Imaging Studies in Otosclerosis: An Up-to-date Comprehensive Review

Abstract

Introduction Otosclerosis is a primary osteodystrophy of the otic capsule, frequently responsible for acquired hearing loss in adults. Although the diagnostic value of imaging investigations in otosclerosis is debatable, they might still be employed with different goals within the context of the disease. Objectives The present paper aims to review the most recent literature on the use of imaging studies in otosclerosis for the most varied purposes, from routine application and differential diagnosis to prognostic prediction and investigation of surgical failure. Data Synthesis The diagnosis of otosclerosis is usually clinical, but computed tomography (CT) is paramount in particular cases for the differential diagnosis. The routine use, however, is not supported by strong evidence. Even so, there is growing evidence of the role of this method in surgical planning and prediction of postoperative prognosis. In specific scenarios, for example when superior semicircular canal dehiscence (SSCD) syndrome is suspected or in surgical failure, CT is crucial indeed. Magnetic resonance imaging (MRI), however, has limited - although important - indications in the management of individuals with otosclerosis, especially in the evaluation of postoperative complications and in the follow-up of medical treatment in active ostosclerosis. Conclusion Imaging studies have a broad range of well-established indications in otosclerosis. Besides, although the routine use of CT remains controversial, the most recent papers have shed light into new potential benefits of imaging prior to surgery.

Keywords: X-Ray; computed; diagnostic imaging; magnetic resonance imaging; otosclerosis; stapes surgery; tomography.

Fig. 1

Computed tomography scan of temporal bone. Axial view at the level of the oval window, showing a hypodensity focus limited to the fissula ante fenestram (black arrow), typical of otosclerosis. Source: the authors.

Fig. 2

Computed tomography scan of temporal bone. Axial view at the level of the cochlear basal turn, with a pericochlear hypodensity surrounding the cochlear turns, determining the “double ring sign”, typical of retrofenestral otosclerosis. Source: the authors.

Fig. 3

Computed tomography scan of temporal bone. Axial view at the level of the oval window, showing the presence of contour irregularities on the surface of the otic capsule (black circle), typical of inactive otosclerosis. Source: the authors.

Fig. 4

Computed tomography scan of temporal bone. Axial view at the level of the facial recess, demonstrating the presence of a hypodense focus causing an increase in volume at the region of the round window (black circle), with apparent continuity with a pericochlear focus (black arrow). Source: the authors.

Fig. 5

Computed tomography scan of temporal bone. Axial view at the level of the oval window, showing the presence of an obliterative otosclerotic focus (black arrow). Source: the authors.

Fig. 6

Computed tomography scan of temporal bone. Oblique view at the level of the superior semicircular canal, showing an area of dehiscence (black arrow). Source: the authors.

Fig. 7

Computed tomography scan of temporal bone. Axial view at the level of the oval window, showing the presence of a diverticulum in the internal auditory canal, also called “nipple sign” (black arrow). Source: the authors.

Fig. 8

Magnetic resonance imaging of the brain, 4 hours after double injection of gadolinium, at the level of the membranous labyrinth, REAL IR sequence, axial view. Areas with signal voids on the left ear might be observed, corresponding to the cochlea and vestibule, compatible with endolymphatic hydrops (black arrows). The contralateral inner ear has a comparative normal appearance (white arrows). Source: the authors.

Fig. 9

Computed tomography scan of temporal bone. Coronal view at the level of the cochlea showing a hyperdense focus on the cochlear endosteum, possibly related to ossifying labyrinthitis (black arrow). Source: the authors.