Cross Sectional Imaging of the Ear and Temporal Bone

Deep Learning for Automated Image Segmentation of the Middle Ear: A Scoping Review

OBJECTIVE

Convolutional neural networks (CNNs) have revolutionized medical image segmentation in recent years. This scoping review aimed to carry out a comprehensive review of the literature describing automated image segmentation of the middle ear using CNNs from computed tomography (CT) scans.

DATA SOURCES

A comprehensive literature search, generated jointly with a medical librarian, was performed on Medline, Embase, Scopus, Web of Science, and Cochrane, using Medical Subject Heading terms and keywords. Databases were searched from inception to July 2023. Reference lists of included papers were also screened.

REVIEW METHODS

Ten studies were included for analysis, which contained a total of 866 scans which were used in model training/testing. Thirteen different architectures were described to perform automated segmentation. The best Dice similarity coefficient (DSC) for the entire ossicular chain was 0.87 using ResNet. The highest DSC for any structure was the incus using 3D-V-Net at 0.93. The most difficult structure to segment was the stapes, with the highest DSC of 0.84 using 3D-V-Net.

CONCLUSIONS

Numerous architectures have demonstrated good performance in segmenting the middle ear using CNNs. To overcome some of the difficulties in segmenting the stapes, we recommend the development of an architecture trained on cone beam CTs to provide improved spatial resolution to assist with delineating the smallest ossicle.

IMPLICATIONS FOR PRACTICE

This has clinical applications for preoperative planning, diagnosis, and simulation.

Ultra-high-resolution CT of the temporal bone: Comparison between deep learning reconstruction and hybrid and model-based iterative reconstruction

PURPOSE

The purpose of this study was to evaluate the ability of ultra-high-resolution computed tomography (UHR-CT) to assess stapes and chorda tympani nerve anatomy using a deep learning (DLR), a model-based, and a hybrid iterative reconstruction algorithm compared to simulated conventional CT.

MATERIALS AND METHODS

CT acquisitions were performed with a Mercury 4.0 phantom. Images were acquired with a 1024 × 1024 matrix and a 0.25 mm slice thickness and reconstructed using DLR, model-based, and hybrid iterative reconstruction algorithms. To simulate conventional CT, images were also reconstructed with a 512 × 512 matrix and a 0.5 mm slice thickness. Spatial resolution, noise power spectrum, and objective high-contrast detectability were compared. Three radiologists evaluated the clinical acceptability of these algorithms by assessing the thickness and image quality of the stapes footplate and superstructure elements, as well as the image quality of the chorda tympani nerve bony and tympanic segments using a 5-point confidence scale on 13 temporal bone CT examinations reconstructed with the four algorithms.

RESULTS

UHR-CT provided higher spatial resolution than simulated conventional CT at the penalty of higher noise. DLR and model-based iterative reconstruction provided better noise reduction than hybrid iterative reconstruction, and DLR had the highest detectability index, regardless of the dose level. All stapedial structure thicknesses were thinner using UHR-CT by comparison with conventional simulated CT (P < 0.009). DLR showed the best visualization scores compared to the other reconstruction algorithms (P < 0.032).

CONCLUSION

UHR-CT with DLR results in less noise than UHR-CT with hybrid iterative reconstruction and significantly improves stapes and tympanic chorda tympani nerve depiction compared to simulated conventional CT and UHR-CT with iterative reconstruction.

Outcomes of Spontaneous Cerebrospinal Fluid Leak Repair With Concurrent Eustachian Tube Dysfunction

OBJECTIVE

To compare the presentation and outcomes of patients with and without obstructive eustachian tube dysfunction (oETD) undergoing repair of lateral skull base spontaneous cerebrospinal fluid (sCSF) leaks.

STUDY DESIGN

Retrospective chart review.

SETTING

Tertiary referral center.

PATIENTS

Adults with lateral skull base sCSF leaks who underwent repairs from January 1, 2011, to December 31, 2020, were collected.

MAIN OUTCOME MEASURE

Comparative statistics and effect sizes were used to compare clinical features, operative findings, and outcomes between groups.

RESULTS

Of 92 ears from 89 patients included, 51.1% (n = 47) had oETD. There were no differences in demographics between patients with and without oETD. Mean age was 60.7 ± 13.1 versus 58.5 ± 12.8 years ( d = -0.17 [-0.58 to 0.24]), mean body mass index was 33.8 ± 8.5 versus 36.0 ± 8.0 kg/m 2 ( d = 0.27 [-0.14 to 0.68]), and female sex preponderance was 59.6% (n = 28) versus 68.8% (n = 31; Φ = -0.09), respectively. There were no differences in the radiologic number, size, and locations of defects. Patients with oETD had less pneumatized mastoids than those without oETD ( p = 0.001; Φ = 0.43). Mean change from preoperative to postoperative air pure-tone average for those with and without oETD was -1.1 ± 12.6 versus 0.1 ± 17.2 dB ( d = 0.09 [-0.04 to 0.58]), respectively. Six ears (6.5%; three with and three without oETD) underwent revisions for rhinorrhea/otorrhea between 5 and 28 months postoperatively, during which four leaks were found, the two patients without leaks had oETD.

CONCLUSIONS

The presentation of sCSF leaks and outcomes of repairs in patients with oETD do not differ from those without oETD. Although postoperative otorrhea might represent an inflammatory or infectious process in patients with oETD, reexploration is warranted if patients do not improve with conservative treatment.

Anatomy of the rabbit inner ear using computed tomography and magnetic resonance imaging

Anatomically, the inner ear is a highly complex organ of intricate design, composed of a bony labyrinth that encases the same-shaped membranous labyrinth. It is difficult to study the three-dimensional anatomy of the inner ear because the relevant structures are very small and embedded within the petrous temporal bone, one of the densest bones in the body. The current study aimed to provide a detailed anatomic reference for the normal anatomy of the rabbit's inner ear. As a study model, ten healthy adults New Zealand White rabbit heads were used. Six heads were used for macroscopic evaluation of the bony and membranous labyrinths. The remaining four heads were evaluated radiographically, where 3D images were generated of the bony and membranous labyrinths using data sets from computed tomography (CT) and magnetic resonance imaging (MRI), respectively. The anatomical structures were identified and labelled according to NominaAnatomicaVeterinaria (NAV). Our study revealed that CT and MRI are the optimal cross-sectional imaging modalities for investigating such tiny and often inaccessible inner ear structures. As high-quality scanners are not readily available to veterinarians, the CT and MRI images generated by this research were of lower quality; therefore, high-quality dissections were used to identify/support structures seen in these images. In conclusion, this study provides one of the first investigations that uses multislice CT scans and MRI to study the rabbit's inner ear and its correlation with the corresponding anatomical images. Both anatomical, CT and MRI images will serve as a reference for interpreting pathologies relative to the rabbit's inner ear.

Automated Extraction of Anatomical Measurements From Temporal Bone CT Imaging

OBJECTIVE

Proposed methods of minimally invasive and robot-assisted procedures within the temporal bone require measurements of surgically relevant distances and angles, which often require time-consuming manual segmentation of preoperative imaging. This study aims to describe an automatic segmentation and measurement extraction pipeline of temporal bone cone-beam computed tomography (CT) scans.

STUDY DESIGN

Descriptive study of temporal bone measurements.

SETTING

Academic institution.

METHODS

A propagation template composed of 16 temporal bone CT scans was formed with relevant anatomical structures and landmarks manually segmented. Next, 52 temporal bone CT scans were autonomously segmented using deformable registration techniques from the Advanced Normalization Tools Python package. Anatomical measurements were extracted via in-house Python algorithms. Extracted measurements were compared to ground truth values from manual segmentations.

RESULTS

Paired t test analyses showed no statistical difference between measurements using this pipeline and ground truth measurements from manually segmented images. Mean (SD) malleus manubrium length was 4.39 (0.34) mm. Mean (SD) incus short and long processes were 2.91 (0.18) mm and 3.53 (0.38) mm, respectively. The mean (SD) maximal diameter of the incus long process was 0.74 (0.17) mm. The first and second facial nerve genus had mean (SD) angles of 68.6 (6.7) degrees and 111.1 (5.3) degrees, respectively. The facial recess had a mean (SD) span of 3.21 (0.46) mm. Mean (SD) minimum distance between the external auditory canal and tegmen was 3.79 (1.05) mm.

CONCLUSIONS

This is the first study to automatically extract relevant temporal bone anatomical measurements from CT scans using segmentation propagation. Measurements from these models can streamline preoperative planning, improve future segmentation techniques, and help develop future image-guided or robot-assisted systems for temporal bone procedures.

Trans-cortical vessels in the mouse temporal bulla bone are a means to recruit myeloid cells in chronic otitis media and limit peripheral leukogram changes

Chronic otitis media, inflammation of the middle ear, is a sequel to acute otitis media in ∼8% of children. Chronic otitis media with effusion is the most common cause of childhood deafness and is characterised by effusion of white blood cells into the auditory bulla cavity. Skull flat bones have trans-cortical vessels which are responsible for the majority of blood flow in and out of the bone. In experimental models of stroke and aseptic meningitis there is preferential recruitment of myeloid cells (neutrophils and monocytes) from the marrow in skull flat bones. We report trans-cortical vessels in the mouse temporal bone connect to the bulla mucosal vasculature and potentially represent a means to recruit myeloid cells directly into the inflamed bulla. The mutant mouse strains Junbo (Mecom^Jbo/+) and Jeff (Fbxo11^Jf/+) develop chronic otitis spontaneously; Mecom^Jbo/+ mice have highly cellular neutrophil (90%) rich bulla exudates whereas Fbxo11^Jf/+ mice have low cellularity serous effusions (5% neutrophils) indicating differing demand for neutrophil recruitment. However we found peripheral leukograms of Mecom^Jbo/+ and Fbxo11^Jf/+ mice are similar to their respective wild-type littermate controls with healthy bullae and infer preferential mobilization of myeloid cells from temporal bulla bone marrow may mitigate the need for a systemic inflammatory reaction. The cytokines, chemokines and haematopoietic factors found in the inflamed bulla represent candidate signalling molecules for myeloid cell mobilization from temporal bone marrow. The density of white blood cells in the bulla cavity is positively correlated with extent of mucosal thickening in Mecom^Jbo/+, Fbxo11^Jf/+, and Eda^Ta mice and is accompanied by changes in epithelial populations and bone remodelling. In Mecom^Jbo/+ mice there was a positive correlation between bulla cavity WBC numbers and total bacterial load. The degree of inflammation varies between contralateral bullae and between mutant mice of different ages suggesting inflammation may wax and wane and may be re-initiated by a new wave of bacterial infection. Clearance of white blood cells and inflammatory stimuli from the bulla cavity is impaired and this may create a pro-inflammatory feedback loop which further exacerbates otitis media and delays its resolution.

A New Frontier in Temporal Bone Imaging: Photon-Counting Detector CT Demonstrates Superior Visualization of Critical Anatomic Structures at Reduced Radiation Dose

BACKGROUND AND PURPOSE

Photon-counting detector CT is a new technology with a limiting spatial resolution of ≤150 μm. In vivo comparisons between photon-counting detector CT and conventional energy-integrating detector CT are needed to determine the clinical impact of photon counting-detector CT in temporal bone imaging.

MATERIALS AND METHODS

Prospectively recruited patients underwent temporal bone CT examinations on an investigational photon-counting detector CT system after clinically indicated temporal bone energy-integrating detector CT. Photon-counting detector CT images were obtained at an average 31% lower dose compared with those obtained on the energy-integrating detector CT scanner. Reconstructed images were evaluated in axial, coronal, and Pöschl planes using the smallest available section thickness on each system (0.4 mm on energy-integrating detector CT; 0.2 mm on photon-counting detector CT). Two blinded neuroradiologists compared images side-by-side and scored them using a 5-point Likert scale. A post hoc reassignment of readers' scores was performed so that the scores reflected photon-counting detector CT performance relative to energy-integrating detector CT.

RESULTS

Thirteen patients were enrolled, resulting in 26 image sets (left and right sides). The average patient age was 63.6 [SD, 13.4] years; 7 were women. Images from the photon-counting detector CT scanner were significantly preferred by the readers in all reconstructed planes (P < .001). Photon-counting detector CT was rated superior for the evaluation of all individual anatomic structures, with the oval window (4.79) and incudostapedial joint (4.75) receiving the highest scores on a Likert scale of 1-5.

CONCLUSIONS

Temporal bone CT images obtained on a photon-counting detector CT scanner were rated as having superior spatial resolution and better critical structure visualization than those obtained on a conventional energy-integrating detector scanner, even with a substantial dose reduction.

Does Vestibulo-Ocular Reflex (VOR) Gain Correlate With Radiological Findings in the Semi-Circular Canals in Patients Carrying the p.Pro51Ser (P51S) COCH Variant Causing DFNA9? Relationship Between the Three-Dimensional Video Head Impulse Test (vHIT) and MR/CT Imaging

OBJECTIVE

The primary aim was to determine whether 3D video-head-impulse-test vestibulo-ocular reflex (vHIT VOR)-gains correlate with computed tomography (CT) and magnetic resonance (MR) lesions in a series of carriers of the p.(Pro51Ser)-variant (P51S) in the COCH-gene (DFNA9). Secondary aim was to compare routine imaging with second peer review radiologic lecture.

STUDY DESIGN

Analytical cross-sectional study.

SETTING

Secondary referral center.

PATIENTS

Twenty-four p.P51S carriers with MR and CT images. Eighteen carriers were selected of whom both 3D-vHIT and imaging data were available within a time interval of 24 months.

INTERVENTIONS

All imaging data were reassessed by two independent neuroradiologists. vHIT VOR-gains were correlated with semi-circular canal (SCC) lesions.

MAIN OUTCOME MEASURES

Correlation between vHIT VOR-gains and SCC lesions, and additional lesions detected during scientific lecture of imaging data.

RESULTS

The average gain of the ipsilateral labyrinth was significantly lower when positive CT (0.3215; p = 0.0122) and MR results (0.3215; p = 0.0134).92% of ears presented MR lesions on at least one SCC, whereas this was 75% on CT. The posterior SCC is the most frequently affected on MR and CT. Second lecture led to nine additional MR and 16 CT lesions.

CONCLUSIONS

Significant correlation was observed between radiological lesions at any SCC and lower average gain of the three ipsilateral SCC. The substantially larger number of lesions during scientific assessment stresses the need to fully inform radiologists concerning differential diagnosis to facilitate accurate diagnosis when planning imaging. Focal sclerosis and narrowing of SCC in DFNA9 represent a possible biomarker of advanced stages of otovestibular deterioration.

Checklist for the evaluation of magnetic resonance imaging in otological pathology

Otolaryngology specialists must be familiar with radiological studies that allow the diagnosis of different otological pathologies. Magnetic resonance imaging is a complement to computed tomography, which allows a better evaluation of soft tissues and contributes to the differential diagnosis of space-occupying lesions located in the temporal bone and lateral skull base. It is also the technique of choice for the evaluation of the inner ear and the anatomical structures located in the cerebellopontine angle. In this article we present a checklist for magnetic resonance imaging of the ear with different sections that will allow a systematic review of all structures of interest in otological practice, as well as the preferred sequences for each situation.

MRI and MR angiography evaluation of pulsatile tinnitus: A focused, physiology-based protocol

BACKGROUND AND PURPOSE

Pulsatile tinnitus (PT) is the subjective sensation of a pulse-synchronous sound, most often due to a cerebrovascular etiology. PT can severely impact quality of life and may indicate a life-threatening process, yet a timely and accurate diagnosis can often lead to effective treatment. Clinical assessment with a history and physical examination can often suggest a diagnosis for PT, but is rarely definitive. Therefore, PT should be evaluated with a comprehensive and targeted radiographic imaging protocol. MR imaging provides a safe and effective means to evaluate PT. Specific MR sequences may be used to highlight different elements of cerebrovascular anatomy and physiology. However, routine MR evaluation of PT must comply with economic and practical constraints, while effectively capturing both common and rarer, life-threatening etiologies of PT.

METHODS

In this state-of-the-art review, we describe our institutional MR protocol for evaluating PT.

RESULTS

This protocol includes the following dedicated sequences: time-of-flight magnetic resonance angiography; arterial spin labeling; spoiled gradient recalled acquisition in the steady state; time-resolved imaging of contrast kinetics; diffusion weighted imaging, and 3-dimensional fluid-attenuated inversion recovery.

CONCLUSIONS

We describe the physiologic and clinical rationale for including each MR sequence in a comprehensive PT imaging protocol, and detail the role of MR within the broader evaluation of PT, from clinical presentation to treatment.

Imaging the External Ear: Practical Approach to Normal and Pathologic Conditions

The external ear (EE) is an osseous-cartilaginous structure that extends from the auricle to the tympanic membrane. It is divided into two parts: the auricle (or pinna) and the external auditory canal (EAC). Given the ease of access to the EE, imaging studies are not always needed to make a diagnosis. However, when lesions block visual access to areas deep to the EE abnormality, complications are suspected, or there is lack of response to treatment, imaging becomes essential. A basic understanding of the embryologic development and knowledge of the anatomy of the auricle and EAC are useful for accurate diagnosis of EE lesions. Congenital, traumatic, inflammatory, neoplastic, and vascular conditions can affect the EE. An overview of the anatomy and embryologic development of the EE is presented, with discussion and illustrations of common and uncommon conditions that affect EE structures and a focus on the CT and MRI features that are of interest to radiologists. CT is usually the first diagnostic modality used to evaluate the EAC and is the superior method for demonstrating bone changes. MRI provides excellent tissue characterization and enables one to better define lesion extension and perineural tumor spread. In addition, a flowchart to facilitate the differential diagnosis of EE abnormalities is provided. Online supplemental material is available for this article. ^©RSNA, 2022.

Checklist for the evaluation of magnetic resonance imaging in otological pathology

Otolaryngology specialists must be familiar with radiological studies that allow the diagnosis of different otological pathologies. Magnetic resonance imaging is a complement to computed tomography, which allows a better evaluation of soft tissues and contributes to the differential diagnosis of space-occupying lesions located in the temporal bone and lateral skull base. It is also the technique of choice for the evaluation of the inner ear and the anatomical structures located in the cerebellopontine angle. In this article we present a checklist for magnetic resonance imaging of the ear with different sections that will allow a systematic review of all structures of interest in otological practice, as well as the preferred sequences for each situation.

New Navigation Approaches for Endoscopic Lateral Skull Base Surgery

Image-guided navigation is well established for surgery of the brain and anterior skull base. Although navigation workstations have been used widely by neurosurgeons and rhinologists for decades, utilization in the lateral skull base (LSB) has been less due to stricter requirements for overall accuracy less than 1 mm in this region. Endoscopic approaches to the LSB facilitate minimally invasive surgeries with less morbidity, yet there are risks of injury to critical structures. With improvements in technology over the years, image-guided navigation for endoscopic LSB surgery can reduce operative time, optimize exposure for surgical corridors, and increase safety in difficult cases.

Imaging findings in patients after the bomb explosion in Somalia on December 28, 2019

INTRODUCTION

This study aimed to present the radiological findings of injuries in victims as a result of a suicide bombing in Mogadishu, Somalia.

METHODS

Of the 82 injured cases admitted to the emergency department within the first six hours after the explosion, those who were radiologically evaluated were included in this retrospective and descriptive study. To analyze and identify the distribution of primary, secondary, and tertiary injuries, they were classified according to the body areas as head-neck, thorax, abdominopelvic, extremity, and vertebra.

RESULTS

The mean age (mean ± SD) of 63 patients included in the study was 28.6 ± 10.2 years. Twenty-four (38.1%) of the injured patients were female and 39 (61.9%) were male. Secondary blast injury was the most common type of injury in the study group with a rate of 39/63 (62%). The total number of bomb fragments was 235, of which 113 (47.8%) were seen in the head and neck region, followed by 86 (36.5%) in the extremities. There were 10 patients (15.9%) with lung injury and 13 (20.6%) with tympanic membrane perforation due to the primary blast mechanism.

CONCLUSION

Radiological imaging plays an important role in identifying specific findings and patterns of explosive injuries. Therefore, we consider that patients with stable hemodynamics should be radiologically examined for a fast and accurate diagnosis or treatment.

Radiological findings in spontaneous cerebrospinal fluid leaks of the temporal bone

BACKGROUND AND OBJECTIVE

Spontaneous cerebrospinal fluid leak of the temporal bone is an emerging clinical entity for which prompt and accurate diagnosis is difficult given the subtle signs and symptoms that patients present with. This study sought to describe the key temporal bone abnormalities in patients with spontaneous cerebrospinal fluid leak.

METHODS

A retrospective cohort study was conducted of adult patients with biochemically confirmed spontaneous cerebrospinal fluid leak. Demographics and radiological features identified on computed tomography imaging of the temporal bones and/or magnetic resonance imaging were analysed.

RESULTS

Sixty-one patients with spontaneous cerebrospinal fluid leak were identified. Fifty-four patients (88.5 per cent) underwent both temporal bone computed tomography and magnetic resonance imaging. Despite imaging revealing bilateral defects in over 75 per cent of the cohort, only two patients presented with bilateral spontaneous cerebrospinal fluid leaks. Anterior tegmen mastoideum defects were most common, with an average size of 2.5 mm (range, 1-10 mm).

CONCLUSION

Temporal bone computed tomography is sensitive for the identification of defects when suspicion exists. In the setting of an opacified middle ear and/or mastoid, close examination of the skull base is crucial given that this fluid is potentially cerebrospinal fluid.

Postoperative Imaging of the Temporal Bone

The anatomy of the temporal bone is complex, and postoperative imaging evaluation of this bone can be challenging. Surgical approaches to the temporal bone can be categorized didactically into tympanoplasty and ossicular reconstruction, mastoidectomy, and approaches to the cerebellopontine angle and internal auditory canal (IAC). In clinical practice, different approaches can be combined for greater surgical exposure. Postoperative imaging may be required for follow-up of neoplastic lesions and to evaluate unexpected outcomes or complications of surgery. CT is the preferred modality for assessing the continuity of the reconstructed conductive mechanism, from the tympanic membrane to the oval window, with use of grafts or prostheses. It is also used to evaluate aeration of the tympanic and mastoid surgical cavities, as well as the integrity of the labyrinth, ossicular chain, and tegmen. MRI is excellent for evaluation of soft tissue. Use of a contrast-enhanced fat-suppressed MRI sequence is optimal for follow-up after IAC procedures. Non-echo-planar diffusion-weighted imaging is optimal for detection of residual or recurrent cholesteatoma. The expected imaging findings and complications of the most commonly performed surgeries involving the temporal bone are summarized in this review. Online supplemental material is available for this article. ^©RSNA, 2021.

Distribution of different morphological types of anterior epitympanic plate “cog” and Köerner’s septum in CT images of cholesteatomatous and non-cholesteatomatous CSOM: is it really significant?

Background

The anterior epitympanic plate (cog) and Köerner’s septum are gaining more importance since the introduction of transcanal mastoidectomy as these anatomical structures are serving landmarks for the attic. Moreover, different morphological types of cog and Köerner’s septum revealed embryological relation to the development of the isthmic membrane; the latter is linked to aeration of the attic and thus affects the pathological development of the cholesteatoma.

Results

A retrospective review of CT images of 86 patients proved by surgical biopsies revealed: 49 cholesteatomas and 37 non-cholesteatomatous CSOM. The type-I “cog” had a higher incidence (n = 40) and was statistically more prevalent in non-cholesteatomatous CSOM (n = 30, 81.1%). Type-II was the second commonest and was statistically more prevalent in cholesteatomatous CSOM (n = 22, 44.9%). Type-III was the third commonest, seen in (n = 18, 20.9%) and was statistically more prevalent in cholesteatomatous CSOM (n = 17, 34.7%). Köerner’s septum was more prevalent in non-cholesteatomatous CSOM (70.3%) with statistical significance (p value = 0.002).

Conclusions

The difference in the distribution of different morphological types of anterior epitympanic plate “cog,” as well as the difference in Köerner’s septum existence amongst cholesteatomatous and non-cholesteatomatous CSOM are suggested as risk factors for the development of cholesteatoma and may predict a cholesteatoma on CT images.

Cross-Sectional Imaging Evaluation of Congenital Temporal Bone Anomalies: What Each Radiologist Should Know

Hearing loss in pediatric age group is associated with many congenital temporal bone disorders. Aberrant development of various ear structures leads into either conductive or sensorineural hearing loss. Knowledge of the embryology and anatomical details of various compartments of the ear help better understanding of such disorders. In general, abnormalities of external and middle ears result in conductive hearing loss. Whereas abnormalities of inner ear structures lead into sensorineural hearing loss. These abnormalities could occur as isolated or part of syndromes. Temporal bone disorders are a significant cause of morbidity and developmental delays in children. Imaging evaluation of children presented with hearing loss is paramount in early diagnosis and proper management planning. Our aim is to briefly discuss embryology and anatomy of the pediatric petrous temporal bones. The characteristic imaging features of commonly encountered congenital temporal bone disorders and their associated syndromes will be discussed.

Metastatic Disease of the Temporal Bone: A Contemporary Review

OBJECTIVES

To identify the frequency and primary site of metastatic pathologies to the temporal bone and characterize the associated symptomatology.

METHODS

The MEDLINE, Embase, and Web of Science databases were systematically reviewed according to the PRISMA guidelines to identify all cases of pathologically confirmed distant temporal bone metastases published with English translation until October 2019. Descriptive statistics were performed.

RESULTS

Out of 576 full-length articles included for review, 109 met final criteria for data extraction providing 255 individual cases of distant temporal bone metastases. There was a male predominance (54.9%) with median age of 59.0 years (range 2-90). The most common locations of primary malignancy included the breasts (19.6%), lungs (16.1%), and prostate (8.6%). Most tumors were carcinomas of epithelial origin (75.3%) and predominantly adenocarcinoma (49.4%). The commonest metastatic sites encountered within the temporal bone were the petrous (72.0%) and mastoid (49.0%) portions. Bilateral temporal bone metastases occurred in 39.8% of patients. Patients were asymptomatic in 32.0% of cases. Symptomatic patients primarily reported hearing loss (44.3%), facial palsy (31.2%), and otalgia (16.6%) for a median duration of 1 month. Petrous lesions were associated with asymptomatic cases (P = .001) while mastoid lesions more often exhibited facial palsy (P = .026), otalgia (P < .001), and otorrhea (P < .001). Non-carcinomatous tumors were associated with petrosal metastasis (P = .025) and asymptomatic cases (P = .109). Carcinomatous metastases more often presented with otalgia (P = .003).

CONCLUSIONS

Temporal bone metastasis is uncommon but should be considered in patients with subacute otologic symptoms or facial palsy and history of distant malignancy. Laryngoscope, 131:1101-1109, 2021.