The Normal Adult Human Internal Auditory Canal: A Volumetric Multidetector Computed Tomography Study

Essbaiheen, Fahad; Hegazi, Tarek M.; Rosenbloom, Lorne

doi:10.1097/mao.0000000000001388

Cited by 4 publications

(6 citation statements)

References 10 publications

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“…This is in accordance to previous studies, which reported a mean IAC diameter between 5 and 6 mm and an IAC diameter range between 2 and 8 mm to be normal [ 15 , 17 , 29 , 30 ]. In contrast, only few previous studies reported volumetric data on a normal IAC [ 31 ]. Furthermore, information on volumes of hypoplastic IAC as well as IAC size in IEM is unknown.…”

Section: Discussionmentioning

confidence: 99%

Internal auditory canal volume in normal and malformed inner ears

Bächinger

Breitsprecher

Pscheidl

et al. 2022

Eur Arch Otorhinolaryngol

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Purpose A narrow bony internal auditory canal (IAC) may be associated with a hypoplastic cochlear nerve and poorer hearing performances after cochlear implantation. However, definitions for a narrow IAC vary widely and commonly, qualitative grading or two-dimensional measures are used to characterize a narrow IAC. We aimed to refine the definition of a narrow IAC by determining IAC volume in both control patients and patients with inner ear malformations (IEMs). Methods In this multicentric study, we included high-resolution CT (HRCT) scans of 128 temporal bones (85 with IEMs: cochlear aplasia, n = 11; common cavity, n = 2; cochlear hypoplasia type, n = 19; incomplete partition type I/III, n = 8/8; Mondini malformation, n = 16; enlarged vestibular aqueduct syndrome, n = 19; 45 controls). The IAC diameter was measured in the axial plane and the IAC volume was measured by semi-automatic segmentation and three-dimensional reconstruction. Results In controls, the mean IAC diameter was 5.5 mm (SD 1.1 mm) and the mean IAC volume was 175.3 mm3 (SD 52.6 mm3). Statistically significant differences in IAC volumes were found in cochlear aplasia (68.3 mm3, p < 0.0001), IPI (107.4 mm3, p = 0.04), and IPIII (277.5 mm3, p = 0.0004 mm3). Inter-rater reliability was higher in IAC volume than in IAC diameter (intraclass correlation coefficient 0.92 vs. 0.77). Conclusions Volumetric measurement of IAC in cases of IEMs reduces measurement variability and may add to classifying IEMs. Since a hypoplastic IAC can be associated with a hypoplastic cochlear nerve and sensorineural hearing loss, radiologic assessment of the IAC is crucial in patients with severe sensorineural hearing loss undergoing cochlear implantation.

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Section: Discussionmentioning

confidence: 99%

Internal auditory canal volume in normal and malformed inner ears

Bächinger

Breitsprecher

Pscheidl

et al. 2022

Eur Arch Otorhinolaryngol

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“…In the radiological assessment of such processes, it would seem more desirable to have a reproducible quantifiable objective measure of the IAC rather than relying on the subjective impression of IAC asymmetry or unidimensional measurements of the acoustic pore. Such a quantitative measure could also serve as a baseline for subsequent comparisons when monitoring a disease process (15). For this reason, we evaluated morphometry, angles, and volume of IAC in our study.…”

Section: Discussionmentioning

confidence: 99%

“…Due to the developments in radiological imaging techniques in recent years, imaging methods such as magnetic resonance imaging (MRI) and computed tomography (CT) are used extensively to elucidate the anatomy of IAC (7, 13 -16). It was determined that the studies using CT or MRI in the literature are related to the distance of IAC to various parts of the temporal bone, length of canal, diameters of IAP and shapes of IAC (4,6,7,15,17). When the literature studies were examined, we believe that there is a great need a study with more comprehensive, more organized and including more parameters related to IAC.…”

Section: Introductionmentioning

confidence: 99%

Determination of Morphometry and Volume of the Internal Auditory Canal

Bilir

Fazlıoğulları

TATAR>

et al. 2023

Kocatepe Tıp Dergisi

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OBJECTIVE: The internal auditory canal (IAC) also known as internal acoustic meatus is a bone channel that connects the internal ear to the posterior cranial fossa. The mean length is approximately 1 cm. The edge of the IAC is called internal acoustic pore (IAP), and the edge of this aperture is blunt and rounded. Important formations such as facial nerve, vestibulocochlear nerve, labyrinth artery and labyrinth vein pass through the IAC. In addition, on the precise determination of the morphometry in surgical interventions on the temporal lobe, MAI is vital. Therefore, in this study, it was aimed to determine the morphometry and volume of MAI.MATERIAL AND METHODS: The study was carried out on the CT images of 210 individuals randomly from the normal population between the ages of 10-90. Morphometric measurements of IAC (lateral angle (LA), canal length, anteroposterior (AP), diameter of IAP, distance from IAP to vestibular aqueduct (VA)) were performed. In addition, the shape and volume of IAC was determined in this study. Cases were divided into 7 different subgroups, 10-14, 15-20, 21-30, 31-40, 41-50, 51-60 and 61 years old, depending on their age.RESULTS: In this study, CT images of 210 patients were analyzed. The mean length of the MAI was 9.5±1.6mm, the AP diameter was 6.3±1.5mm, the distance from the entrance part to the VA was 15.1±6.64mm, the volume was 290±120mm3, and the LA was 50±14º.CONCLUSIONS: When the outcome data were compared by gender, it was found statistically significant that the right AP diameter was higher in men, the length of the right MAI and both sides LA were higher in women. In addition, when the volumes of MAI were compared by age groups, it was determined that the 10-14 age group was smaller than the other age groups.

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“…2) A recent study of computed tomography (CT) scans of the IAC found that the median IAC volume of adults was 191 mm 3 and 202 mm 3 in the right and left ears respectively, including both sexes. 8 Additionally, a study of sporadic non-NF2 intracanalicular tumors found that AHDR was higher in tumors that had a growing IAC component. 14…”

Section: Discussionmentioning

confidence: 99%

“…We hypothesized that internal auditory canal (IAC) tumor volume > 200 mm 3 would be associated with the development of hearing loss based on a study which indicated median internal auditory canal (IAC) volume of adults ranged between 191 and 202 mm 3 on computerized tomography (CT) scan. 8 Understanding the relationship of these audiometric and imaging characteristics with hearing loss may be useful in predicting which patients are at risk of developing significant hearing loss over time and therefore help guide the decision to offer future intervention.…”

Section: Introductionmentioning

confidence: 99%