Subtle Malformation of the Cochlear Apex and Genetic Abnormalities: Beyond the "Thorny" Cochlea.

With the routine use of high-resolution heavily T2-weighted sequences to evaluate patients with hearing deficits, new, subtle phenotypes of cochlear malformations are being discovered and an increasing number of genotype-phenotype correlations are being found through a reverse phenotype approach, which can help guide geneticists. In this brief report, we present subtle malformations of the apical turn of the cochlea related to 3 genetic mutations, emphasizing the importance of a careful assessment of the cochlear apex.

Retrospective Analysis of the Association of a Small Vestibular Aqueduct with Cochleovestibular Symptoms in a Large, Single-Center Cohort Undergoing CT.

BACKGROUND AND PURPOSE: Temporal bones in some patients with Ménière disease have demonstrated small vestibular aqueducts; however, the prevalence and clinical importance of small vestibular aqueducts remain unclear in patients without Ménière disease. This study correlates the presence of a small vestibular aqueduct with cochleovestibular symptoms. MATERIALS AND METHODS: Consecutive temporal bone CTs in adults from January to December 2020 were reviewed. The midpoint vestibular aqueduct size in the 45°-oblique Pöschl view was measured by 2 reviewers independently in 684 patients (1346 ears). Retrospective chart review for the clinical diagnosis of Ménière disease, the presence of cochleovestibular symptoms, and indications for CT was performed. RESULTS: Fifty-two of 684 patients (7.6% of patients, 62/1346 ears) had small vestibular aqueducts. Twelve patients (15/1346 ears) had Ménière disease. Five of 12 patients with Ménière disease (5 ears) had a small vestibular aqueduct. There was a significant correlation between a small vestibular aqueduct and Ménière disease (P < .001). There was no statistical difference between the small vestibular aqueduct cohort and the cohort with normal vestibular aqueducts (0.3-0.7 mm) regarding tinnitus (P = .06), hearing loss (P = .88), vertigo (P = .26), dizziness (P = .83), and aural fullness (P = .61). CONCLUSIONS: While patients with Ménière disease were proportionately more likely to have a small vestibular aqueduct than patients without Ménière disease, the small vestibular aqueduct was more frequently seen in patients without Ménière disease and had no correlation with hearing loss, vertigo, dizziness, or aural fullness. We suggest that the finding of a small vestibular aqueduct on CT could be reported by radiologists as a possible finding in Ménière disease, but it remains of uncertain, and potentially unlikely, clinical importance in the absence of symptoms of Ménière disease.

The Cochlea in Branchio-Oto-Renal Syndrome: An Objective Method for the Diagnosis of Offset Cochlear Turns.

BACKGROUND AND PURPOSE: An "unwound" or "offset" cochlea has been described as a characteristic imaging feature in patients with branchio-oto-renal syndrome, and recently recognized to be associated in particular to those with EYA1 gene mutations. Determination of this feature has traditionally relied on subjective visual assessment. Our aim was to establish an objective assessment method for cochlear offset (the cochlear turn alignment ratio) and determine an optimal cutoff turn alignment ratio value that separates individuals with EYA1-branchio-oto-renal syndrome from those with SIX1-branchio-oto-renal syndrome and healthy controls. MATERIALS AND METHODS: Temporal bone CT or MR imaging from 40 individuals with branchio-oto-renal syndrome and 40 controls was retrospectively reviewed. Cochlear offset was determined visually by 2 independent blinded readers and then quantitatively via a standardized technique yielding the cochlear turn alignment ratio. The turn alignment ratio values were compared between cochleae qualitatively assessed as "not offset" and "offset." Receiver operating characteristic analysis was used to determine the ability of the turn alignment ratio to differentiate between these populations and an optimal cutoff turn alignment ratio value. Cochlear offset and turn alignment ratio values were analyzed for each branchio-oto-renal syndrome genotype subpopulation and for controls. RESULTS: The turn alignment ratio can accurately differentiate between cochleae with and without an offset (P < .001). The optimal cutoff value separating these populations was 0.476 (sensitivity = 1, specificity = 0.986, J = 0.986). All except 1 cochlea among the EYA1-branchio-oto-renal syndrome subset and all with unknown genotype branchio-oto-renal syndrome had a cochlear offset and a turn alignment ratio of <0.476. All except 1 cochlea among the SIX1-branchio-oto-renal syndrome subset and all controls had no offset and a turn alignment ratio of >0.476. CONCLUSIONS: There is a statistically significant difference in turn alignment ratios between offset and nonoffset cochleae, with an optimal cutoff of 0.476. This cutoff value allows excellent separation of EYA1-branchio-oto-renal syndrome from SIX1-branchio-oto-renal syndrome and from individuals without branchio-oto-renal syndrome or sensorineural hearing loss. The turn alignment ratio is a reliable and objective metric that can aid in the imaging evaluation of branchio-oto-renal syndrome.

Re-Examining the Cochlea in Branchio-Oto-Renal Syndrome: Genotype-Phenotype Correlation.

BACKGROUND AND PURPOSE: Temporal bone imaging plays an important role in the work-up of branchio-oto-renal syndrome. Previous reports have suggested that the unwound or offset cochlea is a highly characteristic marker for branchio-oto-renal syndrome. Our goals were to examine the prevalence of this finding in a branchio-oto-renal syndrome cohort and analyze genetic-phenotypic associations not previously established. MATERIALS AND METHODS: This multicenter retrospective study included 38 ears in 19 unrelated individuals with clinically diagnosed branchio-oto-renal syndrome and confirmed mutations in the EYA1 or SIX1 genes. Two blinded neuroradiologists independently reviewed and documented temporal bone imaging findings in 13 categories for each ear. Imaging phenotypes were correlated with genotypes. RESULTS: There was excellent interrater agreement for all 13 phenotypic categories (κ ≥ 0.80). Of these, 9 categories showed statistically significant differences between patients with EYA1-branchio-oto-renal syndrome and SIX1-branchio-oto-renal syndrome. Cochlear offset was present in 100% of patients with EYA1-branchio-oto-renal syndrome, but in only 1 ear (12.5%) among patients with SIX1-branchio-oto-renal syndrome. A short thorny appearance of the cochlear apical turn was observed in most patients with SIX1-branchio-oto-renal syndrome. CONCLUSIONS: An offset cochlea is associated with the EYA1-branchio-oto-renal syndrome genotype. The SIX1-branchio-oto-renal syndrome genotype is associated with a different cochlear phenotype that almost always is without offset and has a short thorny tip as the apical turn. Therefore, cochlear offset is not a characteristic marker for all patients with branchio-oto-renal syndrome. The lack of a cochlear offset in a patient with clinically suspected branchio-oto-renal syndrome does not exclude the diagnosis and, in fact, may be predictive of the SIX1 genotype.

Retrospective Review of Midpoint Vestibular Aqueduct Size in the 45° Oblique (Pöschl) Plane and Correlation with Hearing Loss in Patients with Enlarged Vestibular Aqueduct.

BACKGROUND AND PURPOSE: Vestibular aqueduct measurements in the 45° oblique (Pöschl) plane provide a reliable depiction of the vestibular aqueduct; however, adoption among clinicians attempting to counsel patients has been limited due to the lack of correlation with audiologic measures. This study aimed to determine the correlation between midpoint vestibular aqueduct measurements in the Pöschl plane in patients with an enlarged vestibular aqueduct with repeat audiologic measures. MATERIALS AND METHODS: Two radiologists independently measured the midpoint vestibular aqueduct diameter in the Pöschl plane reformatted from CT images in 54 pediatric patients (77 ears; mean age at first audiogram, 5 years) with an enlarged vestibular aqueduct. Four hundred nineteen audiograms were reviewed, with a median of 6 audiograms per patient (range, 3-17; mean time between first and last audiograms, 97.4 months). The correlation between midpoint vestibular aqueduct size and repeat audiologic measures (pure tone average, speech-reception threshold, and word recognition score) using a linear mixed-effects model was determined. RESULTS: The mean midpoint vestibular aqueduct size was 1.78 mm (range, 0.81-3.46 mm). There was excellent interobserver reliability with intraclass correlation coefficients for the 2 readers measuring 0.92 (P < .001). Each millimeter increase in vestibular aqueduct size was associated with an increase of 10.5 dB (P = .006) in the pure tone average, an increase of 14.0 dB (P = .002) in the speech-reception threshold, and a decrease in the word recognition score by 10.5% (P = .05). CONCLUSIONS: Midpoint vestibular aqueduct measurements in the Pöschl plane are highly reproducible and demonstrate a significant correlation with audiologic data in this longitudinal study with repeat measures. These data may be helpful for clinicians who are counseling patients with an enlarged vestibular aqueduct using measurements obtained in the Pöschl plane.

Diagnostic Performance of Conebeam CT Pixel Values in Active Fenestral Otosclerosis.

BACKGROUND AND PURPOSE: Quantitative bone densitometry on multidetector CT of the temporal bone is a diagnostic adjunct for otosclerosis in its active (spongiotic) phase, but translating this technique to conebeam CT is limited by the technical variability of conebeam CT pixel values. The purpose of this study was to evaluate the performance of internally calibrated conebeam CT pixel value measurements that can enable the determination of active fenestral otosclerosis (otospongiosis). MATERIALS AND METHODS: This study included 37 ears in 22 patients with a clinical diagnosis of otospongiosis in those ears and 35 ears in 22 control patients without the diagnosis. Temporal bone conebeam CT was performed. ROIs were set anterior to the oval window, in the lateral semicircular canal bone island, and in a nearby aerated space. Mean conebeam CT pixel values in these regions determined the relative attenuation ratio of the area anterior to the oval window normalized to normal otic capsule bone and air. RESULTS: The relative attenuation ratio for cases of otospongiosis was significantly lower than that for controls (P < .001). Based on receiver operating characteristic analysis, the optimal cutoff relative attenuation ratio was 0.876, which had an accuracy of 97.2% for the diagnosis of otospongiosis. CONCLUSIONS: Internally calibrated pixel value ratios in temporal bone conebeam CT can feasibly help diagnose active/spongiotic-phase fenestral otosclerosis in an objective manner.

Radioanatomic Characteristics of the Posteromedial Intraconal Space: Implications for Endoscopic Resection of Orbital Lesions.

BACKGROUND AND PURPOSE: Imaging is essential in the diagnostic work-up of patients with orbital lesions. The position of an orbital lesion relative to the inferomedial muscular trunk of the ophthalmic artery determines endoscopic resectability, anticipated technical difficulty, and patient morbidity. Although the inferomedial muscular trunk is not readily identifiable on preoperative imaging, we hypothesize that it is spatially approximate to the location where the ophthalmic artery crosses the optic nerve. Our aim was to determine whether the ophthalmic artery-optic nerve crosspoint anatomically approximates the inferomedial muscular trunk in a cadaver study and can be appreciated on imaging of known posteromedial orbital lesions. MATERIALS AND METHODS: Dissection was performed on 17 fresh-frozen cadaver orbits to assess the relationship between the inferomedial muscular trunk and ophthalmic artery-optic nerve crosspoint. Retrospective review of imaging in 9 patients with posteromedial orbital lesions assessed posteromedial orbital compartment characteristics and the ability to locate the ophthalmic artery-optic nerve crosspoint. RESULTS: In our cadaver study, the mean distance between the ophthalmic artery-optic nerve crosspoint and the inferomedial muscular trunk was 1.21 ± 0.64 mm. Retrospectively, the ophthalmic artery-optic nerve crosspoint was identifiable in 9/9 patients, whereas the inferomedial muscular trunk was not identifiable in any patient. Total or partial effacement of the posteromedial intraconal fat triangle was observed in 9/9 patients. CONCLUSIONS: This study of neurovascular relationships within the posteromedial orbit demonstrates that the ophthalmic artery-optic nerve crosspoint closely approximates the inferomedial muscular trunk and can be seen in patients with posteromedial orbital lesions. Posteromedial intraconal fat effacement may help to localize these lesions. These findings may facilitate multidisciplinary communication and help predict lesion resectability and patient outcomes.

Comparison of Intraoperative Sonography and Histopathologic Evaluation of Tumor Thickness and Depth of Invasion in Oral Tongue Cancer: A Pilot Study.

BACKGROUND AND PURPOSE: For primary squamous cell carcinoma of the oral tongue, accurate assessment of tumor thickness and depth of invasion is critical for staging and operative management. Currently, typical imaging modalities used for preoperative staging are CT and MR imaging. Intraoperatively, CT or MR imaging cannot provide real-time guidance, and assessment by manual palpation is limited in precision. We investigated whether intraoperative sonography is a feasible technique for assessment of tumor thickness and depth of invasion and validated its accuracy by comparing it with histopathologic evaluation of the resected specimen. MATERIALS AND METHODS: Twenty-six patients with squamous cell carcinoma of the oral tongue who underwent tumor resection by a single surgeon between March 31, 2016, and April 26, 2019, were prospectively identified. Intraoperative sonography was obtained in planes longitudinal and transverse to the long axis of the tumor. Twenty-two patients had archived images that allowed measurements of tumor thickness and depth of invasion sonographically. Two patients had dysplasia and were excluded. The remaining 20 patients had histologic tumor thickness and histologic depth of invasion measured by a single pathologist. RESULTS: The mean sonographic tumor thickness was 7.5 ± 3.5 mm, and the mean histologic tumor thickness was 7.0 ± 4.2 mm. Mean sonographic depth of invasion and histologic depth of invasion were 6.6 ± 3.4 and 6.4 ± 4.4 mm, respectively. There was excellent correlation between sonographic and histologic measurements for both tumor thickness and depth of invasion with Pearson correlation coefficients of 0.95 (95% CI, 0.87-0.98) and 0.95 (95% CI, 0.87-0.98), respectively. CONCLUSIONS: Intraoperative sonography can provide reliable, real-time assessment of the extent of tongue tumors.

Retrospective Review of Otic Capsule Contour and Thickness in Patients with Otosclerosis and Individuals with Normal Hearing on CT.

BACKGROUND AND PURPOSE: Otosclerosis is commonly identified on CT as a focus of hypodensity in the otic capsule anterior to the oval window. However, otosclerosis can have a sclerotic phase approximating the density of normal bone, making diagnosis challenging. This study assesses differences in otic capsule contour and thickness anterolateral to the anterior margin of the oval window in patients with otosclerosis compared with individuals with normal hearing. MATERIALS AND METHODS: Axial CT of 104 ears with clinically diagnosed otosclerosis and 108 consecutive ears of audiometrically normal individuals were retrospectively reviewed. Two radiologists independently evaluated the pattern of otosclerosis, otic capsule contour, and bone thickness on standardized axial images at the level of the oval window and cochleariform process. Measurements were made from the posterolateral margin of the cochlea to the apex of the otic capsule convex contour just anterolateral to the anterior margin of the oval window. In the absence of a convex contour, the sulcus between the oval window and the cochleariform process was identified, and measurement to the depth of the sulcus was used. Receiver operating characteristic analysis determined the best cutoff value of otic capsule thickness. RESULTS: Mean otic capsule thickness (2 SDs) was 3.08 (0.93) mm and 1.82 (0.31) mm in patients with otosclerosis and individuals with normal hearing, respectively (P < .001), with excellent interobserver agreement. Otic capsule thickness of >2.3 mm had 96.2% sensitivity, 100% specificity, 100% positive predictive value, and 96.4% negative predictive value for otosclerosis. A bulging/convex contour of the otic capsule had 68.3% sensitivity, 98.1% specificity, 97.3% positive predictive value, and 76.3% negative predictive value. CONCLUSIONS: Patients with otosclerosis have significantly thicker bone abutting the oval window than individuals with normal hearing.

Measurement for Detection of Incomplete Partition Type II Anomalies on MR Imaging.

BACKGROUND AND PURPOSE: Incomplete partition type II of the cochlea, commonly coexisting with an enlarged vestibular aqueduct, can be a challenging diagnosis on MR imaging due to the presence of a dysplastic spiral lamina-basilar membrane neural complex, which can resemble the normal interscalar septum. The purpose of this study was to determine a reproducible, quantitative cochlear measurement to assess incomplete partition type II anomalies in patients with enlarged vestibular aqueducts using normal-hearing ears as a control population. MATERIALS AND METHODS: Retrospective analysis of 27 patients with enlarged vestibular aqueducts (54 ears) and 28 patients (33 ears) with normal audiographic findings who underwent MR imaging was performed. Using reformatted images from a cisternographic 3D MR imaging produced in a plane parallel to the lateral semicircular canal, we measured the distance (distance X) between the osseous spiral lamina-basilar membrane complex of the upper basal turn and the first linear signal void anterior to the basilar membrane. RESULTS: The means of distance X in patients with normal hearing and prospectively diagnosed incomplete partition type II were, respectively, 0.93 ± 0.075 mm (range, 0.8-1.1 mm) and 1.55 ± 0.25 mm (range, 1-2.1 mm; P < .001). Using 3 SDs above the mean of patients with normal hearing (1.2 mm) as a cutoff for normal, we diagnosed 21/27 patients as having abnormal cochleas; 4/21 were diagnosed retrospectively. This finding indicated that almost 20% of patients were underdiagnosed. Interobserver agreement with 1.2 mm as a cutoff between normal and abnormal produced a κ score of 0.715 (good). CONCLUSIONS: Incomplete partition type II anomalies on MR imaging can be subtle. A reproducible distance X of ≥1.2 mm is considered abnormal and may help to prospectively diagnose incomplete partition type II anomalies.

Vestibular Aqueduct Measurements in the 45° Oblique (Pöschl) Plane.

BACKGROUND AND PURPOSE: The 45° oblique (Pöschl) plane allows reliable depiction of the vestibular aqueduct, with virtually its entire length often visible on 1 CT image. We measured its midpoint width in this plane, aiming to determine normal measurement values based on this plane. MATERIALS AND METHODS: We retrospectively evaluated temporal bone CT studies of 96 pediatric patients without sensorineural hearing loss. Midvestibular aqueduct widths were measured in the 45° oblique plane by 2 independent readers by visual assessment (subjective technique). The vestibular aqueducts in 4 human cadaver specimens were also measured in this plane. In addition, there was a specimen that had undergone CT scanning before sectioning, and measurements made on that CT scan and on the histologic section were compared. Measurements from the 96 patients' CT images were then repeated by using findings derived from the radiologic-histologic comparison (objective technique). RESULTS: All vestibular aqueducts were clearly identifiable on 45° oblique-plane CT images. The mean for subjective measurement was 0.526 ± 0.08 mm (range, 0.337-0.947 mm). The 97.5th percentile value was 0.702 mm. The mean for objective measurement was 0.537 ± 0.077 mm (range, 0.331-0.922 mm). The 97.5th percentile value was 0.717 mm. CONCLUSIONS: Measurements of the vestibular aqueduct can be performed reliably and accurately in the 45° oblique plane. The mean midpoint width was 0.5 mm, with a range of 0.3-0.9 mm. These may be considered normal measurement values for the vestibular aqueduct midpoint width when measured in the 45° oblique plane.

Imaging appearance of the lateral rectus-superior rectus band in 100 consecutive patients without strabismus.

BACKGROUND AND PURPOSE: The lateral rectus-superior rectus band is an orbital connective tissue structure that has been implicated in a form of strabismus termed sagging eye syndrome. Our purpose was to define the normal MR imaging and CT appearance of this band in patients without strabismus. MATERIALS AND METHODS: Orbital MR imaging and CT examinations in 100 consecutive patients without strabismus were evaluated. Readers graded the visibility of the lateral rectus-superior rectus band on coronal T1WI, coronal STIR, and coronal CT images. Readers determined whether the band demonstrated superotemporal bowing or any discontinuities and whether a distinct lateral levator aponeurosis was seen. Reader agreement was assessed by κ coefficients. Association between imaging metrics and patient age/sex was calculated by using the Fisher exact test. RESULTS: The lateral rectus-superior rectus band was visible in 95% of coronal T1WI, 68% of coronal STIR sequences, and 70% of coronal CT scans. Ninety-five percent of these bands were seen as a continuous, arc-like structure extending from the superior rectus/levator palpebrae muscle complex to the lateral rectus muscle; 24% demonstrated superotemporal bowing; and in 82% of orbits, a distinct lateral levator aponeurosis was visible. Increasing patient age was negatively associated with lateral rectus-superior rectus band visibility (P=.03), positively associated with lateral rectus-superior rectus band superotemporal bowing (P=.03), and positively associated with lateral levator aponeurosis visibility (P=.01). CONCLUSIONS: The lateral rectus-superior rectus band is visible in most patients without strabismus on coronal T1WI. The age effect with respect to its visibility and superotemporal bowing could represent age-related connective tissue degeneration.