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Imaging is a useful adjunct to the clinical and audiometric information and is often critical to confirm the correct diagnosis and prevent potential complications.
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High-resolution computed tomography (HRCT) without contrast is the modality of choice for the demonstration of fenestral and retro-fenestral (cochlear) spongiotic lesions.
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Both HRCT and MRI are recommended before cochlear implantation surgery in patients with a far-advanced otosclerosis.
Impact of Imaging in Management of Otosclerosis
Section snippets
Key points
Disease overview
The pathophysiologic hallmark of the fenestral subtype of otosclerosis is remodeling of the temporal bone that is primarily taking place in the area of the oval window, specifically in its anterior part, the fissula ante fenestram, which is a groove between the oval window and the cochleariform process. During the active (otospongiotic) stage of the disease, hypodense foci of bone can be identified in this area.8 These foci will be replaced later by sclerotic bone in the nonactive
Fenestral and retro-fenestral otosclerosis: imaging diagnosis
The most common manifestation of fenestral otosclerosis, especially in its spongiotic active stage, is demineralization of the fissula ante fenestram, anterior to the oval window (Fig. 1). In the nonactive otosclerosis, this area becomes sclerotic and in advanced stages of the disease this sclerosis can thicken and obliterate the oval window. The former stage of the disease is usually easier to detect, whereas the later becomes detectable only when significant otosclerotic bone causes
Imaging-based grading systems for otosclerosis
Many types of grading systems were developed for otosclerosis based on surgical and histologic findings. Nonetheless, none of these systems are widely accepted. Several radiographic grading systems based on computed tomography were developed in order to describe the location and stage of otosclerosis and often the relationship of the disease radiographic stage and audiometric performance.9, 11, 12, 13, 14 Rotteveel and colleagues14 demonstrated a grading system based on the histologic
Imaging before referral for stapes surgery
The diagnosis of ORHL and the decision to refer patients for stapes surgery (ie, middle ear exploration with possible stapedectomy/stapedotomy or ossiculoplsty) as part of hearing rehabilitation alternatives have been traditionally defined when patients have a history of conductive or mixed hearing loss (with a significant conductive component) with absent stapedial reflexes (provided pure tone thresholds are still good enough to elicit stapedial reflex), a normal tympanic membrane on otoscopy,
Alternative diagnosis to otosclerosis demonstrated with imaging
Certain clinical situations might lead the clinician to suspect that a nonotosclerosis diagnoses is mimicking an ORHL and should call for imaging as additional foundation for verification of the underlying diagnoses.8, 10 Common examples are summarized in Box 1 and include mixed hearing loss, significant bilateral conductive or mixed hearing loss (in these cases the value of audiometric test might be limited because of the possible masking dilemma); sensorineural hearing loss; children with
The use of preoperative imaging in otosclerosis to avoid intraoperative complications
Preoperative imaging might also be used to avoid intraoperative complications during procedures for otosclerosis, which is the case with some inner-ear malformations that might jeopardize an outcome like enlarged vestibular aqueduct or X-linked mixed deafness, with accompanying defects in the fundus of the internal auditory canal (Fig. 5). These radiographic findings carry with them a significant risk of intraoperative perilymph gusher during stapes surgery and subsequent sensorineural hearing
Preoperative imaging assessment checklist
Meticulous and systematic assessment of available preoperative imaging can cover the domains that should be inspected during the diagnostic and surgical planning stage and help avoid the aforementioned misdiagnoses and possible intraoperative complications (Table 3).
Preoperative imaging in retro-fenestral (cochlear) otosclerosis
When retro-fenestral (cochlear) otosclerosis progresses and cochlear implantation is being considered, imaging (both HRCT and MRI) is of paramount importance. Both imaging modalities might be used to evaluate the patency of the cochlea in cases of far-advanced otosclerosis whereby the cochlear lumen may be obstructed (especially when implantation is delayed) and require drill-through or drill-out techniques. It has been demonstrated that these patients have higher numbers of partial electrode
MRI for evaluation of otosclerosis
Although HRCT is the modality of choice for most aspects of otosclerosis, additional imaging modalities might be useful for preoperative diagnosis and delineation of anatomy in otosclerosis. MRI will often be the first modality to assess patients with sensorineural or mixed hearing loss; hence, knowing to identify otosclerosis in this modality is important.30 Although MRI is less useful for the demonstration of bony pathology and anatomy, it is very useful for the evaluation of the patency of
Single-photon emission computed tomography for evaluation of otosclerosis
Single-photon emission computed tomography (SPECT) using 99 technetium-diphosphonates (because diphosphonates are highly adsorbed by the immature hydroxyapatite of active otospongiotic foci).10 Scintigraphic examination using similar agents were tried but suffered from poor spatial orientation.10 Berrettini and colleagues10 suggested this option for diagnostic purposes in difficult cases and for medical treatment follow-up. In this study, SPECT exhibited high sensitivity and specificity (95.2%
Postoperative imaging in otosclerosis: complications and results assessment
Stapes surgery is a relatively safe procedure with a high rate of air-bone gap closure, and greater than 90% of patients report better hearing 1 year after the surgery.34 Profound sensorineural hearing loss occurs in less than 1% of the cases, and worsening of the BC thresholds greater than 5 dB occur in about 5% of the cases.34, 35, 36 Incomplete closure of air-bone gap and a remaining conductive or mixed hearing loss occur in 6.5% to 27.0% of the cases.34, 37 Both sensorineural hearing loss
Summary
The use of imaging in otosclerosis for diagnosis, preoperative assessment, and follow-up gives the clinician an additional tier of validation and evaluation of patients’ diagnoses. This evaluation might help in offering the correct solution for hearing-impaired individuals whose type of hearing loss is likely to be ORHL. The use of imaging in otosclerosis is expected to reduce complication rates, failures, and disappointment. Imaging might be also used following an unsuccessful stapes procedure
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Cited by (14)
Brazilian Society of Otology task force – Otosclerosis: evaluation and treatment
2023, Brazilian Journal of OtorhinolaryngologyMeasuring the density of the fissula antefenestram and the section of the basal turn of the cochlea: Are they useful in the radiological diagnosis of otosclerosis?
2022, Journal of OtologyCitation Excerpt :Thus, the HRCT might be needed in particular cases for differential diagnosis.( Wolfovitz and Luntz, 2018). However, the routine use of CT imaging with diagnostic purposes is a matter of discussion, despite the increasing accuracy reported with the most recent techniques(McElveen Jr and Kutz Jr, 2018).
Availability of audiological evaluation for the differential diagnosis of clinical otosclerosis
2020, Auris Nasus LarynxCitation Excerpt :In other words, the ear with a positive CAR is likely to be the one with incudostapedial disconnection. The usefulness of computed tomography (CT) findings for otosclerosis was described more than 50 years ago, although controversy still remains regarding the correlation between imaging and the degree of hearing loss in otosclerosis [17]. In previous reports, the sensitivity and specificity of CT imaging for surgically confirmed otosclerosis ranged from 61 to 95% and 75–100%, respectively [18].
High-resolution computed tomography and pure-tone audiometry in patients with otosclerosis in the spongiotic phase
2023, Journal of Laryngology and OtologyRadiological parameters and audiometric findings in otosclerosis: Is there any relationship?
2023, Journal of Laryngology and OtologyMSCT post-processing technologies for diagnosing otosclerosis
2024, Chinese Journal of Interventional Imaging and Therapy
Disclosure: The authors have nothing to disclose.