neurotol 2017; 38:e92-e99. [DOI: 10.1097/mao.0000000000001410] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Insertion forces and intracochlear trauma in temporal bone specimens implanted with a straight atraumatic electrode array. Eur Arch Otorhinolaryngol 2017; 274:2131-2140. [PMID: 28238160 DOI: 10.1007/s00405-017-4485-z] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 01/25/2017] [Indexed: 10/20/2022]
Abstract
The aim of the study was to evaluate insertion forces during manual insertion of a straight atraumatic electrode in human temporal bones, and post-implantation histologic evaluation of the samples to determine whether violation of intracochlear structures is related to insertion forces. In order to minimize intracochlear trauma and preserve residual hearing during cochlear implantation, knowledge of the insertion forces is necessary. Ten fresh frozen human temporal bones were prepared with canal wall down mastoidectomy. All samples were mounted on a one-axis force sensor. Insertion of a 16-mm straight atraumatic electrode was performed from different angles to induce "traumatic" insertion. Histologic evaluation was performed in order to evaluate intracochlear trauma. In 4 of 10 samples, dislocation of the electrode into scala vestibuli was observed. The mean insertion force for all 10 procedures was 0.003 ± 0.005 N. Insertion forces measured around the site of dislocation to scala vestibuli in 3 of 4 samples were significantly higher than insertion forces at the same location of the cochleae measured in samples without trauma (p < 0.04). Mean force during the whole insertion process of the straight atraumatic electrode is lower than reported by other studies using longer electrodes. Based on our study, insertion forces leading to basilar membrane trauma may be lower than the previously reported direct rupture forces.
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Schurzig D, Lexow GJ, Majdani O, Lenarz T, Rau TS. Three-dimensional modeling of the cochlea by use of an arc fitting approach. Comput Methods Biomech Biomed Engin 2016; 19:1785-1799. [DOI: 10.1080/10255842.2016.1188921] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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