How to predict cochlear length before cochlear implantation surgery

Erixon, Elsa; Rask‐Andersen, Helge

doi:10.3109/00016489.2013.831475

Cited by 83 publications

(84 citation statements)

References 18 publications

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“…This study still used the indirect approach, but instead of preparing serial histologic sections, consistent photographs were taken from above the plastic casted cochleae, and the 2D reconstruction was done from the images. Erixon performed another study on different plastic casts in 2013 finding very similar results as the previous study [41]. The 51 samples used had a mean length of the LW of 41.2mm and a range of 37.6mm to 44.9mm.…”

Section: Methods Of Measuring CDLsupporting

confidence: 73%

“…They extracted the cochlea from cadaveric specimens and stained and hardened them into plastic casts [3, 41]. Erixon et al then used an indirect approach to measure the length of the LW.…”

Section: Discussionmentioning

confidence: 99%

“…The length of the cochlea has been evaluated by: a direct method; measuring the length from histologic sections by a micrometer under a microscope [4, 7, 33–36], an indirect method; graphically representing the cochlea by using landmarks from histologic sections or plastic casts [3, 4, 37–41], 3D reconstruction; reconstructing the cochlea by placing points on a cochlea and transferring the points to a computer as 3D coordinates [5, 24, 42–44], and by modeling the cochlea as a mathematical spiral function [6, 45–47]. As seen in the timeline in Fig.…”

Section: Methods Of Measuring CDLmentioning

confidence: 99%

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Measuring Cochlear Duct Length – a historical analysis of methods and results

Koch

Ladak

Elfarnawany

et al. 2017

J of Otolaryngol - Head & Neck Surg

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BackgroundCochlear Duct Length (CDL) has been an important measure for the development and advancement of cochlear implants. Emerging literature has shown CDL can be used in preoperative settings to select the proper sized electrode and develop customized frequency maps. In order to improve post-operative outcomes, and develop new electrode technologies, methods of measuring CDL must be validated to allow usage in the clinic.PurposeThe purpose of this review is to assess the various techniques used to calculate CDL and provide the reader with enough information to make an informed decision on how to conduct future studies measuring the CDL.ResultsThe methods to measure CDL, the modality used to capture images, and the location of the measurement have all changed as technology evolved. With recent popularity and advancement in computed tomography (CT) imaging in place of histologic sections, measurements of CDL have been focused at the lateral wall (LW) instead of the organ of Corti (OC), due to the inability of CT to view intracochlear structures. After analyzing results from methods such as directly measuring CDL from histology, indirectly reconstructing the shape of the cochlea, and determining CDL based on spiral coefficients, it was determined the three dimensional (3D) reconstruction method is the most reliable method to measure CDL. 3D reconstruction provides excellent visualization of the cochlea and avoids errors evident in other methods. Due to the number of varying methods with varying accuracies, certain guidelines must be followed in the future to allow direct comparison of CDL values between studies.ConclusionAfter summarizing and analyzing the interesting history of CDL measurements, the use of standardized guidelines and the importance of CDL for future cochlear implant developments is emphasized for future studies.

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Section: Methods Of Measuring CDLsupporting

confidence: 73%

“…They extracted the cochlea from cadaveric specimens and stained and hardened them into plastic casts [3, 41]. Erixon et al then used an indirect approach to measure the length of the LW.…”

Section: Discussionmentioning

confidence: 99%

Section: Methods Of Measuring CDLmentioning

confidence: 99%

See 1 more Smart Citation

Measuring Cochlear Duct Length – a historical analysis of methods and results

Koch

Ladak

Elfarnawany

et al. 2017

J of Otolaryngol - Head & Neck Surg

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“…We expressed the intracochlear electrode array insertion as insertion angle instead of insertion depth, because the size of the cochlea may differ amongst patients [Stakhovskaya et al, 2007;Erixon et al, 2013;Van der Marel et al, 2014] and the intracochlear position of the electrode array may lead to different insertion angles for identical insertion depths.…”

Section: Insertion Angle Of CI Electrode Arraymentioning

confidence: 99%

Comparison of Place-versus-Pitch Mismatch between a Perimodiolar and Lateral Wall Cochlear Implant Electrode Array in Patients with Single-Sided Deafness and a Cochlear Implant

2019

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Background: In electric-acoustic pitch matching experiments in patients with single-sided deafness and a cochlear implant, the observed “mismatch” between perceived pitch and predicted pitch, based on the amended Greenwood frequency map, ranges from –1 to –2 octaves. It is unknown if and how this mismatch differs for perimodiolar versus lateral wall electrode arrays. Objectives: We aimed to investigate if the type of electrode array design is of influence on the electric-acoustic pitch match. Method: Fourteen patients (n = 8 with CI422 + lateral wall electrode array, n = 6 with CI512 + perimodiolar electrode array; Cochlear Ltd.) compared the pitch of acoustic stimuli to the pitch of electric stimuli at two test sessions (average interval 4.3 months). We plotted these “pitch matches” per electrode contact against insertion angle, calculated from high-resolution computed tomography scans. The difference between these pitch matches and two references (the spiral ganglion map and the default frequency allocation by Cochlear Ltd.) was defined as “mismatch.” Results: We found average mismatches of –2.2 octaves for the CI422 group and –1.3 octaves for the CI512 group. For any given electrode contact, the mismatch was smaller for the CI512 electrode array than for the CI422 electrode array. For all electrode contacts together, there was a significant difference between the mismatches of the two groups (p < 0.05). Results remained stable over time, with no significant difference between the two test sessions considering all electrode contacts. Neither group showed a significant correlation between the mismatch and phoneme recognition scores. Conclusion: The pitch mismatch was smaller for the perimodiolar electrode array than for the lateral wall electrode array.

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“…Furthermore, as outlined previously by Brill et al (2009), many studies are limited by the extent to which the length of the cochlea was stimulated and thus, the effect of stimulation at the apex could not be investigated. Firstly, many studies employ electrodes of limited length (Brill et al, 2009), and secondly, the length of the cochlea differs greatly between individuals (Erixon and Rask-Andersen, 2013;Franke-Trieger et al, 2014;Franke-Trieger and Murbe, 2015;Würfel et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

Electrically evoked compound action potentials are different depending on the site of cochlear stimulation

Heyning

Arauz²,

Atlas

et al. 2016

Cochlear Implants International

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One of the many parameters that can affect cochlear implant (CI) users' performance is the site of presentation of electrical stimulation, from the CI, to the auditory nerve. Evoked compound action potential (ECAP) measurements are commonly used to verify nerve function by stimulating one electrode contact in the cochlea and recording the resulting action potentials on the other contacts of the electrode array.The present study aimed to determine if the ECAP amplitude differs between the apical, middle, and basal region of the cochlea, if double peak potentials were more likely in the apex than the basal region of the cochlea, and if there were differences in the ECAP threshold and recovery function across the cochlea.ECAP measurements were performed in the apical, middle, and basal region of the cochlea at fixed sites of stimulation with varying recording electrodes. One hundred and forty one adult subjects with severe to profound sensorineural hearing loss fitted with a Standard or FLEX SOFT electrode were included in this study. ECAP responses were captured using MAESTRO System Software (MED-EL). The ECAP amplitude, threshold, and slope were determined using amplitude growth sequences. The 50% recovery rate was assessed using independent single sequences that have two stimulation pulses (a masker and a probe pulse) separated by a variable inter-pulse interval. For all recordings, ECAP peaks were annotated semi-automatically.ECAP amplitudes were greater upon stimulation of the apical region compared to the basal region of the cochlea. ECAP slopes were steeper in the apical region compared to the basal region of the cochlea and 251 ECAP thresholds were lower in the middle region compared to the basal region of the cochlea. The incidence of double peaks was greater upon stimulation of the apical region compared to the basal region of the cochlea. This data indicates that the site and intensity of cochlear stimulation affect ECAP properties.

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How to predict cochlear length before cochlear implantation surgery

Cited by 83 publications

References 18 publications

Measuring Cochlear Duct Length – a historical analysis of methods and results

Measuring Cochlear Duct Length – a historical analysis of methods and results

Comparison of Place-versus-Pitch Mismatch between a Perimodiolar and Lateral Wall Cochlear Implant Electrode Array in Patients with Single-Sided Deafness and a Cochlear Implant

Electrically evoked compound action potentials are different depending on the site of cochlear stimulation

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