Incomplete partition type II in its various manifestations: isolated, in association with EVA, syndromic, and beyond; a multicentre international study.

PURPOSE: Incomplete partition type II (IP-II) is characterized by specific histological features and radiological appearance. It may occur in isolation or in association with an enlarged vestibular aqueduct (EVA). Among those with IP-II and EVA, a subset has a diagnosis of Pendred syndrome. This study aimed to explore the prevalence of isolated IP-II, IP-II with EVA, and cases with a genetic or syndromic basis in our cohort. METHODS: From a large, multicentre database of dysplastic cochleae (446 patients, 892 temporal bones), those with imaging features of IP-II were examined in detail, including whether there was a genetic or syndromic association. RESULTS: A total of 78 patients with IP-II were identified. Among these, 55 patients had bilateral IP-II and EVA (only 12 with typical Mondini triad), 8 with bilateral IP-II and normal VA, 2 with bilateral IP-II and unilateral EVA, and 13 with unilateral IP-II (9 with unilateral EVA). Among the group with bilateral IP-II and bilateral EVA in whom genetic analysis was available, 14 out of 29 (48%) had SLC26A4 mutations and a diagnosis of Pendred syndrome, 1 had a FOXI1 mutation, and a few other genetic abnormalities; none had KCNJ10 pathogenic variants. CONCLUSION: Bilateral IP-II-bilateral EVA may be seen in the context of Pendred syndrome (SLC26A4 or FOXI1 mutations) but, in the majority of our cohort, no genetic abnormalities were found, suggesting the possibility of unknown genetic associations. IP-II in isolation (without EVA) is favored to be genetic when bilateral, although the cause is often unknown.

Optic Nerve T2 Signal Intensity and Caliber Reflect Clinical Severity in Genetic Optic Atrophy.

BACKGROUND: Genetic optic atrophies comprise phenotypically heterogenous disorders of mitochondrial function. We aimed to correlate quantitative neuroimaging findings of the optic nerves in these disorders with clinical measures. METHODS: From a retrospective database of 111 patients with bilateral optic atrophy referred for genetic testing, 15 patients diagnosed with nonglaucomatous optic atrophy of genetic origin (7 patients with pathogenic variants in OPA1, 3 patients with Wolfram syndrome, and 5 patients with Leber hereditary optic neuropathy) who had accessible magnetic resonance (MR) images of the orbits and/or brain were analyzed. The primary outcome measures of T2 short Tau inversion recovery (STIR) signal and optic nerve caliber were quantified according to a standardized protocol, normalized to internal standards, and compared between cases and controls. Inter-rater reliability was assessed and clinical features were analyzed according to MRI features. RESULTS: Compared with control patients, the 15 genetic optic atrophy patients demonstrated significantly increased T2 STIR signal (fold-change 1.6, P = 0.0016) and decreased optic nerve caliber (fold-change 0.72, P = 0.00012) after internal normalization. These metrics were reliable (inter-reader reliability correlation coefficients of 0.98 [P = 0.00036] and 0.74 [P = 0.0025] for normalized STIR and nerve caliber, respectively) and significantly correlated with visual acuity, cup-to-disc ratio, and visual field testing. CONCLUSION: Normalized optic nerve STIR signal and optic nerve caliber significantly correlate with visual acuity, cup-to-disc ratio, and perimetric performance in patients with genetic optic atrophy. A formalized protocol to characterize these differences on MRI may help to guide accurate and expedient diagnostic evaluation.

Diagnostic performance of computed tomography features in detecting oropharyngeal squamous cell carcinoma extranodal extension.

OBJECTIVES: Accurate pre-treatment imaging determination of extranodal extension (ENE) could facilitate the selection of appropriate initial therapy for HPV-positive oropharyngeal squamous cell carcinoma (HPV + OPSCC). Small studies have associated 7 CT features with ENE with varied results and agreement. This article seeks to determine the replicable diagnostic performance of these CT features for ENE. METHODS: Five expert academic head/neck neuroradiologists from 5 institutions evaluate a single academic cancer center cohort of 75 consecutive HPV + OPSCC patients. In a web-based virtual laboratory for imaging research and education, the experts performed training on 7 published CT features associated with ENE and then independently identified the "single most (if any) suspicious" lymph node and presence/absence of each of the features. Inter-rater agreement was assessed using percentage agreement, Gwet's AC1, and Fleiss' kappa. Sensitivity, specificity, and positive and negative predictive values were calculated for each CT feature based on histologic ENE. RESULTS: All 5 raters identified the same node in 52 cases (69%). In 15 cases (20%), at least one rater selected a node and at least one rater did not. In 8 cases (11%), all raters selected a node, but at least one rater selected a different node. Percentage agreement and Gwet's AC1 coefficients were > 0.80 for lesion identification, matted/conglomerated nodes, and central necrosis. Fleiss' kappa was always < 0.6. CT sensitivity for histologically confirmed ENE ranged 0.18-0.94, specificity 0.41-0.88, PPV 0.26-0.36, and NPV 0.78-0.96. CONCLUSIONS: Previously described CT features appear to have poor reproducibility among expert head/neck neuroradiologists and poor predictive value for histologic ENE. KEY POINTS: • Previously described CT imaging features appear to have poor reproducibility among expert head and neck subspecialized neuroradiologists as well as poor predictive value for histologic ENE. • Although it may still be appropriate to comment on the presence or absence of these CT features in imaging reports, the evidence indicates that caution is warranted when incorporating these features into clinical decision-making regarding the likelihood of ENE.

Comparison between computed tomography and ultrasound for presurgical evaluation of oral tongue squamous cell carcinoma tumor thickness.

PURPOSE: To compare the accuracy of oral tongue squamous cell carcinoma (OTSCC) tumor thickness (TT) measured on CT to intraoperative ultrasound (US) and histopathology. METHODS AND MATERIALS: Twenty-six patients with OTSCC who underwent tumor resection by a single surgeon with simultaneous intraoperative US between 3/2016 and 4/2019 were prospectively identified, and their data reviewed. TT was independently measured in 19 patients who underwent preoperative CT (cTT) by two neuroradiologists blinded to US and histological results. The confidence level of interpretation of cTT was recorded by each reader using a 5-point Likert scale. The degree of dental artifact on CT was also scored. cTT was compared to TT measured on intraoperative US (uTT) and histopathologic assessment of TT (hTT). RESULTS: OTSCC was visualized on CT in 52% (10/19) and 63% (12/19) of cases for readers 1 and 2, respectively. Mean Likert score was 0.42 for reader 1 and 0.73 for reader 2. Mean cTT of OTSCCs was 5.8 mm +/- 1.7 mm (n = 11). In comparison, mean uTT and hTT were 7.6 mm±3.5 mm and 7.1 +/- 4.2 mm, respectively. The Pearson coefficient (95% confidence interval) was 0.10 (-0.53-0.66) between cTT and hTT (n = 11) and 0.93 (0.74-0.98) between uTT and hTT. CONCLUSIONS: Preoperative CT is not reliable for assessment of TT in OTSCC compared to US and histopathology, particularly for OTSCC under 10 mm. US offers a practical complementary imaging tool with a unique role for primary tumor assessment that can aid in pre-operative planning, especially for small tumors.

Pediatric Tongue Lesions: An Often-Overlooked but Important Collection of Diagnoses.

OBJECTIVE. The purpose of this article is to discuss imaging techniques and provide a pictorial review of pediatric tongue lesions. CONCLUSION. Pediatric tongue lesions represent an often-overlooked collection of abnormalities with a variety of clinical and radiologic features. The location of these lesions places the patient at risk for airway compromise. Systematic imaging evaluation of pediatric tongue lesions can help the radiologist arrive at a correct and timely diagnosis, thus improving and expediting patient care.

Temporal bone computed tomography findings associated with feasibility of endoscopic ear surgery.

PURPOSE: There are no formal radiologic criteria to stratify patients for transcanal (TEES) or transmastoid endoscopic ear surgery for resection of cholesteatoma. We aim to determine 1) whether standard preoperative computed tomography (CT) findings are associated with the need for conversion to a transmastoid approach and 2) the amount of time added for conversion from TEES to transmastoid techniques. MATERIALS AND METHODS: Retrospective chart review of consecutive pediatric and adult cases of TEES for primary cholesteatoma from 2013 through 2015 (n=52). TEES cases were defined as endoscope-only procedures that did not require a transmastoid approach (n=33). Conversion cases were defined as procedures that began as TEES however, required conversion to a transmastoid approach due to the inability to complete cholesteatoma removal (n=19). Preoperative CT findings and total operating room (OR) times of TEES and conversion cases were compared. RESULTS: Preoperative CT scan characteristics that were associated with conversion included tegmen erosion (p=0.026), malleus erosion (p<0.001), incus erosion (p=0.009), mastoid opacification (p=0.009), soft tissue opacification extending into the aditus ad antrum (p=0.009) and into antrum (p=0.006). Total OR time for TEES cases was significantly shorter than conversion cases (median 143min versus 217min, p<0.001). CONCLUSIONS: Preoperative CT findings, notably extension of soft tissue in the aditus ad antrum, antrum and mastoid, are associated with need for conversion to transmastoid technique to achieve removal of cholesteatoma. Endoscope-only cases were significantly faster than cases that required conversion to a transmastoid approach.

Unilateral hypoplasia with contralateral hypertrophy of anterior belly of digastric muscle: a case report.

Anomalies of the anterior belly of the digastric muscle (DM) are uncommon. We present a case of hypoplasia of the anterior belly of the left DM with hypertrophy of the anterior belly of the contralateral DM. The importance of recognizing this finding is to differentiate hypoplasia of the anterior belly of the DM from denervation atrophy, and not to confuse contralateral hypertrophy with a submental mass or lymphadenopathy. In denervation atrophy of the anterior belly of the DM, associated atrophy of the ipsilateral mylohyoid muscle is present. Hypertrophy of the anterior belly of the contralateral DM can be differentiated from a submental mass or lymphadenopathy by recognizing its isodensity on computed tomography and isointensity on magnetic resonance imaging to other muscles, without abnormal contrast enhancement.

Imaging Review of the Temporal Bone: Part II. Traumatic, Postoperative, and Noninflammatory Nonneoplastic Conditions.

The first part of this review of the temporal bone discussed anatomy of the temporal bone as well as inflammatory and neoplastic processes in the temporal bone region (1). This second part will first discuss trauma to the temporal bone and posttraumatic complications. The indications for common surgical procedures performed in the temporal bone and their postoperative imaging appearance are then presented. Finally, a few noninflammatory nonneoplastic entities involving the temporal bone are reviewed. They are relatively uncommon diagnoses compared with infectious or inflammatory diseases. However, because patients present with symptoms that are either common (hearing loss) or distinctive (sensorineural hearing loss in a child), they are important for the radiologist to be aware of and recognize.

Inferior displacement of the lower belly of the lateral pterygoid muscle: a sign of temporomandibular joint lesions.

OBJECTIVE: The purposes of this article are to report the imaging finding of inferior displacement of the lower belly of the lateral pterygoid muscle (LPM) in patients with lesions arising from the temporomandibular joint (TMJ) and to propose that this imaging finding is suggestive of the presence of a TMJ lesion. MATERIALS AND METHODS: We reviewed computed tomographic and magnetic resonance images of 9 patients with lesions involving the TMJ. Images were evaluated for identification of an inferiorly displaced lower belly of the LPM. Pathology reports were reviewed to determine the histopathologic diagnosis of the TMJ lesion. RESULTS: Inferior displacement of the lower belly of the LPM was observed in all cases on magnetic resonance images, computed tomographic images, or both. In 2 cases, the diagnosis was calcium pyrophosphate deposition disease. The remaining cases were ganglion cyst, joint effusion due to dermatomyositis, septic arthritis, chondromyxoid fibroma, synovial chondromatosis, pigmented villonodular synovitis, and giant cell tumor of bone. CONCLUSIONS: Inferior displacement of the lower belly of the LPM is a useful radiologic sign to suggest that a lesion arises from the TMJ.

The ASNR International Collaborations Committee: Cultivating a Global Learning Community.

The American Society of Neuroradiology has expanded its global presence, driven by the efforts of the International Collaborations Committee. This committee is actively involved in training radiologists and fostering collaborations worldwide in the fields of education, research, and community service. This article explores key initiatives of the committee, such as the Anne G. Osborn ASNR International Outreach Professor Program, the International Imaging Series, and Virtual Reading Rooms. Additionally, we provide insight into recent developments related to the pandemic and outline future opportunities.

Fenestration of the facial nerve by the stylomastoid artery.

BACKGROUND: Anatomic landmarks such as the tympanomastoid suture line, posterior belly of the digastric muscle, tragal pointer, and styloid process can assist the parotid surgeon in identifying and preserving the facial nerve. Vascular structures such as the posterior auricular artery and its branch, the stylomastoid artery, lay in close proximity to the facial nerve and have been proposed as landmarks for the identification of the facial nerve. In this case report, we describe an anatomic variation in which the stylomastoid artery has fenestrated the main trunk of the facial nerve, dividing it in two. METHODS: Two patients underwent parotidectomy (one for a pleomorphic adenoma, the second for a parotid cyst) through a standard anterograde approach with identification of the usual facial nerve landmarks. RESULTS: The appearance of the main trunk of the facial nerve was unusual in both patients due to its being fenestrated by the stylomastoid artery. The stylomastoid artery was divided, and the remainder of the facial nerve dissection was performed uneventfully with subsequent resection of the parotid mass in both patients. CONCLUSIONS: In rare instances, the stylomastoid artery can penetrate through the common trunk of the facial nerve. This is an important anatomic variant for the parotid surgeon to be aware of, as it can increase the difficulty of facial nerve dissection.

Retrolabyrinthine Bone Thickness as a Radiologic Marker for the Hypoplastic Endotype in Menière Disease.

BACKGROUND AND PURPOSE: Menière disease (MD) manifests in 2 major endotypes: one with a hypoplastic, underdeveloped endolymphatic sac (MD-hp) and the other with a normally developed sac that degenerates over time (MD-dg). Determining the specific endotype in patients is important for predicting disease progression, tailoring patient counseling, and optimizing treatment strategies. Endotype diagnosis involves measuring an angular trajectory of the vestibular aqueduct (ATVA), with an ATVA ≥140° indicative of MD-hp and an ATVA ≤120° of MD-dg. However, assessing the ATVA can be challenging. This study aimed to explore the link between ATVA and the thickness of the retrolabyrinthine bone as an alternative diagnostic measure that could provide differentiation between MD endotypes using CT and MR imaging. MATERIALS AND METHODS: Retrospective review of CT temporal bone imaging from 32 adult patients with definite MD (60 ears) and 33 age-matched controls without MD or other inner ear symptoms (61 ears) was performed. The ATVA and retrolabyrinthine bone thickness were measured using uniform methodology on standardized axial CT images. Comparative analyses were performed to determine the correlation between ATVA and retrolabyrinthine bone thickness. Additionally, from a separate cohort of 11 patients (22 ears), CT and MR examinations of the temporal bone were retrospectively reviewed for retrolabyrinthine bone thickness measurements, to verify the correlation across the 2 modalities. RESULTS: The average retrolabyrinthine bone thickness was statistically significantly different between MD endotypes, being a mean of 0.8 (SD, 0.3) mm in patients with MD-hp (ATVA ≥140°) and 2.0 (SD, 0.9) mm in patients with MD-dg (ATVA ≤120°), with a consistent pattern of thin retrolabyrinthine bone in MD-hp and variable thickness in MD-dg. Receiver operating characteristic curve analysis within the MD cohort revealed that a retrolabyrinthine bone thickness ≥1.2 mm effectively rules out MD-hp. Excellent interrater reliability was noted for the retrolabyrinthine measurement, and there was near-perfect correlation between CT and MR measurements. CONCLUSIONS: Retrolabyrinthine bone thickness proved to be a useful and straightforward alternative marker for distinguishing MD endotypes, being particularly useful for excluding MD-hp. Including information on retrolabyrinthine bone thickness should be considered a routine part of reporting in the context of MD imaging.

Intraoperative Ultrasound for the Management of Oral Tongue Cancer: a Systematic Review and Meta-Analysis.

Objective: To evaluate for correlation between intraoperative ultrasound (IOUS)-measured tumor thickness (TT) (uTT) and histopathological TT (hTT), and to compare IOUS-assisted resection with conventional resection in patients with oral tongue cancers. Data Sources: Ovid MEDLINE (1946-2023), Embase.com (1947-2023), and Web of Science (All Databases 1900-2023). Review Methods: Inclusion criteria were the use of IOUS for the management of oral tongue cancer. Studies that did not report quantitative data were excluded. Additionally, studies that were not contributory to meta-analysis, or a narrative analysis of pooled results were excluded. Selection was carried out by 2 reviewers. A total of 2417 studies were initially identified, with 12 ultimately being included in this review, and 7 included in the meta-analysis. Data were extracted by 2 investigators and were pooled using a random-effects model. Results: Our meta-analysis reveals a pooled correlation coefficient of 0.92 (95% confidence interval: 0.80-0.96) for studies comparing uTT to hTT. Studies comparing IOUS-assisted resection to conventional resection found IOUS-assisted resection yielded wider nearest margins in all studies reporting this outcome. Conclusion: IOUS reliably measures TT, similarly to that of histopathology measurement. IOUS-assisted resection, which allows the surgeon to view the deep extent of tumor invasion, may increase closest radial margin distance compared to conventional resection. IOUS-assisted resection may represent a more reliable approach to achieving clear margins than conventional resection.

On the Difficulty Predicting Word Recognition Performance After Cochlear Implantation.

HYPOTHESIS: Preimplantation word scores cannot reliably predict postimplantation outcomes. BACKGROUND: To date, there is no model based on preoperative data that can reliably predict the postoperative outcomes of cochlear implantation in the postlingually deafened adult patient. METHODS: In a group of 228 patients who received a cochlear implant between 2002 and 2021, we tested the predictive power of nine variables (age, etiology, sex, laterality of implantation, preimplantation thresholds and word scores, as well as the design, insertion approach, and angular insertion depth of the electrode array) on postimplantation outcomes. Results of multivariable linear regression analyses were then interpreted in light of data obtained from histopathological analyses of human temporal bones. RESULTS: Age and etiology were the only significant predictors of postimplantation outcomes. In agreement with many investigations, preimplantation word scores failed to significantly predict postimplantation outcomes. Analysis of temporal bone histopathology suggests that neuronal survival must fall below 40% before word scores in quiet begin to drop. Scores fall steeply with further neurodegeneration, such that only 20% survival can support acoustically driven word scores of 50%. Because almost all cochlear implant implantees have at least 20% of their spiral ganglion neurons (SGNs) surviving, it is expected that most cochlear implant users on average should improve to at least 50% word recognition score, as we observed, even if their preimplantation score was near zero as a result of widespread hair cell damage and the fact that ~50% of their SGNs have likely lost their peripheral axons. These "disconnected" SGNs would not contribute to acoustic hearing but likely remain electrically excitable. CONCLUSION: The relationship between preimplantation word scores and data describing the survival of SGNs in humans can explain why preimplantation word scores obtained in unaided conditions fail to predict postimplantation outcomes.

Sinonasal (Schneiderian) Tumors in the Temporal Bone: Case Series and Systematic Review.

BACKGROUND: Neoplasms derived from the sinonasal epithelium are a rare finding in the temporal bone, and their origins are controversial. PURPOSE: To review the characteristics of sinonasal epithelial (previously known as Schneiderian) tumors occurring in the temporal bone. DATA SOURCE: This was a 2-center case series and systematic review of MEDLINE, EMBASE, and the Web of Science through May 2021. STUDY SELECTION: Patients with clinicopathologic evidence of temporal bone involvement by neoplasms of sinonasal epithelial origin were selected, with or without a history of prior primary sinonasal epithelial tumors. DATA ANALYSIS: Clinical, radiologic, and pathologic data were extracted. DATA SYNTHESIS: The systematic review included 56 studies and our 8 unpublished cases, totaling 76 cases of papillomas or squamous cell carcinomas in the temporal bone. Of these, 51% occurred secondary to sinonasal tumors, and 49% occurred primarily. Secondary tumors were usually metachronous (77%), with a median delay of 1 year from sinonasal-to-temporal bone tumor diagnosis. Most cases were unilateral (90%); bilateral temporal bone involvement occurred only as secondary ("trilateral") tumors. Unilateral secondary tumors had ipsilateral (81%) or bilateral (19%) sinonasal counterparts. Secondary tumors were more likely to be malignant (OR, 6.7, P < .001). LIMITATIONS: The review was based on case reports and small case series, which are subject to reporting bias. CONCLUSIONS: The observed tumor patterns support the hypothesis that the Eustachian tube facilitates the spread of sinonasal epithelium-derived neoplasms from the sinonasal cavity to the temporal bone. Transtubal spread of sinonasal epithelium-derived neoplasms should be considered among the rare causes of middle ear masses.

Malignant Epithelioid Mesenchymal Neoplasm with FUS::CREM Gene Fusion Arising in the Tongue: A Case Report Detailing Clinicopathological, Imaging, and Molecular Features.

FUS::CREM fusion is a distinct primary driver in rare neoplasms of the head and neck and other anatomic sites. Herein, we describe the clinicopathological, imaging, and molecular features of a malignant epithelioid mesenchymal neoplasm harboring FUS::CREM fusion, arising in the tongue of a 46-year-old male. Clinically, the patient presented with a left upper neck mass. Imaging revealed a 4.0 cm mass at the left base of tongue. Histologically, the tumor consisted of sheets of loosely cohesive, small round to ovoid cells with moderate cytoplasm, small nuclei with coarse chromatin, frequent nuclear pseudoinclusions, and dense peripheral lymphoplasmacytic and histiocytic infiltrates. Malignant features, including tumor necrosis, perineural invasion, and increased mitotic activity were observed; however, lymphovascular invasion was absent with no evidence metastatic disease in the examined lymph nodes. A comprehensive panel of immunohistochemical stains showed positivity for synaptophysin and ALK, with negative results for all other markers. RNA-based next-generation sequencing using anchored multiplex polymerase chain reaction (PCR) was performed and detected FUS::CREM fusion gene. The patient was treated by excision and postsurgical chemoradiation with no evidence of recurrence after four months. Additional cases supported by comprehensive clinical data collected over an extended period are necessary to precisely characterize epithelioid mesenchymal neoplasms harboring FUS::CREM fusion in the head and neck.

An External Validation Study for Automated Segmentation of Vestibular Schwannoma.

OBJECTIVE: To validate how an automated model for vestibular schwannoma (VS) segmentation developed on an external homogeneous dataset performs when applied to internal heterogeneous data. PATIENTS: The external dataset comprised 242 patients with previously untreated, sporadic unilateral VS undergoing Gamma Knife radiosurgery, with homogeneous magnetic resonance imaging (MRI) scans. The internal dataset comprised 10 patients from our institution, with heterogeneous MRI scans. INTERVENTIONS: An automated VS segmentation model was developed on the external dataset. The model was tested on the internal dataset. MAIN OUTCOME MEASURE: Dice score, which measures agreement between ground truth and predicted segmentations. RESULTS: When applied to the internal patient scans, the automated model achieved a mean Dice score of 61% across all 10 images. There were three tumors that were not detected. These tumors were 0.01 ml on average (SD = 0.00 ml). The mean Dice score for the seven tumors that were detected was 87% (SD = 14%). There was one outlier with Dice of 55%-on further review of this scan, it was discovered that hyperintense petrous bone had been included in the tumor segmentation. CONCLUSIONS: We show that an automated segmentation model developed using a restrictive set of siloed institutional data can be successfully adapted for data from different imaging systems and patient populations. This is an important step toward the validation of automated VS segmentation. However, there are significant shortcomings that likely reflect limitations of the data used to train the model. Further validation is needed to make automated segmentation for VS generalizable.

Inner Ear Breaches from Vestibular Schwannoma Surgery: Revisiting the Incidence of Otologic Injury from Retrosigmoid and Middle Cranial Fossa Approaches.

OBJECTIVE: To assess the rate of iatrogenic injury to the inner ear in vestibular schwannoma resections. STUDY DESIGN: Retrospective case review. SETTING: Multiple academic tertiary care hospitals. PATIENTS: Patients who underwent retrosigmoid or middle cranial fossa approaches for vestibular schwannoma resection between 1993 and 2015. INTERVENTION: Diagnostic with therapeutic implications. MAIN OUTCOME MEASURE: Drilling breach of the inner ear as confirmed by operative note or postoperative computed tomography (CT). RESULTS: 21.5% of patients undergoing either retrosigmoid or middle fossa approaches to the internal auditory canal were identified with a breach of the vestibulocochlear system. Because of the lack of postoperative CT imaging in this cohort, this is likely an underestimation of the true incidence of inner ear breaches. Of all postoperative CT scans reviewed, 51.8% had an inner ear breach. As there may be bias in patients undergoing postoperative CT, a middle figure based on sensitivity analyses estimates the incidence of inner ear breaches from lateral skull base surgery to be 34.7%. CONCLUSIONS: A high percentage of vestibular schwannoma surgeries via retrosigmoid and middle cranial fossa approaches result in drilling breaches of the inner ear. This study reinforces the value of preoperative image analysis for determining risk of inner ear breaches during vestibular schwannoma surgery and the importance of acquiring CT studies postoperatively to evaluate the integrity of the inner ear.

Imaging review of the temporal bone: part I. Anatomy and inflammatory and neoplastic processes.

From a clinical-radiologic standpoint, there are a limited number of structures and disease entities in the temporal bone with which one must be familiar in order to proficiently interpret a computed tomographic or magnetic resonance imaging study of the temporal bone. It is helpful to examine the region in an organized and systematic fashion, going through the same checklist of key structures each time. This is the first of a two-part review that provides a practical approach to understanding temporal bone anatomy, localizing a pathologic process with a focus on inflammatory and neoplastic processes, identifying pertinent positives and negatives, and formulating a differential diagnosis.