Otosclerosis: Incidence of Positive Findings on High-Resolution Computed Tomography and Their Correlation to Audiological Test Data

Artificial Intelligence for Otosclerosis Detection: A Pilot Study

The gold standard for otosclerosis diagnosis, aside from surgery, is high-resolution temporal bone computed tomography (TBCT), but it can be compromised by the small size of the lesions. Many artificial intelligence (AI) algorithms exist, but they are not yet used in daily practice for otosclerosis diagnosis. The aim was to evaluate the diagnostic performance of AI in the detection of otosclerosis. This case-control study included patients with otosclerosis surgically confirmed (2010-2020) and control patients who underwent TBCT and for whom radiological data were available. The AI algorithm interpreted the TBCT to assign a positive or negative diagnosis of otosclerosis. A double-blind reading was then performed by two trained radiologists, and the diagnostic performances were compared according to the best combination of sensitivity and specificity (Youden index). A total of 274 TBCT were included (174 TBCT cases and 100 TBCT controls). For the AI algorithm, the best combination of sensitivity and specificity was 79% and 98%, with an ideal diagnostic probability value estimated by the Youden index at 59%. For radiological analysis, sensitivity was 84% and specificity 98%. The diagnostic performance of the AI algorithm was comparable to that of a trained radiologist, although the sensitivity at the estimated ideal threshold was lower.

Otic Capsule Demineralization and Hearing Outcome of Stapes Surgery for Osteogenesis Imperfecta in Comparison With Otosclerosis

OBJECTIVE

To assess the location/number of otic capsule demineralization and hearing outcomes of stapes surgery (SS) for osteogenesis imperfecta (OI) compared with otosclerosis (OS).

PATIENTS

This study included 11 and 181 consecutive ears from 6 and 152 patients with OI and OS, respectively.

INTERVENTIONS

Demineralization loci observed as hypodense area of the otic capsule were examined using high-resolution computed tomography. All patients underwent SS.

MAIN OUTCOME MEASURES

Locations of the hypodense areas were classified into the anterior oval window, anterior internal auditory canal, and pericochlear area. The location/number of hypodense areas and preoperative/postoperative hearing parameters were correlated. Postoperative hearing outcome was evaluated 12 months after surgery.

RESULTS

Hypodense area was more frequently observed in OI (9 of 11 ears [81.8%]) than in OS (96 of 181 ears [53.0%]), with significant differences. Multiple sites were involved in 81.8% OI and 18.8% OS patients, showing significant differences. Preoperative air conduction (AC), bone conduction, and air-bone gap (ABG) were 48.9 ± 17.8, 28.0 ± 11.3, and 20.7 ± 8.4 dB, respectively, in OI and 56.2 ± 13.5, 30.5 ± 9.9, and 26.4 ± 9.7 dB, respectively, in OS, demonstrating greater AC and ABG in OS than in OI. Postoperative AC (31.3 ± 20.5 dB), ABG (10.6 ± 10.0 dB), and closure of ABG (12.1 ± 4.7 dB), that is, preoperative ABG minus postoperative ABG of OI, were comparable to those of OS (AC, 30.9 ± 13.3 dB; ABG, 7.0 ± 7.4 dB; closure of ABG, 20.1 ± 11.6 dB).

CONCLUSION

OI ears showed more severe demineralization of otic capsule than OS ears. However, favorable hearing outcomes could be obtained through SS for OI and OS ears.

Radiological parameters and audiometric findings in otosclerosis: is there any relationship?

OBJECTIVE

The role of high-resolution computed tomography scans in otosclerosis remains uncertain. There is a debate over the relationship between radiological and audiometric findings among patients.

METHOD

Pre-operative audiometry and high-resolution computed tomography findings from 40 ears with surgically confirmed otosclerosis were compared. High-resolution computed tomography scan data regarding the characteristics of the disease foci, the endosteal extension and the occurrence of internal auditory canal diverticula were obtained. The influence of each radiological variable on the simple pure tone average, the high-frequency pure tone average and the bone-conduction pure tone average were investigated.

RESULTS

Cases with endosteal extension (p = 0.047) and a higher number of affected sites within the otic capsule had a worse bone-conduction pure tone average, although it was only significant for the latter (p = 0.006). Those without concomitant retrofenestral disease (p = 0.019) had better simple pure tone average.

CONCLUSION

The number of sites of involvement and concomitant retrofenestral disease seem to significantly impact audiometric findings in otosclerosis.

[Role of computed tomography in the preoperative diagnosis of otosclerosis]

BACKGROUND

Otosclerosis is an osteodystrophy of the otic capsule and presents with progressive conductive hearing loss. Imaging studies, especially computed tomography (CT) and cone-beam CT, have gained increased relevance in the diagnosis of otosclerosis.

OBJECTIVE

This study investigated whether there is a correlation between the extent of otosclerosis in high-resolution or cone-beam CT and hearing loss in pure-tone audiometry.

MATERIALS AND METHODS

Based on an existing classification of otosclerotic foci, a classification was established. Preoperative CT scans of patients undergoing stapedotomy between 2015 and 2019 were evaluated and classified by two independent otorhinolaryngologists. The preoperative pure-tone audiograms were analysed and compared to the results of CT.

RESULTS

A total of 168 CT studies (i.e., 168 ears) in 156 patients with intraoperatively confirmed otosclerosis were included in our study. A correlation between the extent of the otosclerotic focus or the calculated scores and hearing loss in pure-tone audiometry (air conduction, bone conduction and air-bone-gap) could not be proven.

CONCLUSION

Preoperative CT is not obligatory. However, preoperative imaging using CT or cone-beam CT can be helpful to confirm the diagnosis and exclude other middle or inner ear pathologies as well as in planning of the surgical procedure in the overall context of otoscopy and audiometry. A correlation with the degree of hearing impairment could not be demonstrated and remains unclear.

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

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.

Feasibility of CBCT in Diagnosing Otosclerosis by Measuring CBCT Bone Density: A Preliminary Study

The aim of this study was to measure cone beam computed tomography (CBCT) derived bone density of 6 anatomic points around the otic capsule in preoperative assessment of patients with clinically suspected otosclerosis, and to compare these densities with control group. CBCT images of 21 patients (34 ears, the otosclerosis group) with surgically confirmed otosclerosis and 26 patients (52 normal ears, the control group) were evaluated in this prospective study. Six regions of interest (ROI) were set manually around the otic capsule with the slice thickness of 0.3 mm. The mean CBCT bone density these regions were measured and compared in the case and control groups. In the case group, the mean CBCT bone density at the fissula ante fenestram (FAF) was significantly lower than the control group. Moreover, at the 4 points of the other ROIs (3-6) CBCT bone densities were significantly lower in the case group compared to the control group (p < 0.01). In this group, among 13 bilateral otosclerosis, 22 ears had conductive hearing loss (CHL), 4 ears had mixed hearing loss (MHL) and among 8 unilateral otosclerosis, 5 ears had CHL, 3 ears had MHL. Our study showed the mean CBCT bone density of ROIs 1 and 6 were correlated with the average air-bone gap in the bilateral and unilateral otosclerosis group, respectively. Quantitative evaluation of CBCT with a slice thickness of 0.3 mm can be used as a suitable tool for diagnosis and follow-up of otosclerosis in temporal bone.

Correlation of Preoperative High-resolution Computed Tomography Temporal Bone Findings with Intra-operative Findings in Various Ear Pathologies

High resolution computed tomography (HRCT) is a tool which provide fine details of temporal bone and its associated pathologies which are of extreme use in making diagnosis, to evaluate extension of disease and most important to plan surgical approach. Aim of the present study was to correlate HRCT findings with operative findings in different ear pathologies. This observational, prospective study enrolled 70 patients of different ear pathologies required surgical intervention. They were subjected to HRCT temporal bone and its findings were correlated with surgical findings. Mean age of the study population was 20.3 ± 12.04 years with M: F = 1.12: 1. HRCT showed specificity and sensitivity of 100% and 92.31% respectively in detecting ossicular erosion. It was 100% sensitive and 98.51% specific in detecting LSCC erosion, 85.71% sensitive and 96.83% specific in detecting facial canal dehiscence, 100% sensitive and 98.11% specific in detecting scutum erosion, 75% sensitive and 96.97% specific to detect tegmen erosion, 100% sensitive and 97.01% specific in detecting sinus plate erosion, 100% sensitive and 95.38% specific in detecting high jugular bulb, sensitivity and specificity both are 100% in detecting labyrinthitis ossificans and 100% sensitive in detecting otosclerotic foci. HRCT findings showed a good association with operative findings in terms of sensitivity and specificity. Thus, HRCT is a acceptable tool to make diagnosis and to plan surgical approach.

CT scan findings impact on hearing thresholds in otosclerosis: A study of 108 patients

Background

The relationship between the location of otosclerotic zones and hearing thresholds has been evaluated in several studies and has generated different conflicting reports. This study was carried out in order to evaluate the relationship between otosclerotic zones extension on CT scan and pure tone audiometry (PTA) thresholds, before and after stapedotomy. Materials and Methods: 108 patients with a positive surgical diagnosis of otosclerosis, operated by the same surgeon, were enrolled in this retrospective study, performed in a tertiary referral hospital between 2015 and 2018.

Results

PTA thresholds were significantly poorer in cases of extensive otosclerosis (peri cochlear, peri vestibular, or internal auditory canal hypodensities, p = 0,001). However, for cases with hypodensity extending to the endosteum of cochlea (Type III), we have noted a significant improvement in postoperative PTA thresholds (Mean AC (air conduction) = 32,8 ± 8,16/62,97 ± 12,28 dB), Mean BC (bone conduction) = 18,3 ± 8,56/26,25 ± 15,93 dB). Conclusions: In our study, extensive and multifocal otosclerosis lesions had a statistically significant negative impact on postoperative AC and BC threshold; however, type III lesions tend to be associated with a very good prognosis.

Measuring 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?

Introduction

The role of objective parameters in terms of improvement of the accuracy of high-resolution computed tomography (HRCT) of the temporal bone in the diagnosis of otosclerosis remains unclear.

Objectives

To investigate the relationship between the density of the fissula antefenestram (FAF) and of the width of the transversal section of the basal turn of the cochlea (BTC), and the diagnosis of otosclerosis.

Methods

This is a retrospective study in which preoperative HRCT data from ears of patients submitted to stapedotomy due to otosclerosis (case group) were evaluated. For the control group, normal hearing ears having undergone HRCT for other purposes were included. Case and control HRCT images were objectively assessed by an experienced blinded radiologist. During this evaluation, measurements of the relative radiological density of the FAF and of the transversal section of the BTC were obtained. The results were compared between the groups. Also, a receiver operating characteristic curve was created and the area under the curve (AUC) was calculated for each variable. Significance level was set at .05.

Results

40 ears were included in each group. Case ears presented reduced values for the relative radiological density on the FAF (p-value<0.0001). Moreover, ears with otosclerosis (p-value: 0.022) presented lower transversal section of the BTC. The AUC for these variables reached 0.929 and 0.646, respectively.

Conclusions

Otosclerotic ears present reduced radiological density on the FAF and narrower BTC. The relative density of the FAF also shows a great diagnostic power in the context of this disease.

The use of explainable artificial intelligence to explore types of fenestral otosclerosis misdiagnosed when using temporal bone high-resolution computed tomography

Background

The purpose of this study was to explore the common characteristics of fenestral otosclerosis (OS) which are misdiagnosed, and develop a deep learning model for the diagnosis of fenestral OS based on temporal bone high-resolution computed tomography scans.

Methods

We conducted a study to explicitly analyze the clinical performance of otolaryngologists in diagnosing fenestral OS and developed an explainable deep learning model using 134,574 temporal bone high-resolution computed tomography (HRCT) slices collected from 1,294 patients for the automatic diagnosis of fenestral OS. We prospectively created an external test set with 31,774 CT slices from 144 patients, which contained 86 fenestral OS ears and 202 normal ears and used it to evaluate the performance of our otosclerosis-Logical Neural Network (LNN) model to assess its potential clinical utility. In addition, we compared the diagnostic acumen of seven otolaryngologists with the otosclerosis-LNN approach in the clinical test set, which was mixed with 78 fenestral OS and 62 normal ears. Finally, to evaluate the assisting value of the model, the seven participants were again invited to classify all cases in the clinical test set after referring to the diagnostic results of the model, to which they were blinded.

Results

The diagnostic performance of otologists was not satisfactory, and those CT samples which were misdiagnosed had similar characteristics. Based on this finding, we defined three subtypes of fenestral OS lesions that are suitable for clinical diagnosis guidance: “focal”, “transitional”, and “typical” fenestral OS. The most encouraging result is that the model achieved an area under the curve (AUC) of 99.5% (per-ear-sensitivity of 96.4%, per-ear-specificity of 98.9%) on the prospective unknown external test. Furthermore, we used this model to assist otologists and observed a consistent and significant improvement in diagnostic performance, especially for the newly defined focal and transitional fenestral OS, which led to the initial high misdiagnosis rate.

Conclusions

Our findings of the fine-grained classification of fenestral OS could have implications for future diagnosis and prevention programs. In addition, our deep OS localization network is an effective approach providing assistance to otologists to deal with the significant challenge of the misdiagnosis of fenestral OS.

Cerebrospinal Fluid Leak During Stapes Surgery: The Importance of Temporal Bone CT Reconstructions in Oblique Anatomically Oriented Planes

Stapes gusher is a massive flow of perilymph and cerebrospinal fluid leak that fills the middle ear immediately after surgical opening of the labyrinth, such as during stapedectomy. Stapes gusher usually occurs as the result of a congenital malformation that causes an abnormal communication between the perilymphatic space and the subarachnoid space involving the internal auditory canal or the cochlear duct. To date, the potential risk of stapes gusher cannot be assessed preoperatively, as there are not pathognomonic signs suggestive of this complication. However, high-resolution computed tomography scan (HRCT) of the temporal bone can provide information that may help recognizing patients at risk. Recently, an anatomic evaluation of the inner ear with oblique reformation at HRCT has been described. This reformation offers a new and more detailed topographic vision of temporal bone structures compared to the classic axial and coronal planes and may help identifying anatomical alterations otherwise not visible. In this article, we present a case of stapes gusher and the role of preoperative HRCT with oblique reformation in its prevention.

Wideband absorbance tympanometry: a novel method in identifying otosclerosis

PURPOSE

The purpose of the study was to know whether the wideband absorbance measurements can be a useful tool to identify ears with otosclerosis. The present study analyzed WBA measurements and highlighted its effectiveness in identifying ears with otosclerosis and differentiating from healthy normal ears.

METHODS

The study included 42 ears with otosclerosis which were compared with an equal sample size of healthy normal ears. WBA across frequencies and wideband average absorbance (375-2000 Hz) at the peak and ambient pressure, and resonance frequency were measured and analyzed.

RESULTS

Results showed that WBA levels increased with an increase in frequencies up to 2000 Hz and decreased thereafter, both in the otosclerosis and healthy normal ears. The mean WBA in the otosclerosis group was significantly lower in the 250-2000 Hz frequency range than in the healthy normal ear group. The WBA values at ambient pressure reduced significantly up to 500 Hz for the healthy normal ear group and 1500 Hz for otosclerosis group, compared with peak pressure. Further, the analysis of wideband average absorbance at ambient pressure showed reduced absorbance (0.35) and higher resonance frequency (1350.33 Hz) in the otosclerosis group compared with the healthy normal ear group (0.60 and 930.14 Hz, respectively). ROC analysis indicated that WBA is suitable for identifying otosclerotic ears and also in differentiating from healthy normal ears based on WBA values from 250 to 1500 Hz. High diagnostic values of WBA (> 90% sensitivity and specificity) were observed at a frequency of 1000 Hz.

CONCLUSIONS

The inclusion of WBA into clinical routine test procedures could be a useful tool for detecting otosclerosis. Further research is required to validate its clinical use in combination with other middle ear measures.

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

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.

Measurement of Wideband Absorbance as a Test for Otosclerosis

The purpose of this study was to investigate the effectiveness of wideband energy absorbance in diagnosing otosclerosis by comparing the differences in acoustic absorbance between otosclerotic and normal ears. Exactly 90 surgically confirmed otosclerotic ears were included in the test group. The control group consisted of 126 matched normal-hearing subjects. The Titan hearing test platform (Interacoustics) was used for absorbance and acoustic immittance tests. Energy absorbance, measured at tympanometric peak pressure, was analyzed in the range 226–8000 Hz. Differences between normal and otosclerotic ears were analyzed in quarter-octave bands. Wideband absorbance, i.e., absorbance averaged over the 226–2000 Hz band, and resonance frequency were calculated and compared between normal and otosclerotic ears. Significant differences between the absorbance of normal and otosclerotic ears were found, especially at low and middle frequencies. No significant effect of ear side or gender was observed. For average wideband absorbance and resonance frequency, less pronounced (although significant) differences were found between normal and otosclerotic ears. Measurement of peak-pressure energy absorbance, averaged over a frequency band around 650 Hz, provides a valid criterion in testing for otosclerosis. The test is highly effective, with a sensitivity and specificity of over 85% and area under receiver operating characteristic curve above 0.9. Average wideband absorbance can also be used, but its effectiveness is lower. Other immittance-related measures are considerably less effective.

Sensitivity of High-Resolution Computed Tomography in Otosclerosis Patients undergoing Primary Stapedotomy

OBJECTIVE

To determine the incidence of abnormal otospongiotic or otosclerotic findings on high-resolution computed tomography (HRCT) as read by local radiologists in patients with surgically-confirmed otosclerosis.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary-referral private otology-neurotology practice.

PATIENTS

Adults (>18 years old) with surgically-confirmed otosclerosis between 2012 and 2017 with a HRCT performed preoperatively.

INTERVENTION

Preoperative HRCT then stapedotomy.

MAIN OUTCOME MEASURES

Positive identification and location of radiographic otosclerosis as reported by the local radiologist. We then correlated the CT with surgical location as documented at time of surgery. Audiometry, demographic data, intraoperative findings, and surgical technique were secondarily reviewed.

RESULTS

Of the 708 stapes surgeries were performed during the study time frame. Preoperative HRCT scans were available for 68 primary stapedotomy surgeries performed in 54 patients. Otosclerosis was reported in 20/68 (29.4%). Following a negative report by the local radiologist, a re-review by the surgeon and/or collaborating neuroradiologist confirmed otosclerosis in 12/48 additional cases (25.0%). There was an overall sensitivity of 47.1%. Intraoperatively, cases with negative reads tended to have more limited localization at the ligament (8.7%) or anterior crus (39.1%), compared with positive reads, which demonstrated more extensive involvement, with bipolar foci (30.0%) or diffuse footplate manifestations (20.0%) more common. Acoustic reflexes were characteristically absent.

CONCLUSIONS

While HRCT may aid in the diagnosis of otosclerosis and rule out concomitant pathology in certain cases of clinical uncertainty or unexplained symptoms, its sensitivity for otosclerosis remains low. HRCT should not be relied upon to diagnose routine fenestral otosclerosis.

Role of MRI as first-line modality in the detection of previously undiagnosed otosclerosis: a single tertiary institute experience

Background

Otosclerosis causes conductive, sensorineural and mixed hearing loss (CHL, SNHL, MHL) and tinnitus in young adults. It is best diagnosed on high-resolution CT (HRCT). Occasionally, patients presenting with SNHL and/or tinnitus may undergo temporal bone MRI as the first investigation. In this study, we have described the role of MRI as the first-line modality in the detection of previously undiagnosed otosclerosis.

Using search words ‘MRI otosclerosis’ we found 15 cases in the PACS of our institute, (University Hospitals, KU Leuven, Belgium) from 2003 to 2018. Of these, 2 were known cases of otosclerosis, hence excluded from the study. The remaining 13 patients underwent MRI as first-line investigation for unilateral SNHL (8/13), bilateral SNHL (3/13), unilateral MHL (1/13) and bilateral pulsatile tinnitus (1/13). All MRI studies were reported by the same senior radiologist.

Results

Of these 13 cases, 12 were reported as showing MRI features suspicious for otosclerosis. The typical positive findings in these cases were intermediate T1 signal and post-contrast enhancement in the perilabyrinthine/pericochlear regions. Out of 13 patients, 9 underwent subsequent HRCT, confirming otosclerosis in all. The single MRI which was reported as normal initially showed otosclerosis on HRCT. Retrospective evaluation of this MRI study showed subtle positive findings of otosclerosis.

Conclusion

The end point of this study was to validate the subtle findings of otosclerosis on MRI, by comparison to the gold-standard modality HRCT. Our hypothesis is that in the appropriate clinical setting, familiarity with MRI features of otosclerosis would increase the diagnostic ‘catch’ in the first ‘net’ itself i.e. first-line MRI.

Diagnostic utility of labyrinth capsule bone density in the diagnosis of otosclerosis with high resolution tomography

OBJECTIVE

The aim of this study is to compare the bone density around the otic capsule in otosclerotic patients with a control group, and find the cut-off values of bone density from which we can diagnose the disease.

MATERIAL AND METHODS

A retrospective case-control study was performed. Bone densities in Hounsfield units (HU) from 28 otosclerotic ears were compared to the densities of 33 non otosclerotic capsules. These densities were measured in eight regions of interest (ROI) where the otosclerotic foci are usually found. The mean density of these regions (PROMED) was taken. Furthermore, the ROC curves of each ROI and the mean density (PROMED) were calculated.

RESULTS

All radiological densities in HU of each ROI and the mean density in otosclerotic patients were lower compared to non otosclerotic ears. The area under the ROC curve of each ROI and the mean density showed that the areas with greater accuracy for the diagnosis of otosclerosis were mean density, the fissula ante fenestram, and precochlear region, with cut-off values of 1980HU, 1750HU and 2114HU, respectively.

CONCLUSION

The mean density of the otic capsule (PROMED), the density in the fissula ante fenestram (ROI1) and in the precochlear region (ROI3) seem to be the most useful parameters to make a diagnosis of otosclerosis.

Involvement of the Internal Auditory Canal in Subjects With Cochlear Otosclerosis: A Less Acknowledged Third Window That Affects Surgical Outcome

OBJECTIVE

To investigate the effects of cavitating lesions involving the internal auditory canal (IAC) in subjects with cochlear otosclerosis with regard to poststapedotomy hearing outcome.

STUDY DESIGN

Retrospective study.

SETTING

Tertiary referral center.

PATIENTS

A retrospective chart review of 134 subjects with otosclerosis treated from January 2011 to June 2017 at Seoul National University Bundang Hospital was conducted. Sixteen subjects (23 ears) with temporal bone computed tomography (TBCT)-confirmed cochlear otosclerosis who underwent stapedotomy were included in the study.

MAIN OUTCOME MEASURES

Pure tone audiometry (PTA) (i.e., air and bone conduction; AC and BC, respectively) thresholds and air-bone gap (ABG), measured at 6 months postoperatively were compared between cochlear otosclerosis with and without IAC involvement (IAC group and non-IAC group, respectively).

RESULTS

A total of 14 of 23 ears showed involvement of the IAC. There were no significant differences in age, side of otosclerosis, or preoperative hearing threshold between the two groups. The mean postoperative AC and BC thresholds and ABG of the IAC group were significantly poorer (45.7 dB, 33.8 dB, and 11.8 dB, respectively) than those of the nonIAC group (24.1 dB, 20.0 dB, and 4.1 dB, respectively).

CONCLUSIONS

Cochlear otosclerosis with cavitating lesions involving the IAC showed significantly poorer postoperative audiological outcomes than those without any cavitating lesion. Cavitation extending to the IAC may act as a third window providing a route for sound energy shunting, and thus precluding successful hearing outcome in some subjects with cavitating otosclerosis after stapedotomy.

A Study of Wideband Energy Reflectance in Patients with Otosclerosis: Data from a Chinese Population

Objective(s)

The purpose of this study was to explore the effectiveness of wideband acoustic immittance (WAI) in the diagnosis of otosclerosis by comparing the differences in the energy reflectance (ER) of WAI between patients with otosclerosis and age- and gender-matched normal hearing controls in the Chinese population.

Methods

Twenty surgically confirmed otosclerotic ears were included in the otosclerotic group. The ER of WAI at ambient and peak pressures, resonance frequency, and 226-Hz tympanogram were collected prior to surgery using a Titan hearing test platform (Interacoustics A/S, Middelfart, Denmark). All diagnoses of otosclerosis in the tested ear were confirmed by surgery after the measurements. Thirteen normal adults (26 ears) who were age- and gender-matched with the otosclerotic patients were included as the control group.

Results

At peak pressure, the ERs of otosclerotic patients were higher than those of the control group for frequencies less than 4,000Hz and were lower for frequencies greater than 4,000Hz. In addition, within the analyzed frequencies, the differences observed at 2,520Hz was statistically significant (p<0.05/16=0.003, Bonferroni corrected). At ambient pressure, the differences observed at 1,260 and 6,350Hz were statistically significant (p<0.05/16=0.003, Bonferroni corrected). Although the differences between the otosclerotic and control groups exhibited similar trends to those in studies implemented in Caucasian populations, the norms in the present study in the control group were different from those in the Caucasian populations, suggesting racial differences in WAI test results. Regarding the middle ear resonance frequency, no significant difference was observed between the two groups (P>0.05).

Conclusion

WAI can provide valuable information for the diagnosis of otosclerosis in the Chinese population. Norms and diagnostic criteria corresponding to the patient's racial group are necessary to improve the efficiency of WAI in the diagnosis of otosclerosis.

"Third Window" and "Single Window" Effects Impede Surgical Success: Analysis of Retrofenestral Otosclerosis Involving the Internal Auditory Canal or Round Window

Background and Objectives: We aimed to identify prognostic computed tomography (CT) findings in retrofenestral otosclerosis, with particular attention paid to the role of otosclerotic lesion area in predicting post-stapedotomy outcome. Materials and Methods: We included 17 subjects (23 ears) with retrofenestral otosclerosis who underwent stapedotomy. On preoperative CT, the presence of cavitating lesion and involvement of various subsites (cochlea, round window [RW], vestibule, and semicircular canal) were assessed. Pre- and post-stapedotomy audiometric results were compared according to the CT findings. The surgical outcomes were analyzed using logistic regression with Firth correction. Results: Cavitating lesions were present in 15 of 23 ears (65.2%). Involvement of the RW was the strongest predictor of unsuccessful surgical outcome, followed by involvement of the internal auditory canal (IAC) and the cochlea. Conclusions: RW and IAC involvement in retrofenestral otosclerosis were shown to predict unsuccessful outcomes. While a “third window” effect caused by extension of a cavitating lesion into the IAC may dissipate sound energy and thus serve as a barrier to desirable postoperative audiological outcome, a “single window” effect due to an extension of retrofenestral otosclerosis into the RW may preclude a good surgical outcome, even after successful stapedotomy, due to less compressible cochlear fluid and thus decreased linear movement of the piston.

High-Resolution Computed Tomography of the Inner Ear: Effect of Otosclerosis on Cochlear Aqueduct Dimensions

OBJECTIVES

The cochlear aqueduct is a bony duct connecting the scala tympani with the subarachnoid space. Given the pathophysiology of otosclerosis, including bone resorption and new bone deposition, we hypothesize that the cochlear aqueduct in otosclerotic ears is narrowed.

METHODS

A retrospective review of patients with otosclerosis who have undergone high-resolution computed tomography (HRCT) of the temporal bone was completed. The control cohort included 20 patients with the diagnosis of noise-induced hearing loss, without the diagnosis of otosclerosis. Uniform measurements of cochlear aqueduct dimensions were performed using the axial plane.

RESULTS

The otosclerosis cohort included 25 males and 52 females with mean age of 52.2 ± 17.6 years. The control group included 10 males and 10 females with mean age of 64.0 ± 18.5 years. The mean cochlear aqueduct length, width mid canal, aperture base, aperture widest diameter, and funnel diameter in millimeters were 12.19 ± 1.66, 0.68 ± 0.28, 4.21 ± 1.67, 3.23 ± 1.47, and 2.70 ± 1.05 in the ears with otosclerotic foci and 11.57 ± 1.66, 0.69 ± 0.29, 2.56 ± 1.59, 2.77 ± 1.67, and 2.58 ± 1.03 in control group, respectively. Statistical difference was seen in length of cochlear aqueduct, aperture base, and aperture widest diameters (P = .017, <.001, .007).

CONCLUSIONS

The length of the cochlear aqueduct and the funnel width are statistically longer in the otosclerotic population compared to control. The width of the cochlear aqueduct is not statistically different.

Otosclerosis: anatomical distribution of otosclerotic loci analyzed by high-resolution computed tomography

PURPOSE

To clarify the anatomical distribution of otosclerotic loci in otosclerosis.

METHODS

Ninety-five patients with surgically confirmed uni- or bilateral otosclerosis were enrolled into the study. Hypodense areas observed in the otic capsule by high-resolution computed tomography (HRCT) were defined as otosclerotic loci. The location and number of lesions were examined, and the probability of lesion overlap and correlation with age/hearing parameters (air and bone conduction threshold, air-bone gaps) were tested.

RESULTS

Otosclerotic loci were confirmed by HRCT in 77 out of 115 operated ears. The three commonly affected sites were the anterior part of the oval window (ant-OW), anterior part of the internal auditory canal (ant-IAC), and pericochlear area (PCochA), with lesions detected in 96.1%, 46.8%, and 26.0% of ears, respectively. Only the ant-OW area was affected in 48.1% of the ears; the ant-IAC in 3.9%; and PCochA in none with significant differences (p < 0.01). The ant-OW lesions preferentially overlapped with ant-IAC (44.6%) than PCochA lesions (27.0%) (p < 0.05). Among double sites diseases, triple sites diseases occurred more commonly in the ant-OW + PCochA group (80%) than ant-OW + ant-IAC group (48.5%) (p < 0.05). There was no correlation between a number of lesions and age/hearing parameters.

CONCLUSIONS

Based on the probability of lesion overlap, otosclerotic lesions may initiate at ant-OW followed by ant-IAC and later PCochA. Although the number of lesions showed no immediate correlation with hearing level or age, anatomical stage of the disease estimated by the location and the number of otosclerotic loci could be useful in predicting the future hearing status.

Wideband tympanometry and absorbance measurements in otosclerotic ears

OBJECTIVES

This study aimed to assess absorbance using a thorough analysis of individual points of its plot in ears with intraoperatively confirmed otosclerosis. To the best of our knowledge, until recently no analyses have been performed that concerned the shape of an absorbance plot and a detailed analysis of its individual points. This study is the first to undertake such an issue.

METHODS

A total of 77 otosclerotic ears were included in the study. Pure tone audiometry, low frequency tympanometry, and wide band tympanometry including absorbance were performed preoperatively. The average patients' age in the group was 43.49 years (standard deviation = 10.44). Individual points of absorbance plot were thoroughly analyzed. Parameters were analyzed, such as resonance frequency; number of peaks; maximum absorbance (Height); and plot Width at the following Heights: 1/3, 1/2, and 2/3 (Width1/3, Width1/2, Width2/3, respectively), as well as associated absorbance parameters and frequencies.

RESULTS

Data analysis revealed five different types of absorbance plots. Numerous statistically significant differences regarding the parameters of individual points of the plots were found among the distinguished types.

CONCLUSIONS

There are five types of absorbance plots in otosclerotic ears: type I, characterized by two distinct peaks, closely resembling normal ear absorbance plot; type II with a single distinct peak reaching high values of absorbance; type III with reduced absorbance for frequencies <2000 Hz; type IV with reduced absorbance for all frequencies; and type V with reduced absorbance for frequencies >2000 Hz. Absorbance measurements may play an important role in the diagnostics of otosclerosis; however, further research is necessary in this area.

LEVELS OF EVIDENCE

4 Laryngoscope, 129:E365-E376, 2019.

Otosclerosis and Dysplasias of the Temporal Bone

Many bone dysplasias, some common and others rare, may involve the temporal bone causing conductive, sensorineural, or mixed hearing loss, vestibular dysfunction, or skull base foraminal narrowing, potentially affecting quality of life. Some conditions may affect only the temporal bone, whereas others may be more generalized, involving different regions of the body. High-resolution computed tomography may detect subtle osseous changes that can help define the type of dysplasia, and MR imaging can help define the degree of activity of lesions and potential associated complications.

Impact of Imaging in Management of Otosclerosis

The use of imaging in otosclerosis for diagnosis, preoperative assessment, and follow-up has the potential to give the clinician an additional tier of patient evaluation and validation of diagnosis. Before stapes surgery, imaging may help avoid unnecessary middle ear explorations in nonotosclerotic cases, prevent potential complications, and assist in appropriate patient counseling regarding management expectations. Postoperatively, following unsuccessful air-bone gap closure in stapes surgery or conductive hearing deterioration following initial successful closure of the air bone gap, imaging can be used to determine the prosthesis position in the middle ear.

Importance of a dedicated neuroradiologist in reporting high-resolution computed tomography for otosclerosis: a retrospective comparison study of 40 patients

OBJECTIVES

This study aimed to compare the reporting of high-resolution computed tomography of temporal bones for otosclerosis by general radiologists and a neuroradiologist within a local National Health Service Trust.

METHODS

A retrospective case review of 36 high-resolution temporal bone computed tomography images obtained between 2008 and 2015 from 40 otosclerosis patients (surgically confirmed) was performed in a district general hospital setting. The main outcome measures were correct identification of otosclerosis by high-resolution computed tomography and adherence to the petrous temporal bone imaging protocol.

RESULTS

Correct diagnosis rates were significantly different when made by general radiologists vs a neuroradiologist (p < 0.0001; two-tailed Fisher's exact test). None of the high-resolution computed tomography scans adhered to the temporal bone imaging protocol.

CONCLUSION

The use of high-resolution computed tomography for suspected otosclerosis is helpful for diagnosis, disease staging, obtaining informed consent, surgical planning and prognosis. This study suggests that radiological detection of otosclerotic changes by high-resolution computed tomography of the temporal bone is significantly better when performed by a dedicated neuroradiologist than by a general radiologist. Use of a standardised temporal bone computed tomography protocol is recommended to provide consistently high-quality images for maximising disease detection.

[The application of stapedoplasty for the treatment of hearing loss in the patients suffering from obliterative otosclerosis]

This article presents the results of analysis of the data obtained during the examination and the surgical treatment of the patients presenting with the obliterative form of otosclerosis and suffering from hearing impairment with special reference to the intraoperative findings, technical aspects of stapedoplasty, and its effectiveness. A total of 14 patients (17 ears) were recruited for the participation in the present study including 10 women at the mean age of 38.8±6.2 years and 4 men (mean age 44.8±3.9 years). The duration of the hearing loss in the period preceding the surgical treatment in 7 (50%) patients was more than 8 years. According to the results of tonal threshold audiometry (TTA), the mean bone conduction (BC) threshold for conductive hearing loss in the frequency range from 0.5 to 4.0 kHz was 24.9±8.1 dB with the mean bone air gap (BAG) equaling 38±5.1 dB. Computed tomography (CT) of the temporal bones revealed grade 1 obliterative otosclerosis in 4 patients, grade II of the same condition in 6 patients, and grade III in 7 ones. These findings were confirmed intraoperatively. In 15 cases, stapedostomy was carried out with the use of the non-contact CO2 laser-based system, in the remaining cases a microdrill was employed. Five patients underwent laser-assisted piston stapedoplasty while in 11 others the stapes prosthesis was placed on the autovein. One patient was treated by the same method with the use of the autocartilaginous prosthesis. The functionally acceptable results within 1 year after the surgical intervention were obtained in all the treated patients with the mean bone air gap equaling 13.2±3.4 dB. The best outcome (the reduction of the BC threshold and BAG by 7 dB and 25.9 db on the average respectively within 1 year after surgery was achieved in the patients with grade III obliterative otosclerosis.

Diagnostic efficacy and therapeutic impact of computed tomography in the evaluation of clinically suspected otosclerosis

OBJECTIVE

To assess the diagnostic efficacy and therapeutic impact of CT in evaluating patients with clinically suspected otosclerosis.

METHODS

CT scans performed over a 5-year period for clinically suspected otosclerosis were retrospectively reviewed. CT diagnoses were correlated with subsequent surgical management. For otosclerosis positive cases, clinically significant extensions of otosclerosis were correlated with audiometry and the diagnosis was correlated with surgical findings.

RESULTS

Of 259 CT studies, 46 % of patients were positive, 49 % negative and 5 % equivocal for otosclerosis. A relevant alternative CT diagnosis was evident in 33 % of the negative studies. One targeted surgery was performed for every four CT studies. CT outcome influenced the decision to perform stapedectomy in 41 % CT-positive versus 4 % CT-negative patients. CT-positive ears for otosclerosis could not be predicted from baseline clinical or audiometric criteria. Those with endosteal extension demonstrated lower bone conduction thresholds presurgically. The positive predictive value of CT diagnosis of otosclerosis was 100 %.

CONCLUSIONS

CT demonstrated a high rate of clinically relevant diagnoses in both CT-positive and -negative for otosclerosis patients, and this frequently influenced surgical management. CT also added value by demonstrating relevant extensions of the otosclerotic foci, some of which were predictive of audiometric parameters.

KEY POINTS

• CT demonstrates a high rate of alternative diagnoses in suspected otosclerosis, 1:3. • CT results in a high rate of targeted surgery in suspected otosclerosis, 1:4. • CT prevents exploratory surgery in suspected otosclerosis. • Endosteal extension of otosclerosis is predictive of lower bone conduction tresholds presurgically. • The PPV of CT diagnosis of otosclerosis was 100 %.

Obliquity of the Stapes in Otosclerosis: A New Radiological Sign

Introduction Observing the obliquity of stapes by closely scrutinizing the HRCT temporal bone in otosclerosis revealed a reliable and consistent finding. This finding can add to the existing radiological criteria in diagnosis of otosclerosis.

Objective The objective of this study is to establish the obliquity of stapes in otosclerosis by radiological measurements using HRCT temporal bone by comparing: (a) the distance between the horizontal (tympanic) segment of facial nerve and stapes head in otosclerotic ears (study group) with non-otosclerotic ears (control group); and (b) the angle subtended by stapes with promontory in the study and control groups.

Methods This is a prospective study performed after the institutional Ethics Committee clearance (IEC 3/2013).

Results An increased mean distance between the horizontal segment of facial nerve and stapes head in otosclerotic patients (i.e., 2.49mm +/− 0.24mm SD), when compared with the non-otosclerotic patients (i.e., 1.46mm +/− 0.16mm SD) is noted. There is a change in angle (i.e., 64.550 +/− 7.190 SD) subtended by the stapes toward the promontory in otosclerotic ears when compared with that of controls (i.e., 99.700 +/− 40 SD). We applied the Mann-Whitney U non-parametric test and considered p value of < 0.0001 highly significant.

Conclusions Obliquity of stapes in otosclerosis referred to as a “Pisa” sign by the senior author has diagnostic value as a new radiological sign in imaging of otosclerosis. This obliquity explains the torsional effect of otosclerosis on the ossicular chain. The findings correlate with late complications and failures in stapes surgery.

Stapedotomy and its effect on hearing - our experience with 54 cases

INTRODUCTION

This study reviews the cases of stapedotomy and evaluates its effectiveness at improving hearing loss in patients with otosclerosis.

MATERIALS AND METHODS

Retrospective review of patients' records who had clinical and audiometric diagnosis of otosclerosis from January to December 2012.

RESULTS

A total of 54 stapedotomy surgeries (52 unilateral and 1 bilateral surgeries) were received. Average post-operative ABG for 0.5, 1, 2 and 4 KHz showed that 61.1% had complete closure of ABG ( ABG < 10 dB) compared with 1.6% preoperatively and 85.2% had closure of ABG to within 20dB compared with 4.7% preoperatively (t - 13.89, p = 0.000). More than 94% had hearing improvement and 81.5% had ABG closure greater than 10 dB postoperatively (mean gain 23.38 ± 12.37, t = 13.89, p = 0.000). A total of 13% complications were recorded with TM perforation (5.6%) being the commonest complication.

CONCLUSION

Stapedotomy is an effective surgical procedure for the treatment of otosclerosis which leads to improvement in patients' quality of life. A favorable hearing outcome can be obtained by the combination of experienced hands with minimal surgical trauma and appropriate surgical technique.

Audiometric Results after Stapedotomy Operations in Patients with Otosclerosis and Preoperative Small Air-Bone Gaps

Objectives: The efficacy of stapedotomies performed on patients with small air-bone gaps (<25 dB) was compared with the efficacy of the operation in patients who had otosclerosis with high air-bone gaps (≥25 dB). Methods: This retrospective study evaluates the short-term postoperative air and bone conduction thresholds and air-bone gaps after 182 CO2 laser stapedotomies. Results: A significantly smaller air-bone gap and lower air conduction thresholds after surgery were observed in the group of patients who underwent surgery with preoperative air-bone gaps of less than 25 dB. Bone conduction thresholds improve in the group with small air-bone gaps after surgery. Conclusions: The results after stapedotomies are good even if the preoperative air-bone gap is small and the overall risk of hearing deterioration due to stapes surgery remains low.

Factors affecting postoperative outcome in otosclerosis patients: Predictive role of audiological and clinical features

OBJECTIVE

Factors affecting postoperative hearing results of patients with otosclerosis were analyzed.

METHODS

Included were 191 patients with otosclerosis in whom 234 primary stapes surgeries were performed from August 1991 to December 2011 by one surgeon in three tertiary hospitals. Evaluation of factors affecting postoperative hearing thresholds at individual frequencies were performed by logistic regression analysis.

RESULTS

Closure of the air-bone gap (ABG) after surgery was good at 2kHz, but poor at 4kHz and frequencies under 1kHz. In addition, improvement at 8kHz was worse than that at any other frequency. Multivariate logistic regression analysis by the stepwise method showed that under the mean preoperative ABG (odds ratio [OR]=2.42), unilaterality (OR=2.53) and male sex (OR=2.65) were significantly better prognostic factors at 250Hz. At 500Hz, under mean preoperative ABG (OR=2.56) was the significantly better factor. No significant factors were found at 1kHz. Cochlear otosclerosis (OR=3.57) was a significantly worse prognostic factor at 2kHz. Under mean preoperative ABG (OR=2.82) and younger age (OR=1.03) were significantly better prognostic factors at 4kHz. At 8kHz, worse preoperative air conduction threshold (OR=1.96) was a significantly better prognostic factor.

CONCLUSION

Preoperative ABG, preoperative air conduction threshold, cochlear otosclerosis, male sex, laterality and age were significant prognostic factors for postoperative hearing outcome in otosclerosis patients. Especially, preoperative ABG was a significant prognostic factor at multiple frequencies. We suppose that patients with larger preoperative ABG have some other otosclerotic lesions outside the oval window niche.

The role of imaging in the diagnosis and management of otosclerosis

OBJECTIVE

To examine the evidence for the role of radiologic imaging in the diagnosis and management of otosclerosis.

DATA SOURCES

A review of contemporary (1990 to present) English medical literature via MedLine using the terms imaging, otosclerosis, otospongiosis, stapes surgery, computed tomography, magnetic resonance, CT, and MRI was performed.

STUDY SELECTION

Abstracts were reviewed independently by 2 authors and relevant articles were then evaluated. Exclusion criteria included editorials, non-English language, comments, and letters.

DATA EXTRACTION

Level of evidence was assigned in accordance with the Oxford Centre for Evidence-based Medicine guidance (Levels I-V).

RESULTS

Thirty-seven articles met the inclusion criteria, of which, 11 were of Level III, 22 of Level IV, and 4 of level V evidence. High-resolution computed tomography (CT) of the temporal bones is the imaging technique of choice in the diagnosis of otosclerosis with newer multidetector scanners demonstrating a sensitivity and specificity in excess of 90%. There is Level III evidence that CT densitometry and extent of disease on CT correlates with hearing thresholds. Extensive and multifocal disease on CT has a poorer prognosis (Level III/IV). The potential use of CT in staging classifications, surgical planning, predicting surgical outcomes and risk of complications has also been described and evaluated.

CONCLUSION

This systematic review indicates that imaging has a useful role in both the diagnosis and management of otosclerosis, supported principally by Level III/IV evidence.

Imaging in otosclerosis: A pictorial review

Otosclerosis is an otodystrophy of the otic capsule and is a cause of conductive, mixed or sensorineural hearing loss in the 2nd to 4th decades of life. Otosclerosis is categorised into two types, fenestral and retrofenestral. Imaging plays an important role in the diagnosis and management of otosclerosis. High-resolution CT (HRCT) of the temporal bone using 1-mm (or less) thick sections is the modality of choice for assessment of the labyrinthine windows and cochlear capsules. MRI has limited application in the evaluation of the labyrinthine capsules but is useful for assessment of the cochlear lumen prior to cochlear implantation in patients with profound hearing loss. The treatment of fenestral otosclerosis is primarily surgical with stapedectomy and prosthesis insertion. Patients with retrofenestral otosclerosis and profound hearing loss are treated medically using fluorides, but may derive significant benefit from cochlear implantation. This pictorial review aims to acquaint the reader with the pathology and clinical features of otosclerosis, the classical imaging appearances on CT and MRI, a radiological checklist for preoperative CT evaluation of otosclerosis, imaging mimics and a few examples of post-stapedectomy imaging and complications. Teaching points • Otosclerosis causes conductive, sensorineural and mixed hearing loss in adults.• HRCT of the temporal bone is the diagnostic imaging modality of choice.• Stapedectomy is used to treat fenestral otosclerosis.• Fluorides and cochlear implantation are used to treat retrofenestral otosclerosis.

Contribution of Vestibular-Evoked Myogenic Potential (VEMP) testing in the assessment and the differential diagnosis of otosclerosis

Background

The aim of this prospective clinical study was to evaluate the clinical importance of Vestibular-Evoked Myogenic Potentials (VEMPs) in the assessment and differential diagnosis of otosclerosis and otologic diseases characterized by “pseudo-conductive” components. We also investigated the clinical appearance of balance disorders in patients with otosclerosis by correlating VEMP results with the findings of caloric testing and pure tone audiometry(PTA).

Material/Methods

Air-conducted(AC) 4-PTA, bone-conducted(BC) 4-PTA, air-bone Gap(ABG), AC, BC tone burst evoked VEMP, and calorics were measured preoperatively in 126 otosclerotic ears.

Results

The response rate of the AC-VEMPs and BC-VEMPs was 29.36% and 44.03%, respectively. Statistical differences were found between the means of ABG, AC 4-PTA, and BC 4-PTA in the otosclerotic ears in relation to AC-VEMP elicitability. About one-third of patients presented with disequilibrium. A statistically significant interaction was found between calorics and dizziness in relation to PTA thresholds. No relationship was found between calorics and dizziness with VEMPs responses.

Conclusions

AC and BC VEMPs can be elicited in ears with otosclerosis. AC-VEMP is more vulnerable to conductive hearing loss. Evaluation of AC-VEMP thresholds can be added in the diagnostic work-up of otosclerosis in case of doubt, enhancing differential diagnosis in patients with air-bone gaps. Otosclerosis is not a cause of canal paresis or vertigo.

Audiometric evaluation after stapedotomy with Fisch titanium prosthesis

Otosclerosis causes the fixation of the stapes and conductive hearing loss, usually corrected with the use of hearing aids or through stapedotomy and the replacement of the involved stapes with a prosthesis. Titanium has been the most recently used material of choice in stapedotomy prostheses. Only two prostheses are commercially available in Brazil. There are no reports in the literature on the Fisch-type Storz titanium stapes piston prosthesis.

OBJECTIVE

This retrospective study aims to look into the auditory outcomes of patients submitted to stapedotomy and titanium stapes piston prosthesis implantation.

METHOD

The criteria described by the American Academy of Otolaryngology were used to compare pre and postoperative air-bone gaps seen in audiometry tests.

RESULTS

The mean low-frequency postoperative air-bone gap was 12.9 dB; the mean high-frequency air-bone gap was 5.2 dB (mean 9.1 dB); median gap was 8.8 dB, with a minimum of 1.3 dB and a maximum of 21.6 dB; standard deviation was 5.7 dB, and p < 0.001. Twenty-five (75.8%) patients had air-bone gaps of 10 dB and under; 32 (96.9%) patients had gaps of 20 dB and under; and all patients had gaps of 30 dB and under.

CONCLUSION

The Fisch-type titanium stapes piston prosthesis presented outcomes consistent with the literature and can be used safely in stapedotomy procedures.

High resolution computed tomography in stapedial otosclerosis

The value of high-resolution CT scanning in diagnosing stapedial otosclerosis and in influencing surgical planning was studied. 40 cases, consisting of patients of both genders, above the age of 14 years, with a clinical diagnosis of otosclerosis underwent HRCT of the temporal bones. Images were acquired in axial plane, with a bone algorithm, keeping slice thickness at 0.5 mm and intervals of 0.5 mm. Reconstruction of the volume data set was done to obtain overlapping slices in various planes, so as to obtain the best possible images of the footplate of stapes. The thickness of the footplate was measured and the site of lesion was noted in these images. On exploratory tympanotomy, the footplate was assessed and graded according to a visual scale. HRCT was able to diagnose stapedial otosclerosis in 85% ears. It was able to identify the presence of a thickened footplate correctly with a sensitivity of 85.3% (P value 0.16). It was able to correctly localize the site of otosclerotic focus in 85% cases (P value <0.01). Thus, an estimate of the thickness of the footplate likely to be encountered and thus the amount of drilling likely to be required to create a fenestra; and the likely site of maximum thickness could be made pre-operatively. This study also established the value of multislice CT on the acquisition of such data. This method obviates the requirement of difficult patient positioning, reduces scanning time; while greatly improving the sensitivity of the scanning.

Computed tomography and otosclerosis: a practical method to correlate the sites affected to hearing loss

OBJECTIVES

We present a practical method for correlating computed tomography (CT) scans with hearing loss in otosclerosis.

METHODS

We reviewed the CT scans of 18 patients (34 ears) with clinical otosclerosis who were seen between 2007 and 2008. The scans were reviewed by an otologist in a clinical office setting, followed by a blinded radiologist working at an imaging workstation. The 5 most commonly affected sites in otosclerosis were evaluated for evidence of otospongiosis and then correlated with the degree of air-bone gap and sensorineural hearing loss.

RESULTS

Positive CT findings were noted in 70.5% of ears, with a 94% concordance between readings. The sites affected included the ante fenestram (21 ears), round window niche (12), cochlear promontory (4), cochlear apex (3), and posterior fenestram (2). The average air-bone gap increased with each additional site of involvement within an otic capsule (p = 0.004). The bone conduction threshold also increased, on average, with each additional affected site (p = 0.047).

CONCLUSIONS

Most patients with clinical evidence of otosclerosis have evidence of otosclerosis on CT that is readily detected in the office setting. Ears with more affected sites have a significantly greater degree of air-bone gap and sensorineural hearing loss.

Relationship between high-resolution computed tomography densitometry and audiometry in otosclerosis

OBJECTIVE

The aim of this study is to evaluate the usefulness of high-resolution computed tomography (HRCT) densitometry in the diagnosis of otosclerosis and to investigate the relationship between CT densitometry and audiometry.

METHODS

HRCT findings and audiometry were compared among 34 patients (34 ears, the otosclerosis group) with surgically confirmed otosclerosis between January 2007 and December 2007 and 33 patients (33 opposite normal ears, the control group) with facial paralysis diagnosed at the same period of time. Seven regions of interest (ROI) were set manually around the otic capsule on the axial slice of 0.75-mm-thick CT image. The mean CT values of these seven regions were measured. In each ROI, the mean CT value of the otosclerosis group and that of the control group were compared. Based on the CT findings, the ears with otosclerosis were classified into two groups: Group A showed no pathological CT findings; Group B showed low density around the cochlea. In the otosclerosis group, the relationship between the findings of CT and the results of audiometry was analyzed.

RESULTS

The mean CT values in the area posterior to the oval window and anterior to the oval window were significantly lower for the otosclerosis group compared with the control group (the former t=-2.030, p=0.046; the latter Z=-4.979, p<0.01). Group A consisted of 30 patients, 7 of which (23.33%) exhibited conductive hearing loss, and 23 of which (76.67%) exhibited mixed hearing loss; Group B had 4 patients, all with mixed hearing loss. For the otosclerosis group, the mean CT value in the area posterior to the oval window was positively correlated with the mean air conduction threshold (r=0.4273, p=0.0117) and with the mean air-bone gap (r=0.3995, p=0.0192).

CONCLUSION

Quantitative evaluation of CT with slices less than 1mm in thickness may provide important information for the diagnosis and assessment of otosclerosis which are unattainable through other methods.