Radiological measurement of cochlear dimensions in cochlear hypoplasia and its effect on cochlear implant selection

Patients with Mondini deformty: is standard electrode necessary?

PURPOSE

The aim of this study is to compare the results of auditory perception tests and speech sound evaluations with electrode array length in patients with Mondini deformity.

METHODS

The study included 14 patients who underwent cochlear implantation and radiologically confirmed Mondini deformity between 2007 and 2021 in our clinic. While 7 patients received standard electrode arrays from the MED-EL brand, the remaining 7 received shortened electrode arrays from the MED-EL brand. Differences in auditory perception, articulation, and speech intelligibility between the two groups were examined. Auditory perception tests were administered to these patients preoperatively and at least 2 years after cochlear implant surgery. The patients' auditory perception performance was evaluated using single, double, and triple closed-set word tests (MTP-3, MTP-6, MTP-12), two-syllable open-set word test, Glendonald Auditory Screening Procedure (GASP) tests for articulation, Phonemic Synthesis Test (SST) for phonemic knowledge, and Speech Intelligibility Rating (SIR) test for speech intelligibility.

RESULTS

Both groups did not show statistically significant differences in auditory perception tests (MTP-3, MTP-6, MTP-12, two-syllable open-set word test), speech sound tests (SST), and speech intelligibility test (SIR). Significant improvement was observed in all tests in both groups when compared preoperatively and postoperatively.

CONCLUSION

No significant difference was observed in auditory perception and speech sound tests between groups with short and standard electrode arrays in patients with Mondini deformity. The option of using short electrode arrays during implantation in patients with Mondini deformity can be preferred without doubt in terms of outcomes.

Evaluation of automatic cochlear dimension measurement using ALPACA: a comparative study

BACKGROUND

Cochlear dimension measurements are critical in diagnosing and managing congenital sensorineural hearing loss.

OBJECTIVES

To evaluate the feasibility and reliability of an automated landmark approach for measuring cochlear dimensions (A-, B- and H-values).

MATERIAL AND METHODS

Cochlear parameters from 100 patients were measured by MPR, manual three-dimensional and ALPACA. We assessed intra- and inter-observer reliability as well as inter-method reliability. Statistical analyses were conducted to detect differences between the right and left ears, as well as to assess the relevance of the values obtained using ALPACA.

RESULTS

All A-, B-, and H-values measured by the various methods showed a high intra-observer reliability with intra-class correlation coefficients (ICC) ranging from 0.70 to 0.99, and values gained by ALPACA reaching the highest ICC. Inter-method reliability was at a good level with ICC ranging from 0.51 to 0.86. There were no significant differences between the right and left ears' measured values. Obvious positive correlations existed among cochlear dimensions measured by ALPACA.

CONCLUSIONS AND SIGNIFICANCE

The ALPACA method can be used to measure cochlear dimensions. Values obtained by the method demonstrate high reliability and consistency with a significant reduction in intra-observer variability compared to results from conventional MPR and manual 3D measurements.

The Cochlear Size Variations in Incomplete Partitions with Multiplanar Images on Pediatric Temporal Bone CT

Objectives

The purpose of the study was to evaluate cochlea dimensions by the multiplanar reconstruction of high-resolution computed tomography that could be useful in diagnosing incomplete partition (IP) malformations.

Methods

This study included 32 patients with 64 side cochleae diagnosed with IP defect and 38 cochleae as the control without any defect. Basal turn length (BL), cochlear height (CH), Mid-apical length (MAL), Mid-apical height, Cochlear length (A), and Cochlear width (B) were measured on reformat images.

Results

Twenty cochleae of these patients have been diagnosed with IP type I, 34 with IP type II, and 10 with IP type III. The MAL values are shorter than the control group in IP types I and III (p<0.001, p<0.001). BL values are shorter in IP type III cases (p<0.001). In IP II cases, BL and MAL values overlapped with the control group. CH did not differ significantly from the control group in any IP type. A and B values were significantly lower than the control group for IP I and III (p<0.01). There is a positive correlation between A and B values for all IP types (p<0.01).

Conclusion

Quantitative data about differences in the size and shape of the cochlea in IP cases would help differentiate them from the normal cochlea. Since A and B values showed a positive correlation, it is suggested that A and B values can be used to estimate CDL for IP types.

Variation in cochlear size: A systematic review

BACKGROUND

Advancements in imaging and implantation technology have invited reexamination of the classic teaching that the human cochlea maintains uniform size across demographics. Yet, studies yield conflicting results and relatively few broad systematic reviews have examined cochlear size variation.

PURPOSE

The purpose of this study is to quantify cochlear variability across eight different measurement categories and suggest normative values and ranges for each with consideration of disease state and gender where possible.

METHODS

A systematic search was conducted up to October 1, 2022, using the search terms "Cochlea/anatomy and histology"[Mesh]) AND 'size'" with filters "Humans" and "English" across three databases (PubMed, CINAHL, Medline). Further inclusion criteria involved reporting of numerical measurements in any of the eight included categories.

RESULTS

Of the 625 articles manually reviewed for relevance by title and abstract, 91 were selected for full-text review and 33 met all eligibility criteria. 5,791 cochleae were included and weighted means and ranges were calculated: "A" value (defined as the distance from the round window, through the modiolus, to the oppsite lateral wall) = 9.23 mm (8.43-10.4 mm, n = 2559); cochlear duct length (CDL) = 33.04 mm (range 28.2-36.4 mm, n = 2252); cochlear height = 5.14 mm (2.8-6.9 mm, n = 2098); the basal turn lumen diameter = 2.09 mm (1.7-2.2 mm, n = 617); "B" value (defined as perpendicular to "A" value and in the same plane) = 6.52 mm (5.73-6.9 mm, n = 908); width of the basal turn = 6.4 mm (6.22-6.86 mm, n = 356); height of the basal turn = 1.96 mm (1.77-2.56 mm, n = 204); length of the basal turn 21.87 mm (21.03-22.5 mm, n = 384).

CONCLUSION

A notable size range exists across the eight different cochlear parameters considered and we provide normative values for each measurement. Females tend to have smaller CDL and "A" value than males and the sensorineural hearing loss patients had smaller CDL and "A" value but larger cochlear height than the general population.

A novel method of identifying inner ear malformation types by pattern recognition in the mid modiolar section

Identification of the inner ear malformation types from radiographs is a complex process. We hypothesize that each inner ear anatomical type has a uniqueness in its appearance in radiographs. The outer contour of the inner ear was captured from the mid-modiolar section, perpendicular to the oblique-coronal plane, from which the A-value was determined from CT scans with different inner ear anatomical types. The mean A-value of normal anatomy (NA) and enlarged vestibular aqueduct syndrome (EVAS) anatomical types was greater than for Incomplete Partition (IP) type I, II, III and cochlear hypoplasia. The outer contour of the cochlear portion within the mid-modiolar section of NA and EVAS resembles the side view of Aladdin’s lamp; IP type I resembles the side-view of the Sphinx pyramid and type II a Pomeranian dog’s face. The steep spiraling cochlear turns of IP type III resemble an Auger screw tip. Drawing a line parallel to the posterior margin of internal auditory canal (IAC) in axial-view, bisecting the cavity into cochlear and vestibular portions, identifies common-cavity; whereas a cavity that falls under the straight-line leaving no cochlear portion identifies cochlear aplasia. An atlas of the outer contour of seventy-eight inner ears was created for the identification of the inner malformation types precisely.