Lane, John I.

Objective: The differential of an external auditory canal mass is broad. One rare potential cause is a pneumatocele of the tympanic membrane, which has only been described 1 other time in the literature. This report serves to describe the second case of this pathology, including its unique presentation, and benign clinical course. Methods: Case report. Results: A case is discussed in which a pneumatocele of the tympanic membrane was incidentally identified during evaluation of contralateral otologic pathology. The etiology was suspected to be habitual auto-insufflation. After cessation of this practice, the pneumatocele was noted to resolve without further intervention. Conclusion: A tympanic membrane pneumatocele represents a rare cause of an external auditory canal mass. The diagnosis can be made clinically via history, palpation, and otoscopy during auto-insufflation, potentially avoiding further diagnostic testing. Depending on the etiology, resolution can occur after lifestyle modification; however, further interventions may definitively treat the condition if so required.

BackgroundFusion of diffusion‐weighted imaging (DWI) to computed tomography (CT) has been touted as a possible technique to improve cholesteatomas localization. This study set out to assess the ability of DWI images fused with thin‐slice heavily T2‐weighted images to similarly localize surgically‐confirmed cholesteatomas.Materials and MethodsA retrospective review was completed of consecutive patients that underwent MR temporal bone imaging (9/2011–3/2020) with both DWI and thin‐slice T2‐weighted imaging. Included patients underwent surgical resection of primary or recidivistic cholesteatoma after preoperative MR imaging. A neuroradiologist, who was blinded to operative and clinical notes, localized each lesion on both DWI and fused DWI‐T2 images in 11 anatomic subdivisions of the temporal bone. Surgical confirmation of cholesteatoma location was used as the gold standard for comparison.ResultsOf 24 included examinations, the average age at time of MR was 48.2 ± 24.7 years; 12/24 (50.0%) were female. Five of 24 had primary cholesteatoma, while the remainder had recidivistic disease. Sensitivity, specificity, and accuracy of unfused DWI images were 52.1%, 88.9%, and 75.8%, respectively. Sensitivity, specificity, and accuracy of fused DWI‐T2 images were 57.1%, 94.8%, and 81.8%, respectively.ConclusionFused DWI‐T2 images outperformed unfused DWI images in the anatomic localization of temporal bone cholesteatomas. This method represents a potential alternative to MR‐CT fusion for pre‐operative cholesteatoma evaluation, and warrants future investigations. Opposed to MR‐CT fusion, this method only necessitates MR sequences and removes the need for additional CT acquisition.Level of Evidence3 Laryngoscope, 131:E1662–E1667, 2021

Objective: To evaluate adverse events and feasibility of performing 1.5-T MRI in patients with cochlear implants (CI) and auditory brainstem implants (ABI). Setting: Single tertiary academic referral center. Patients: CI and ABI recipients undergoing 1.5-T MRI without internal magnet removal. Intervention(s): MRI after tight headwrap application. Main Outcome Measures: Adverse events, patient tolerance. Results: A total of 131 MR studies in 79 patients were performed, with a total of 157 study ears. Sixty-one patients (77%) had unilateral devices. Four patients (5%) underwent MRI with ABI magnets in place. Sixteen patients (20%) had MRI-compatible devices that did not require a head wrap. There were no instances of device stimulation, device malfunction, or excessive heating of the receiver-stimulator package. Magnet tilt requiring manual repositioning occurred during seven studies (4.5%) and magnet displacement requiring operative intervention occurred during seven studies (4.5%). Significant pain where imaging had to be discontinued occurred during three episodes (2%). No adverse events were noted among patients who underwent MRI with an MRI-compatible magnet. Conclusions: MRI with CI or ABI magnets in place is associated with a low prevalence of adverse events when performed in a controlled setting. Many partial magnet displacements can be corrected with firm manual pressure. Devices with magnets that align with the field within their housing were not associated with any adverse events and do not require immobilization of the magnet during the scan. These may be valuable in patients with known or anticipated need for MRI.

Objectives: To evaluate blood–labyrinth barrier permeability using delayed gadolinium enhanced three-dimensional fluid-attenuated inversion recovery (3D-FLAIR) in patients with untreated sporadic vestibular schwannoma (VS) to interrogate the etiopathogenesis of progressive sensorineural hearing loss. Design: Prospective case series. Setting: Single institution tertiary care center. Participants: Patients with previously untreated small to medium-sized unilateral VS undergoing 3D-FLAIR imaging 10 minutes (immediate) and 5 to 8 hours (delayed) after administration of intravenous gadolinium. Main Outcome Measures: Comparison of cochlear and vestibular signal intensity ratios (SIRs) across immediate and delayed images and across the tumor and nontumor ear. Results: Six of eight (75%) patients demonstrated asymmetric enhancement of inner ear structures on delayed contrast-enhanced imaging. Delayed mean cochlea and vestibule SIRs were significantly greater than immediate SIRs (cochlea: 1.91 versus 1.21 [p = 0.02]; vestibule 1.74 versus 1.15 [p = 0.02]). A higher vestibule SIR was statistically significantly associated with poorer pure-tone average and word recognition scores (p = 0.001). Conclusion: Ears with VS exhibited increased enhancement on delayed 3D FLAIR imaging. These findings suggest that alterations in blood–labyrinth barrier permeability may explain progressive sensorineural hearing loss in a subset of patients with untreated VS.

ObjectiveAlthough granulomatosis with polyangiitis (GPA; Wegener’s granulomatosis) is classically characterized by systemic disease involving the kidneys and airway, approximately 10% of patients who have it present with isolated central nervous system disease. When involving the skull base, GPA frequently mimics more common pathology, resulting in diagnostic challenges and delay. The primary objective of this study is to characterize the cranial base manifestations of GPA, highlighting aspects most relevant to the skull base surgeon.Study DesignRetrospective review.SettingTertiary academic referral center.Subjects and MethodsRetrospective analysis of all patients with skull base GPA treated at a tertiary referral center from January 1, 1996, to May 1, 2018.ResultsTwenty‐nine patients met inclusion criteria. Twenty‐one (72%) initially presented with skull base symptomatology as their cardinal manifestation of GPA. Twenty‐four (82%) presented with cranial neuropathy at some point in their disease course. The trigeminal nerve was most commonly involved (12 of 24, 50%), followed by the facial (11 of 24, 46%) and optic (8 of 24, 33%) nerves. Eighteen patients reported hearing loss attributed to the GPA disease process, presenting as conductive, sensorineural, or mixed. The most common locations for GPA‐derived inflammatory skull base disease on imaging included the cavernous sinus (12 of 29, 41%) and the orbit (7 of 29, 24%).ConclusionEstablishing the diagnosis of skull base GPA remains challenging. Cranial neuropathy is diverse in presentation and often mimics more common conditions. Imaging findings are also unpredictable and frequently nonspecific. Careful review of patient history, clinical presentation, serology and biopsy results, and imaging can reveal important clues toward the diagnosis.

Objective: The incidence of sporadic vestibular schwannoma (VS) has increased significantly over recent decades. The rising incidence of VS has been largely attributed to the increasing use of magnetic resonance imaging (MRI), especially with regard to incidentally diagnosed tumors. However, no study to date has directly investigated this supposed etiology beyond the observation that VS incidence rates have risen in the post-MRI era. Therefore, the primary objective of the current study was to characterize the incidence of head MRIs over the previous two decades in Olmsted County, Minnesota and compare this trend to the incidence of asymptomatic, incidentally diagnosed VS over the same time period. Study Design: Population-based incidence study. Setting/Patients: Using the unique resources of the Rochester Epidemiology Project, procedure codes for head MRIs and diagnostic codes for VS among residents of Olmsted County, Minnesota between Jan 1, 1995 and Dec 31, 2016 were retrieved. Incidence rates of head MRI and incidentally diagnosed VS were calculated on a per-year basis. Results: A total of 43,561 head MRIs among 30,002 distinct persons were identified from 1995 to 2016. The incidence of head MRI significantly increased between 1995 and 2003 (p < 0.001), but remained stable between 2004 and 2016 (p = 0.14). Over the same time interval, 25 cases of incidentally diagnosed VS were identified. The incidence of asymptomatic VS increased over time from 0.72 per 100,000 person-years between 1995 and 1999 to 1.29 between 2012 and 2016 (p = 0.058). No plateauing of incidence rates was observed in incidental tumors over the study period. The size of incidentally diagnosed tumors did not change over the study period (p = 0.93), suggesting that the increasing incidence of asymptomatic tumors is not explained by improved diagnostic capability of more recent MRI studies. Conclusions: Despite the plateauing of head MRI incidence rates after 2004, the incidence of asymptotic, incidentally diagnosed VS continued to increase. Our findings suggest that there may be additional contributory etiologies for the rising incidence of VS beyond greater detection alone.

ObjectiveIgG4‐related disease (IgG4‐RD) is a recently recognized disease characterized by fibroinflammatory infiltrates rich in IgG4+ plasma cells that can present as isolated tumor‐like lesions of the head and neck. The objective of the current study was to describe the cranial base manifestations of IgG4‐RD.MethodsReview of all cases at three tertiary‐referral centers since disease description in 2003.ResultsEleven patients were identified at a median age at presentation of 58 years (IQR, 38–65; 55% male). Ten (91%) patients had isolated skull base masses without systemic disease. Cranial neuropathies were commonly observed in the abducens (45%), trigeminal (18%), and facial nerves (18%). Lesions frequently involved the cavernous sinus (55%; 6/11) with extension to the petroclival junction in 50% (3/6). Infiltration of the internal auditory canal was present in 27% (3/11) with one case demonstrating erosion of the bony labyrinth. Preliminary clinical diagnoses commonly included nasopharyngeal cancer, pituitary macroadenoma, cholesteatoma, and meningioma / multiple meningioma syndrome. Local biopsy demonstrated >30 IgG4‐positive plasma cells per high‐powered field or an IgG4:IgG ratio greater than 40% in all cases. Rapid and durable clinical improvement was seen in 91% following corticosteroid and rituximab therapy.ConclusionsIgG4‐RD nonspecifically presents as a rare cause of the skull base mass. Often presenting without concomitant systemic disease, local diagnostic biopsies are required. Obtaining adequate tissue specimen is complicated by densely fibrotic cranial base lesions that are frequently in close proximity to critical neurovascular structures. Primary medical therapy with corticosteroids and rituximab is effective in most patients.Level of Evidence4 Laryngoscope, 130:2574–2580, 2020