Authors: Guoqiang Sun, Yandong Zheng, Xiaolong Fu...

Progressive functional deterioration in the cochlea is associated with age-related hearing loss (ARHL). However, the cellular and molecular basis underlying cochlear aging remains largely unknown. Here, we established a dynamic single-cell transcriptomic landscape of mouse cochlear aging, in which we characterized aging-associated transcriptomic changes in 27 different cochlear cell types across five different time points. Overall, our analysis pinpoints loss of proteostasis and elevated apoptosis as the hallmark features of cochlear aging, highlights unexpected age-related transcriptional fluctuations in intermediate cells localized in the stria vascularis (SV) and demonstrates that upregulation of endoplasmic reticulum (ER) chaperon protein HSP90AA1 mitigates ER stress-induced damages associated with aging. Our work suggests that targeting unfolded protein response pathways may help alleviate aging-related SV atrophy and hence delay the progression of ARHL.

Topics: Mice; Animals; Transcriptome; Aging; Cochlea; Stria Vascularis; Presbycusis

PubMed: 36933008
DOI: 10.1093/procel/pwac058

Review

Authors: Yuxin Deng, Sen Chen, Jun Hu...

Diabetes mellitus (DM) is a major disease threatening human health and its incidence is increasing year on year. As a chronic complication of DM, hearing loss mostly occurs undetectably. However, the mechanism of this diabetes-related hearing loss (DRHL) remains unclear and there is no effective clinical treatment. Studies of animal or human pathology show that DM causes damage to the blood vessels, spiral ganglion neurons, afferent nerve fibers, the organ of Corti, and the stria vascularis of the inner ear. In recent years, more advances in pathological research have revealed the possible mechanism of DRHL. In addition, a large number of clinical studies suggest that the duration and severity of DM are closely related to the incidence and severity of DRHL. This review focuses on the relationship between DM and hearing loss. The clinical audiological characteristics of diabetic patients, risk factors for DRHL, typical pathology, and potential interventions of DRHL are summarized. This will help reveal the pathogenesis and intervention approaches for DRHL.

Topics: Animals; Humans; Hearing Loss; Diabetes Mellitus; Stria Vascularis; Risk Factors

PubMed: 37875793
DOI: 10.1186/s10020-023-00737-z

Review

Authors: Robert W Koch, Hanif M Ladak, Mai Elfarnawany...

BACKGROUND

Cochlear 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.

PURPOSE

The 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.

RESULTS

The 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.

CONCLUSION

After 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.

Topics: Cochlear Duct; Cochlear Implantation; Cochlear Implants; Female; Follow-Up Studies; Humans; Male; Postoperative Complications; Preoperative Care; Prosthesis Design; Risk Assessment; Tomography, X-Ray Computed; Treatment Outcome

PubMed: 28270200
DOI: 10.1186/s40463-017-0194-2

Authors: M B Eser, B Atalay, M B Dogan...

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.

Topics: Adult; Cochlear Duct; Humans; Imaging, Three-Dimensional; Magnetic Resonance Imaging; Male; Reproducibility of Results; Tomography, X-Ray Computed

PubMed: 34593380
DOI: 10.3174/ajnr.A7287

Authors: Jennifer L Spiegel, Daniel Polterauer, John-Martin Hempel...

PURPOSE

In cochlear implantation, thorough preoperative planning together with measurement of the cochlear duct length (CDL) assists in choosing the correct electrode length. For measuring the CDL, different techniques have been introduced in the past century along with the then available technology. A tablet-based software offers an easy and intuitive way to visualize and analyze the anatomy of the temporal bone, its proportions and measure the CDL. Therefore, we investigated the calculation technique of the CDL via a tablet-based software on our own cohort retrospectively.

METHODS

One hundred and eight preoperative computed tomography scans of the temporal bone (slice thickness < 0.7 mm) of already implanted FLEX28™ and FLEXSOFT™ patients were found eligible for analysis with the OTOPLAN software. Measurements were performed by two trained investigators independently. CDL, angular insertion depth (AID), and cochlear coverage were calculated and compared between groups of electrode types, sex, sides, and age.

RESULTS

Mean CDL was 36.2 ± 1.8 mm with significant differences between sex (female: 35.8 ± 0.3 mm; male: 36.5 ± 0.2 mm; p = 0.037), but none concerning side or age. Differences in mean AID (FLEX28: 525.4 ± 46.4°; FLEXSOFT: 615.4 ± 47.6°), and cochlear coverage (FLEX28: 63.9 ± 5.6%; FLEXSOFT: 75.8 ± 4.3%) were significant (p < 0.001).

CONCLUSION

A broad range of CDL was observed with significant larger values in male, but no significant differences concerning side or age. Almost every cochlea was measured longer than 31.0 mm. Preoperative assessment aids in prevention of complications (incomplete insertion, kinking, tipfoldover), attempt of atraumatic insertion, and addressing individual necessities (hearing preservation, cochlear malformation). The preferred AID of 720° (two turns of the cochlea) was never reached, opening the discussion for the requirement of longer CI-electrodes versus a debatable audiological benefit for the patient in his/her everyday life.

Topics: Cochlea; Cochlear Duct; Cochlear Implantation; Cochlear Implants; Female; Humans; Male; Retrospective Studies; Software; Temporal Bone

PubMed: 34050805
DOI: 10.1007/s00405-021-06889-0

Authors: Anandhan Dhanasingh

BACKGROUND AND OBJECTIVE

The size of the cochlea varies a lot among the human population bringing the necessity for electrode arrays to be available in various lengths irrespective of the cochlear implant (CI) brand. This research software helps in the estimation of the patient's cochlear duct length (CDL) which is then used for the simulation of the correct length electrode array matching the patient's cochlear size and as well in getting the patient specific cochlear frequency map.

METHODS

Visual Studio Express 2012 for Windows Desktop is used in the architecture of this research software. The basal turn diameter of the cochlea ("A" value) needs to be measured from the pre-operative computed tomography (CT) image of the patient's temporal bone. This "A" will be taken as the input for the CDL equations proposed by Alexiades et al for estimating the CDL along the basilar membrane for various insertion depths. Greenwood's equation is then used in combination with the CDL for the full length of the cochlea in getting the patient specific frequency map.

RESULTS

The research software with the help of the "A" value as input, with few button clicks, gives the patient specific CDL for various insertion depths and the Greenwood's frequency map. The users have the choice to select any electrode array of their choice and place it under the frequency map to see how good it fits to that particular patient's cochlea. Also, given the possibility to drag and move the electrode array picture to mimic the post-operative actual electrode insertion depth.

CONCLUSIONS

This research software simplifies the overall process of CDL estimation and in getting the patient specific cochlear frequency map. The clinicians get the chance to simulate placing the various electrode array lengths in patient cochlea in identifying the best fit electrode. This could help in pushing the CI field into the concept of individualized CI electrode array solution that ultimately benefits the patients.

PubMed: 33474539
DOI: 10.1016/j.wjorl.2018.12.002

Authors: Almir Salkic, Erdem Yildiz, Wolf-Dieter Baumgartner...

PURPOSE

The objective of the study was to evaluate the proposed cochlear duct length estimation based on the cochlear 'A value'. Furthermore, we assessed the interobserver variability between radiology and otolaryngology attending physicians and otolaryngology trainees.

METHODS

Thirteen pediatric cochlear implant candidates were retrospectively analyzed by three otolaryngology physicians (attending physician, second year, and fourth year trainees) and a radiology attending. The cochlear duct length was calculated based on the formula of Grover et al. The differences in acquired measurements between observers were compared using the Wilcoxon matched signed-rank test.

RESULTS

The differences in measurements between the attending otolaryngologist and radiologist were not statistically different, while several significant differences were observed with regard to measurements of attending doctors compared to both residents. In particular, a significant difference between the second year otolaryngology resident and otolaryngology and radiology attending was observed for one side (right ear p = 0.034 and p = 0.012, respectively). Moreover, the fourth year resident calculated significantly different cochlear duct measurements when compared to the attending otolaryngologist (left ear p = 0.014) and radiologist (right ear p = 0.047). Interestingly, differently experienced otolaryngology residents provided significantly different measurements for both ears.

CONCLUSIONS

Based on these results, cochlear duct length measurement according to the proposed method may be a reliable and cost-effective method. Indeed, otolaryngology training may be sufficient to provide measurements comparable to radiologists. On the other hand, additional efforts should be invested during otolaryngology training in terms of the evaluation of radiological imaging which may increase the capabilities of otolaryngology residents in this regard.

Topics: Humans; Child; Cochlear Implants; Observer Variation; Retrospective Studies; Cochlear Implantation; Cochlear Duct

PubMed: 36074160
DOI: 10.1007/s00405-022-07639-6

Authors: Johannes Taeger, Franz Tassilo Müller-Graff, Lukas Ilgen...

OBJECTIVE

Growing interest in measuring the cochlear duct length (CDL) has emerged, since it can influence the selection of cochlear implant electrodes. Currently the measurements are performed with ionized radiation imaging. Only a few studies have explored CDL measurements in magnetic resonance imaging (MRI). Therefore, the presented study aims to fill this gap by estimating CDL in MRI and comparing it with multislice computed tomography (CT).

STUDY DESIGN

Retrospective data analyses of 42 cochleae.

SETTING

Tertiary care medical center.

METHODS

Diameter (A value) and width (B value) of the cochlea were measured in HOROS software. The CDL and the 2-turn length were determined by the elliptic circular approximation (ECA). In addition, the CDL, the 2-turn length, and the angular length were determined via HOROS software by the multiplanar reconstruction (MPR) method.

RESULTS

CDL values were significantly shorter in MRI by MPR ( = 1.38 mm, < .001) but not by ECA. Similar 2-turn length measurements were significantly lower in MRI by MPR ( = 1.67 mm) and ECA ( = 1.19 mm, both < .001). In contrast, angular length was significantly higher in MRI ( = 26.79°, < .001). When the values were set in relation to the frequencies of the cochlea, no clinically relevant differences were estimated (58 Hz at 28-mm CDL).

CONCLUSION

In the presented study, CDL was investigated in CT and MRI by using different approaches. Since no clinically relevant differences were found, diagnostics with radiation may be omitted prior to cochlear implantation; thus, a concept of radiation-free cochlear implantation could be established.

PubMed: 34595367
DOI: 10.1177/2473974X211045312