In response to letter to the editor: "Correlation of computed tomography with histopathology in otoslcerosis", Quesnel et al. Otol Neurotol 2013; 34(1):22-8

A comparison between endoscopic and microscopic approaches for stapes surgery: experience of a tertiary referral center

PURPOSE

Otosclerosis is a common ear disease causing ankylosis of the stapedio-vestibular joint and conductive hearing loss. Stapedoplasty is the most advisable surgical solution. The restoration of hearing depends on the condition of the patient and the surgery itself. The aim of our work was to compare the surgical and audiological results of stapedoplasty performed with endoscopic versus microscopic technique.

METHODS

This is a retrospective study of 254 patients treated with stapedoplasty with a microscopic approach (91/254) or with an endoscopic approach (163/254) between 2014 and 2021 at our tertiary referral center. Statistical significance of differences between the two methods was determined using the Mann-Whitney test for quantitative variables and the Wilcoxon matched-pairs signed-rank test for repeated measures. Categorical variables were assessed with Fisher's exact test.

RESULTS

Both techniques improved the hearing status of patients, with no statistically significant difference between them. There was also no statistically significant difference in reported complications between the two techniques. There is a statistical difference (p < 0.001) in operating time between the two techniques: the endoscopic technique had a mean operating time of 39 min versus 45 min for the microscopic technique.

CONCLUSIONS

The two techniques are comparable in terms of results and the choice depends on the surgeon's preferences and experience.

Patterns of Signal Intensity in CISS MRI of the Inner Ear and Eye

BACKGROUND

Constructive interference in steady state (CISS) is a gradient echo magnetic resonance imaging (MRI) pulse sequence that provides excellent contrast between cerebrospinal fluid and adjacent structures but is prone to banding artifacts due to magnetic field inhomogeneities. We aimed to characterize artifacts in the inner ear and eye.

METHODS

In 30 patients (60 ears/eyes) undergoing CISS sequence MRI, nine low-signal intensity regions were identified in the inner ear and compared to temporal bone histopathology. The number and angle of bands across the eye were examined.

RESULTS

In the cochlea, all ears had regions of low signal corresponding to anatomy (modiolus (all), spiral lamina (n = 59, 98.3%), and interscalar septa (n = 50, 83.3%)). In the labyrinth, the lateral semicircular canal crista (n = 42, 70%) and utricular macula (n = 47, 78.3%) were seen. Areas of low signal in the vestibule seen in all ears may represent the walls of the membranous utricle. Zero to three banding artifacts were seen in both eyes (right: 96.7%, mean 1.5; left: 93.3%, mean 1.3).

CONCLUSION

Low signal regions in the inner ear on CISS sequences are common and have consistent patterns; most in the inner ear represent anatomy, appearing blurred due to partial volume averaging. Banding artifacts in the eye are more variable.

Brazilian Society of Otology task force - Otosclerosis: evaluation and treatment

OBJECTIVES

To review and provide evidence-based recommendations for the diagnosis and treatment of otosclerosis.

METHODS

Task force members were educated on knowledge synthesis methods, including electronic database search, review and selection of relevant citations, and critical appraisal of selected studies. Articles written in English or Portuguese on otosclerosis were eligible for inclusion. The American College of Physicians' guideline grading system and the American Thyroid Association's guideline criteria were used for critical appraisal of evidence and recommendations for therapeutic interventions.

RESULTS

The topics were divided into 2 parts: 1) Diagnosis - audiologic and radiologic; 2) Treatment - hearing AIDS, pharmacological therapy, stapes surgery, and implantable devices - bone-anchored devices, active middle ear implants, and Cochlear Implants (CI).

CONCLUSIONS

The pathophysiology of otosclerosis has not yet been fully elucidated, but environmental factors and unidentified genes are likely to play a significant role in it. Women with otosclerosis are not at increased risk of worsening clinical condition due to the use of contraceptives or during pregnancy. Drug treatment has shown little benefit. If the patient does not want to undergo stapedotomy, the use of hearing aids is well indicated. Implantable systems should be indicated only in rare cases, and the CI should be indicated in cases of profound deafness.

Vertigo Associated with Otosclerosis and Stapes Surgery-A Narrative Review

Otosclerosis is a pathological condition affecting the temporal bone, and is characterized by remodelling of the labyrinthine bone tissue through a dynamic process of osteolysis and osteogenesis. This condition progressively leads to hearing loss, tinnitus, and vertigo. Stapedotomy, a surgical procedure involving the removal of the stapes superstructure and its replacement with a prosthesis, is the treatment of choice to improve hearing in individuals with otosclerosis. However, vestibular dysfunction is a significant complication associated with this procedure, which can occur intraoperatively or postoperatively, ranging from the immediate postoperative period to weeks, months, or even years after surgery. This paper aims to provide a comprehensive review of the most important causes of vertigo associated with otosclerosis and stapes surgery with the goal of minimizing the incidence of this complication. Understanding the underlying factors contributing to vertigo in this context is crucial for the prevention and effective management of vertigo in patients undergoing stapedotomy.

Missed Radiological Diagnosis of Otosclerosis in High-Resolution Computed Tomography of the Temporal Bone-Retrospective Analysis of Imaging, Radiological Reports, and Request Forms

Objectives: Several studies reported low detection rates of otosclerosis in high-resolution computed tomography (HRCT), especially when the scans were reviewed by non-specialized general radiologists. In the present study, we conducted a retrospective review of the detection of otosclerosis in HRCT by general radiologists and the impact of inadequately filled radiological request forms on the detection rate. Methods: Retrospective analysis of hospital records, HRCT reports, and radiological referral notes of 40 patients who underwent stapedotomy surgery for otosclerosis. HRCT imaging data sets were retrospectively reviewed by a blinded experienced neuroradiologist, whose reading served as the gold standard. Results: General radiologists reading HRCT scans had an overall detection rate of otosclerosis of 36.1% in this cohort (13 of 36 available HRCT reports). The neuroradiologist had a much higher detection rate of 82.5% (33 of 40 cases). Interobserver agreement between the general radiologists and the subspecialist neuroradiologist was poor (Cohen’s kappa κ = 0.26). General radiologists missed the diagnosis in 15 of the 33 CT-positive scans, corresponding to a missed diagnosis rate of 45.4%. There was a highly significant association between a missed diagnosis and the lack of an explicitly mentioned clinical suspicion of otosclerosis in the request forms (Pearson’s chi-squared test, p < 0.005). Conclusion: The diagnosis of otosclerosis is frequently missed by radiologists on HRCT scans of the temporal bone in a clinical setting. Possible reasons include a relative lack of experience of general radiologists with temporal bone imaging as well as the failure of clinicians to unambiguously communicate their suspicion of otosclerosis.

Computed Tomography Density as a Bio-marker for Histologic Grade of Otosclerosis: A Human Temporal Bone Pathology Study

HYPOTHESIS

Computed tomography (CT) density measurement can be used to objectively distinguish otosclerosis from normal bone and to determine histologic grades of otosclerosis.

BACKGROUND

Otosclerosis can be seen on CT as subtle radiolucent areas. An objective radiologic measurement that corresponds to known otosclerosis pathology may improve diagnostic accuracy, and could be used as a radiologic biomarker for otosclerosis grade.

METHODS

A blinded, randomized evaluation of both histologic grade on histopathology slides and CT density measurement was performed on 78 human temporal bone specimens (31 with otosclerosis and 47 controls) that had undergone high-resolution multi-detector CT before histologic processing. Assessments were performed at 11 regions of interest (ROIs) in the otic capsule for each specimen.

RESULTS

The CT density measurement mean (Hounsfield Units) ± standard deviation for all ROIs (Nos. 1-9) was 2245 ± 854 for grade 0 (no otosclerosis, n = 711), 1896 ± 317 for grade 1 (inactive otosclerosis, n = 109), and 1632 ± 255 for grades 2 and 3 combined (mixed/active otosclerosis, n 35). There was a strong inverse correlation of CT density to histologic grade at ROIs Nos. 1-5 (ANOVA, p < 0.0001). The inter-rater reliability for CT density was very good (correlation coefficient 0.87, p < 0.05). ROC curves suggested a cut-off of 2,150HU to distinguish otosclerosis from normal bone, and 1,811HU to distinguish low grade from mixed/high grade otosclerosis.

CONCLUSIONS

In human temporal bone specimens, CT density may be used to distinguish normal bone from bone involved by otosclerosis. A higher histologic grade (i.e., indicating a more active otosclerotic focus) correlated with lower density.

Cochlear Implantation in Advanced Otosclerosis: Pitfalls and Successes

Purpose of Review

This review will highlight recent outcome-based evidence guiding decision making for cochlear implantation in advanced otosclerosis, related complications, and technical surgical considerations in otosclerosis and the obstructed cochlea.

Recent Findings

Cochlear implantation in advanced otosclerosis results in consistent, excellent auditory outcomes with improvement in both objective speech recognition scores and subjective quality of life measures. Facial nerve stimulation may occur at higher rates in otosclerosis cochlear implant recipients. Cochlear implantation in the setting of luminal obstruction in osteosclerotic patients may be managed with altered surgical technique to achieve successful auditory improvements. Pre-operative imaging with high resolution CT or MRI may help anticipate intraoperative challenges and post-operative complications in cochlear implantation.

Summary

Cochlear implantation is an established, successful treatment for profound hearing loss in advanced otosclerosis. Surgeon knowledge of outcomes, complications, and potential surgical challenges is important to appropriately counsel patients regarding auditory rehabilitation options in advanced otosclerosis.

Audiologic Outcomes of Footplate Drillout for Obliterative Otosclerosis

OBJECTIVE

To evaluate the audiologic outcomes of microdrill fenestration for obliterative otosclerosis compared to traditional stapedotomy technique.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary referral center.

PATIENTS

Adult patients undergoing stapedotomy for otosclerosis.

MAIN OUTCOME MEASURES

Patients were separated into groups that underwent either microdrill or laser fenestration based on intraoperative severity of disease. Audiologic outcomes and complications were compared between the two groups.

RESULTS

There were 588 ears in 519 patients that were evaluated. There was a significant postoperative improvement in pure tone average, air-bone gap, and mean bone conduction thresholds for both the obliterative and nonobliterative group (p < 0.001). There was no significant difference in the pre- or postoperative hearing status between the two groups. There was no significant difference in complications between the two groups, including no cases of postoperative profound hearing loss in the drill fenestration group.

CONCLUSIONS

Audiologic outcomes are similar between microdrill fenestration and laser fenestration for otosclerosis. Pure tone average, air-bone gap, and mean bone conduction thresholds all improved postoperatively and were similar between groups.

The Diagnostic Yield of Cone-Beam Computed Tomography for Degenerative Changes of the Temporomandibular Joint in Dogs

Degenerative changes of the temporomandibular joint (DTMJ) may be diagnosed via cone - beam computed tomography (CBCT). However, despite advancement in CBCT imaging, correlation of DTMJ features identified on CBCT with gross and histological findings is currently limited. This study aimed to correlate CBCT findings of DTMJ of dogs with gross and histopathologic changes. Temporomandibular joints (TMJ) (n = 38) from fresh cadaver heads of asymptomatic dogs (n = 19) were examined radiologically, macroscopically, and microscopically. Association of CBCT - detected DTMJ changes with gross and histological findings were statistically evaluated via kappa statistics and ordinal logistic mixed-effects models. The radiological changes observed on CBCT included joint space narrowing, subchondral/cortical bone changes (i.e., erosions or lysis), osteophytes, and subchondral bone sclerosis. Upon macroscopic evaluation, the majority of examined specimens had mild changes with cartilage defects and osteophytes affecting <10% of the total articular surface area. Histopathologic changes comprised splitting and degeneration of the fibrous cartilage layers, subchondral bone exposure, subchondral bone sclerosis, focal subchondral bone lysis, and occasional cell death. Subchondral sclerosis was the most prevalent finding radiologically and histologically with a fair to excellent agreement. Importantly, the more severe the TMJ degenerative changes, the higher the agreement between CBCT and histology. Based on the correlative results of statistical analysis, CBCT was found to be a suitable modality to evaluate DTMJ.

Fetal development and growth of the fissula ante fenestram in the human ear

Since the fissula ante fenestram (FAF) is considered as a focus of otosclerotic lesion and a route of perilymph leakage, there are few description of prenatal development of the cartilaginous canal passing though the cochlear wall. We examined the sagittal and frontal histological sections of the ear from 32 human fetuses at 8-37 weeks of gestational age. At 8-12 weeks, in the immediately anterior side of a connection between the cochlear and canalicular parts of the otic capsule cartilage, the FAF appeared as a tear of a cartilage between the basal and second turns of the cochlea. The tear became a slit opening to the scala vestibuli. At 13-15 weeks, the FAF, less than 1.2 mm in length, had the anterosuperior and postero-inferior apertures: the former was near the geniculate ganglion and became closed after 15 weeks, while the latter approached the oval window. Third trimester fetuses, the FAF, 1.5-2.0 mm in length, consistently carried a single, postero-inferior aperture extending along the anterior margin of the oval window and it contained no definite epithelium and vessel. Although it was endochondral ossification, there was no clear zonation in cartilage cells of the FAF. A mechanical stress during three-dimensional coiling of the cochlear ducts seemed to provide the FAF. After the FAF was established, the stapes footplate might use a part of the inferior aperture for the syndesmosis. A specific ossification was seen in the FAF, but it might rarely cause the pathological syndesmosis.

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.

Current Trends, Controversies, and Future Directions in the Evaluation and Management of Superior Canal Dehiscence Syndrome

Patients with superior canal dehiscence syndrome (SCDS) can present with a range of auditory and/or vestibular signs and symptoms that are associated with a bony defect of the superior semicircular canal (SSC). Over the past two decades, advances in diagnostic techniques have raised the awareness of SCDS and treatment approaches have been refined to improve patient outcomes. However, a number of challenges remain. First, there is currently no standardized clinical testing algorithm for quantifying the effects of superior canal dehiscence (SCD). SCDS mimics a number of common otologic disorders and established metrics such as supranormal bone conduction thresholds and vestibular evoked myogenic potential (VEMP) measurements; although useful in certain cases, have diagnostic limitations. Second, while high-resolution computed tomography (CT) is the gold standard for the detection of SCD, a bony defect does not always result in signs and symptoms. Third, even when SCD repair is indicated, there is a lack of consensus about nomenclature to describe the SCD, ideal surgical approach, specific repair techniques, and type of materials used. Finally, there is no established algorithm in evaluation of SCDS patients who fail primary repair and may be candidates for revision surgery. Herein, we will discuss both contemporary and emerging diagnostic approaches for patients with SCDS and highlight challenges and controversies in the management of this unique patient cohort.

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.

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.

Contributions of Contemporary Human Temporal Bone Histopathology to Clinical Otology

Contemporary techniques have greatly enhanced the contributions of human temporal bone (HTB) histopathology to our understanding of the mechanisms of human otologic disease and disease treatment. Herein, we review some of the most salient contributions of this research to disease management. The field of HTB histopathology is challenged by limited resources as applies to trained investigators, infrastructure, and well-equipped laboratories. This research provides insights into clinical otology that cannot be obtained by any other means. Measures should be taken to preserve and extend the contributions of HTB research.

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.

Cavitary Plaques in Otospongiosis: CT Findings and Clinical Implications

BACKGROUND AND PURPOSE

Cavitary plaques have been reported as a manifestation of otospongiosis. They have been related to third window manifestations, complications during cochlear implantation, and sensorineural hearing loss. However, their etiology and clinical implications are not entirely understood. Our purpose was to determine the prevalence, imaging findings, and clinical implications of cavitary plaques in otospongiosis.

MATERIALS AND METHODS

We identified patients with otospongiosis at a tertiary care academic medical center from January 2012 to April 2017. Cross-sectional CT images and clinical records of 47 patients (89 temporal bones) were evaluated for the presence, location, and imaging features of cavitary and noncavitary otospongiotic plaques, as well as clinical symptoms and complications in those who underwent cochlear implantation.

RESULTS

Noncavitary otospongiotic plaques were present in 86 (97%) temporal bones and cavitary plaques in 30 (35%). Cavitary plaques predominated with increasing age (mean age, 59 years; P = .058), mostly involving the anteroinferior wall of the internal auditory canal (P = .003), and their presence was not associated with a higher grade of otospongiosis by imaging (P = .664) or with a specific type of hearing loss (P = .365). No patients with cavitary plaques had third window manifestations, and those with a history of cochlear implantation (n = 6) did not have complications during the procedure.

CONCLUSIONS

Cavitary plaques occurred in one-third of patients with otospongiosis. Typically, they occurred in the anteroinferior wall of the internal auditory canal. There was no correlation with the degree of otospongiosis, type of hearing loss, or surgical complications. Cavitary plaques tended to present in older patients.

Diagnostic performance of high resolution computed tomography in otosclerosis

AIM

To determine the sensitivity and specificity of high resolution computed tomography (HRCT) in the diagnosis of otosclerosis.

METHODS

A systematic literature review was undertaken to include Level I-III studies (Oxford Centre for Evidenced based Medicine) that utilised HRCT to detect histology confirmed otosclerosis. Quantitative synthesis was then performed.

RESULTS

Based on available level III literature, HRCT has a relatively low sensitivity of 58% (95%CI: 49.4-66.9), a high specificity, 95% (95%CI: 89.9-98.0) and a positive predictive value of 92% (95%CI: 84.1-95.8). HRCT is better at diagnosing the more prevalent fenestral form of otosclerosis but remains vulnerable to inframillimetre, retrofenestral and dense sclerotic lesions, despite the advent of more advanced CT scanners with improved collimation.

CONCLUSION

Whilst the diagnosis of otosclerosis remains largely clinical, HRCT remains the gold standard imaging of choice for the middle ear and serves as a useful adjunct to the clinician, helping to delineate extent of disease and exclude other causes.

Lack of Evidence for Nonotosclerotic Stapes Fixation in Human Temporal Bone Histopathology

HYPOTHESIS

Nonotosclerotic stapes fixation does not represent a significant cause of stapes ankylosis in patients undergoing stapedectomy; the vast majority have otosclerosis.

BACKGROUND

Nonotosclerotic stapes fixation has been proposed as the diagnosis in 30 to 40% of patients undergoing stapedectomy (after excluding rare congenital, systemic, and syndromic causes of stapes fixation and tympanosclerosis). This finding was based on the histopathologic evaluation of total stapedectomy surgical specimens. Since these specimens do not include the surrounding otic capsule, the histopathologic evidence of otosclerosis may be missed.

METHODS

Human temporal bone specimens from patients who underwent stapes mobilization, stapedotomy, or stapedectomy during life were evaluated for histologic evidence of otosclerosis. Patients with a history of temporal bone trauma, tympanosclerosis, and congenital, systemic, or syndromic causes of stapes fixation were excluded. Therefore, most temporal bone donors carried a clinical diagnosis of otosclerosis.

RESULTS

Two hundred ten specimens from three temporal bone collections were independently evaluated. Otosclerosis was found on histology in 99% (207/210). Therefore, the incidence of nonotosclerotic stapes fixation was 1% (3/210). In two of the three patients who did not have otosclerosis, the contralateral temporal bone had otosclerosis on histopathologic evaluation. These patients may have had otosclerosis in the footplate only (which was removed at the time of surgery and not available for review).

CONCLUSION

Nonotosclerotic stapes fixation is not likely a distinct pathologic classification from otosclerosis. Most patients diagnosed with nonotosclerotic stapes fixation likely have otosclerosis, but do not have otosclerotic foci in the stapes itself.

Temporal Bone Histopathology in NOG-Symphalangism Spectrum Disorder

OBJECTIVE

To describe the human temporal bone histopathology in NOG-related symphalangism spectrum disorder, a spectrum of congenital stape fixation syndromes caused by mutations in the NOG gene. To discuss implications for clinical management.

PATIENT

A patient with a mutation in the NOG gene.

INTERVENTION(S)

Removal of temporal bones, postmortem temporal bone computed tomography, histologic processing, and review of temporal bones.

MAIN OUTCOME MEASURE(S)

Temporal bone histopathology and correlation with clinical, genetic, audiologic, and radiologic evaluations.

RESULTS

Both temporal bones demonstrated fixation of the stapes footplate to the otic capsule because of a circumferential bridge of calcified cartilage. In the right ear (unoperated), there was no additional abnormality of the ossicles or ossicular joints. In the left ear, fenestrations of the stapes footplate and the lateral semicircular canal were seen, consistent with a history of stapedectomy and fenestration procedure. Severe loss of spiral ganglion neurons throughout the left cochlea accounted for the profound sensorineural hearing loss; there was a normal number of spiral ganglion neurons in the right ear. In both ears, the cochleae demonstrated grossly preserved organs of Corti.

CONCLUSION

The temporal bone pathologic correlate for conductive hearing loss in this patient with a NOG mutation was circumferentially calcified cartilage bridging the stapedovestibular joint space. The temporal bone histopathology findings suggest that conductive hearing loss related to NOG mutation should be improved after stapedectomy; however, care must be taken in extrapolating to all patients with NOG mutations because there may be variability in the pathology, especially given the variability of NOG spectrum disorders.

Imaging of Conductive Hearing Loss With a Normal Tympanic Membrane

OBJECTIVE

This article presents an approach to imaging conductive hearing loss in patients with normal tympanic membranes and discusses entities that should be checked as the radiologist evaluates this potentially complicated issue.

CONCLUSION

Conductive hearing loss in a patient with a normal tympanic membrane is a complicated condition that requires a careful imaging approach. Imaging should focus on otosclerosis, and possible mimics and potential surgical considerations should be evaluated. The radiologist should examine the ossicular chain and the round window and keep in mind that a defect in the superior semicircular canal can disturb the hydraulic integrity of the labyrinth.

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.

Diagnostic yield of MRI for pediatric hearing loss: a systematic review

OBJECTIVE

To perform a systematic review to analyze the diagnostic yield of magnetic resonance imaging (MRI) for pediatric hearing loss, including comparison to computed tomography (CT) and subgroup evaluation according to impairment severity and specific diagnostic findings (cochlear anomalies, enlarged vestibular aqueduct, cochlear nerve abnormalities, and brain findings).

DATA SOURCES

Pubmed, EMBASE, and the Cochrane library were assessed from their inception through December 2013. Manual searches were also performed, and topic experts were contacted.

REVIEW METHODS

Data from studies describing the use of MRI with or without comparison to CT in the diagnostic evaluation of pediatric patients with hearing loss were evaluated, according to a priori inclusion/exclusion criteria. Two independent evaluators corroborated the extracted data. Heterogeneity was evaluated according to the I(2) statistic.

RESULTS

There were 29 studies that evaluated 2434 patients with MRIs and 1451 patients with CTs that met inclusion/exclusion criteria. There was a wide range of diagnostic yield from MRI. Heterogeneity among studies was substantial but improved with subgroup analysis. Meta-analysis of yield differences demonstrated that CT had a greater yield than MRI for enlarged vestibular aqueduct (yield difference 16.7% [95% CI, 9.1%-24.4%]) and a borderline advantage for cochlear anomalies (4.7% [95% CI, 0.1%-9.5%]). Studies were more likely to report brain findings with MRI.

CONCLUSIONS

These data may be utilized in concert with that from studies of risks of MRI and risk/yield of CT to inform the choice of diagnostic testing.

Correlation between histologic and radiographic reconstruction of intracochlear electrode position in human temporal bones

In our laboratory, human temporal bone specimens from patients who in life have undergone cochlear implantation are routinely processed with the implant in situ, embedded in Araldite, sectioned at 20 µm and serially photographed during cutting, stained with toluidine blue and mounted on glass slides. From the images, two-dimensional and three-dimensional reconstructions can be made and a very accurate implant insertion depth can be calculated from the three-dimensional reconstructions. However, this method precludes subsequent special stains and further molecular investigations of the tissue including proteomics and immunostaining, which is now possible with celloidin-embedded tissue. In this study, we correlated measurement of the implant array insertion depth calculated from histologic three-dimensional reconstruction with that measured from three-dimensional radiologic multiplanar reconstruction. Four human temporal bones with cochlear implants underwent postfixation preprocessing CT imaging with a Siemens Somatom Sensation Scanner. The CT scans from these four bones were downloaded into the Voxar software application, reformatted using the multiplanar reconstruction tool, viewed in three dimensions and measurements of intracochlear insertion lengths of the implants were obtained. The bones were processed routinely for in situ Araldite embedding, serial images were made of the block during sectioning, postprocessed using PV-Wave® software, aligned with Amira® software, and used to create histologic three-dimensional reconstructions. From these three-dimensional reconstructions, the insertion depth of the electrode array was mathematically calculated. The range of insertion depths was 15.9 mm (case 1) to 26.6 mm (case 4). The two methods, radiographic multiplanar reconstruction and three-dimensional reconstruction, differed by 0.4-0.9%. This provides confidence that important localization information about the electrode in situ can be gleaned from CT scans, thereby allowing us to extract the implants prior to processing for celloidin embedment and allow further techniques such as special stains and immunostaining to be accomplished in order to evaluate molecular mechanisms involved in cochlear implantation.