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. 2022 Oct 1;43(9):e957-e962.
doi: 10.1097/MAO.0000000000003665. Epub 2022 Sep 9.

Otopathologic and Computed Tomography Correlation of Internal Auditory Canal Diverticula in Otosclerosis

Dawson Wells, Renata M Knoll, Elliott Kozin, Jenny X Chen, Katherine L Reinshagen  1 , Hinrich Staecker  2 , Hugh D Curtin  1 , Michael J McKenna  3 , Joseph B Nadol Jr, Alicia M Quesnel
Affiliations

Otopathologic and Computed Tomography Correlation of Internal Auditory Canal Diverticula in Otosclerosis

Dawson Wells et al. Otol Neurotol. .

Abstract

Introduction: Internal auditory canal (IAC) diverticula, also known as IAC cavitary lesions or anterior cupping of the IAC, observed in otopathologic specimens and high-resolution computed tomography (CT) scans of the temporal bone are thought to be related to otosclerosis. Herein, we examined the usefulness of CT scans in identifying diverticula and determined whether IAC diverticula are associated with otosclerosis on otopathology.

Methods: One hundred five consecutive specimens were identified from the National Temporal Bone Hearing and Balance Pathology Resource Registry. Inclusion criteria included the availability of histologic slides and postmortem specimen CT scans. Exclusion criteria included cases with severe postmortem changes or lesions causing bony destruction of the IAC.

Results: Ninety-seven specimens met criteria for study. Of these, 42% of the specimens were from male patients, and the average age of death was 77 years (SD = 18 yr). IAC diverticula were found in 48 specimens, of which 46% were identified in the CT scans. The mean area of the IAC diverticula was 0.34 mm 2 . The sensitivity and specificity of detecting IAC diverticula based on CT were 77% and 63%, respectively. Overall, 27% of specimens had otosclerosis. Histologic IAC diverticula were more common in specimens with otosclerosis than those without (37.5% versus 16%; p = 0.019). Cases with otosclerosis had a greater mean histologic diverticula area compared with nonotosclerosis cases (0.69 mm 2 versus 0.14 mm 2 ; p = 0.001).

Conclusion: IAC diverticula are commonly found in otopathologic specimens with varied etiologies, but larger diverticula are more likely to be associated with otosclerosis. The sensitivity and specificity of CT scans to detect IAC diverticula are limited.

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Conflict of interest statement

J.C. has a patent pending at Grace Medical. E.K. is a scientific advisor at Desktop Metal and has a patent pending at Grace Medical. H.S. is in the surgical advisory board of MedEl and a shareholder at Rescue Hearing. M.J.McK. is the co-founder and CMO of Akouos Inc. A.Q. has a sponsored research agreement with Frequency Therapeutics, sponsored research agreement, patent pending at Grace Medical, and consulting for Alcon. The remaining authors disclose no conflicts of interest.

Figures

Figure 1.
Figure 1.. Representative CT and temporal bone histologic sections illustrating patients with an IAC diverticulum (yellow arrow).
(A, B) A left temporal bone from a 58-year-old male without otosclerosis. (C, D) A left temporal bone from a 91-year-old female with otosclerosis(*).
Figure 2.
Figure 2.. IAC diverticula in temporal bones without otosclerosis.
(A) A left temporal bone from a 88-year-old male with a large IAC diverticulum. (B) A smaller, more rounded diverticulum is seen in the right temporal bone from a 90-year-old female.
Figure 3.
Figure 3.. IAC diverticula in temporal bones with otosclerosis.
(A) A right temporal bone from a 91-year-old female with clinical and histological evidence of otosclerosis. There is a large diverticulum (yellow arrow) completely surrounded by a thin layer otosclerotic bone. (B) A right temporal bone from an 89-year-old male, also with clinical and histological diagnosis of otosclerosis. There is a much larger otosclerotic foci involving the cochlea, with a shallower diverticulum (yellow arrow). An additional cavitary lesion (*) is adjacent to the IAC diverticulum, and associated with the same focus of otosclerosis.
Figure 4.
Figure 4.. Scatter plot with diverticula area in otosclerosis and non-otosclerosis cases.
Cases with otosclerosis had a greater mean diverticula area compared to non-otosclerosis cases (p=0.001). The horizontal lines and error bars represent the mean and standard error of the mean, respectively.
See this image and copyright information in PMC

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