A novel cochlear measurement that predicts inner-ear malformation

Khurayzi, Tawfiq; Almuhawas, Fida; Alsanosi, Abdulrahman; Abdelsamad, Yassin; Doyle, Úna; Dhanasingh, Anandhan

doi:10.1038/s41598-021-86741-x

Cited by 15 publications

(21 citation statements)

References 34 publications

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“…In mild or ambiguous cases of IEM, radiographic measurements may be a crucial diagnostic feature that distinguishes, not only a normal inner ear from an ear exhibiting an IEM, but may also help in differentiating distinct types of IEM from each other. However, currently existing parameters for measuring temporal bone structures are determined in a certain plane of sectional imaging that is chosen individually by each examiner, which significantly contributes to interobserver variability (16,20,21).…”

Section: Introductionmentioning

confidence: 99%

Cochlear and Vestibular Volumes in Inner Ear Malformations

et al. 2022

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Objective: A "gold standard" for quantitatively diagnosing inner ear malformations (IEMs) and a consensus on normative measurements are lacking. Reference ranges and cutoff values of inner ear dimensions may add in distinguishing IEM types. This study evaluates the volumes of the cochlea and vestibular system in different types of IEM. Study Design: Retrospective cohort. Setting: Tertiary academic center. Patients: High-resolution CT scans of 115 temporal bones (70 with IEM; cochlear hypoplasia [CH]; n = 19), incomplete partition (IP) Types I and III (n = 16), IP Type II with an enlarged vestibular aqueduct (Mondini malformation; n = 16), enlarged vestibular aqueduct syndrome (n = 19), and 45 controls. Interventions: Volumetry by software-based, semiautomatic segmentation, and 3D reconstruction. Main Outcome Measures: Differences in volumes among IEM and between IEM types and controls; interrater reliability.Results: Compared with controls (mean volume, 78.0 mm 3 ), only CH showed a significantly different cochlear volume (mean volume, 30.2 mm 3 ; p < 0.0001) among all types of IEM. A cutoff value of 60 mm 3 separated 100% of CH cases from controls. Compared with controls, significantly larger vestibular system volumes were found in Mondini malformation (mean difference, 22.9 mm 3 ; p = 0.009) and IP (mean difference, 24.1 mm 3 ; p = 0.005). In contrast, CH showed a significantly smaller vestibular system volume (mean difference, 41.1 mm 3 ; p < 0.0001). A good interrater reliability was found for all three-dimensional measurements (ICC = 0.86-0.91). Conclusion: Quantitative reference values for IEM obtained in this study were in line with existing qualitative diagnostic characteristics. A cutoff value less than 60 mm 3 may indicate an abnormally small cochlea. Normal reference values for volumes of the cochlea and vestibular system may aid in diagnosing IEM.

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Section: Introductionmentioning

confidence: 99%

Cochlear and Vestibular Volumes in Inner Ear Malformations

et al. 2022

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“…The number of CT scans with various anatomical types identified in this study from the university database is more than the previous study. 9 One sample was more in NA type, 14 samples were more in…”

Section: Demographicsmentioning

confidence: 96%

“…8 In our previous study, we reported an average diameter of the cochlear basal turn (A-value) <8 mm for IP-III and CH, whereas it is >8 mm among those with normal anatomy (NA), EVAS, IP-II, and IP-I. 9 It was concluded that the A-value alone cannot be a predictor of the IEM types.…”

Section: Introductionmentioning

confidence: 96%

“…Identification of different IEM types may help the operating surgeon to limit surgical and CI electrode insertion complications 8 . In our previous study, we reported an average diameter of the cochlear basal turn (A‐value) <8 mm for IP‐III and CH, whereas it is >8 mm among those with normal anatomy (NA), EVAS, IP‐II, and IP‐I 9 . It was concluded that the A‐value alone cannot be a predictor of the IEM types.…”

Section: Introductionmentioning

confidence: 99%

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A novel three‐step process for the identification of inner ear malformation types

Dhanasingh

Weiss

Erhard

et al. 2022

Laryngoscope Investig Oto

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Objective: We hypothesize that visualizing inner-ear systematically in both cochlear view (oblique coronal plane) and in mid-modiolar section (axial plane) and following three sequential steps simplifies, identification of inner-ear malformation types.Methods: Pre-operative computer-tomography (CT) scans of temporal bones of 112 ears with various inner ear malformation (IEM) types were taken for analysis.Images were analyzed using DICOM viewers, 3D slicer, and OTOPLAN ® . The innerear was captured in the oblique-coronal plane for the measurement of length and width of cochlear basal turn which is also called as A-, and B-values respectively (Step 1). In the same plane, the angular-turns of lateral-wall (LW) of cochlear basal turn were measured (Step 2). As Step 3, the mid-modiolar section of inner ear was captured in the axial plane by following the A-value and perpendicular to cochlear view. From the mid-modiolar section, the outer-contour of inner ear was captured manually by following contrasting gray area between fluid filled and bony promontory and was compared to known resembling objects to identify IEM types (Step 3). Results: Following reference values have emerged from our analysis: A-, and B-values (Step 1) on average are >8 mm and >5.5 mm respectively, in normal cochleae (NA), enlarged vestibular aqueduct syndrome (EVAS), incomplete partition (IP) type-I and -II, whereas it is <8 mm and <5.5 mm respectively, in IP type-III and cochlear hypoplasia (CH). Angular-turn of LW is consistently observed in cochlear basal turn (Step 2), is 540 in NA and EVAS, 450 in IP-II, and 360 in IP types I & III. In subjects with CH type, angular-turn of LW is either 360 or 450 or 540 . In true mid-modiolar section, outer-contour of inner-ear (Step-3), other than in CH and cystic inner-ear malformations, resembles recognizable shapes of known objects. Absence of EVA is an additional characteristic that confirms diagnosis of CH when the A-, B-values, and angular-turn of LW can be similar to other anatomical types. Drawing a straight line Anandhan E. Dhanasingh and Nora M. Weiss contributed equally to this study.

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“…To mitigate this, 3D segmentation has established itself in clinical practice as a routine imaging technique for the visualization of anatomical inner ear structures after the CT imaging has shown abnormities [ 3 ]. The measurement of the cochlear diameter (A-value) from the pre-operative imaging is useful in the assessment of the cochlear size in those with a normal inner ear anatomy; however, it is not applicable in cases with inner ear malformation [ 4 ]. The electrode array length selection based on the A-value measurement, which is a part of the pre-operative image assessment, is only valid for cochleae with 2 ½ turns and not for cochleae with a cystic apex.…”

Section: Introductionmentioning

confidence: 99%

Analysis of Cochlear Parameters in Paediatric Inner Ears with Enlarged Vestibular Aqueduct and Patent Cochlea

Kang

et al. 2022

JPM

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Is cochlear implant (CI) electrode selection for cochleae with an enlarged vestibular aqueduct (EVA) the same as that for patent cochleae with a normal inner ear structure? Preoperative high-resolution computed tomography (HRCT) images of 247 ears were assessed retrospectively. The A-value, B-value, and H-value were measured with OTOPLAN, and Bell curves were created to show the distribution. All ears with EVA were re-evaluated using a 3D slicer to confirm whether incomplete partition type II (IP II) existed. The Mann–Whitney U-test was applied to determine a statistically significant difference. After adjustment with the Bonferroni correction method, a p-value ≤ 0.006 was considered significant. In total, 157 ears with patent cochlea and 90 ears with EVA were assessed. Seventy (82%) of the EVA ears had an IP II malformation, and 14 (19%) of these were not detected by CT scan but were later seen through the 3D reconstruction. A significant difference was found for the A value and B value between the patent cochleae and EVA-only and between the patent cochleae and EVA with IP II. Most EVA cases had an IP II malformation. The basal turn of the cochlea may be smaller in EVA cases than in the patent cochleae. Electrode selection should be adjusted accordingly.

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A novel cochlear measurement that predicts inner-ear malformation

Cited by 15 publications

References 34 publications

Cochlear and Vestibular Volumes in Inner Ear Malformations

Cochlear and Vestibular Volumes in Inner Ear Malformations

A novel three‐step process for the identification of inner ear malformation types

Analysis of Cochlear Parameters in Paediatric Inner Ears with Enlarged Vestibular Aqueduct and Patent Cochlea

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