External auditory canal cholesteatoma: clinical and imaging spectrum

BACKGROUND AND PURPOSE: Cholesteatoma is an inflammatory lesion of the temporal bone that uncommonly involves the external auditory canal (EAC). In this large case series, we aimed to define its imaging features and to determine the characteristics most important to its clinical management. METHODS: Thirteen cases of EAC cholesteatoma (EACC) were retrospectively reviewed. Clinical data were reviewed for the history, presentation, and physical examination findings. High-resolution temporal bone CT scans were examined for a soft-tissue mass in the EAC, erosion of adjacent bone, and bone fragments in the mass. The middle ear cavity, mastoid, facial nerve canal, and tegmen tympani were evaluated for involvement. RESULTS: Patients presented with otorrhea, otalgia, or hearing loss. Eight cases were spontaneous, and five were postsurgical or post-traumatic. CT imaging in all 13 cases showed a soft-tissue mass with adjacent bone erosion. Intramural bone fragments were identified in seven cases. This mass most often arose inferiorly (n = 8) or posteriorly (n = 8), but it was circumferential in two cases. We noted middle ear extension (n = 5), mastoid involvement (n = 4), facial canal erosion (n = 2), and tegmen tympani dehiscence (n = 1). CONCLUSION: Temporal bone CT shows EACC as a soft-tissue mass within the EAC, with adjacent bone erosion. Bone fragments may be present within the mass. The cholesteatoma may extend into the mastoid or middle ear, or it may involve the facial nerve canal or tegmen tympani. Recognition of this entity and its possible extension is important because it may influence clinical management.     

Primary jugular foramen meningioma: imaging appearance and differentiating features

OBJECTIVE: Primary jugular foramen meningiomas behave differently from meningiomas arising elsewhere. The differences have important clinical, imaging, and surgical implications. We reviewed the imaging appearances of primary jugular foramen meningiomas and evaluated them for features that might assist in differentiating them from other common jugular foramen lesions. MATERIALS AND METHODS: A retrospective review identified five cases of primary jugular foramen meningioma. We defined it as primary when it was centered in the jugular foramen and secondary when it was centered in the posterior fossa with secondary extension into the jugular foramen. Secondary jugular foramen meningiomas were excluded from this study. Eight cases of jugular foramen paraganglioma and 10 cases of jugular foramen schwannoma were reviewed for comparison. RESULTS: Primary meningioma was characterized by centrifugal infiltration surrounding the skull base (5/5), a permeative-sclerotic appearance to the bone margins of the jugular foramen (5/5), and prominent dural tails (5/5). Flow voids were absent in all cases. Paraganglioma showed localized skull base infiltration, with predominant superolateral spread into the middle ear cavity (8/8). Flow voids and permeative destruction of the bone margins of the jugular foramen were typical. Schwannoma caused expansion of the jugular foramen with scalloped well-corticate bone margins, without skull base infiltration. CONCLUSION: Primary jugular foramen meningioma is characterized by extensive skull base infiltration. A centrifugal pattern of spread, a permeative-sclerotic appearance of the bone margins of the jugular foramen, the presence of dural tails, and an absence of flow voids are particularly important features that assist in differentiating primary jugular foramen meningioma other more common jugular foramen lesions.     

The role of high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in the diagnosis of preoperative and postoperative complications caused by acquired cholesteatomas

The role of high-resolution computed tomography (HRCT) and magnetic resonance imaging (MRI) in the diagnosis of preoperative and postoperative complications caused by acquired cholesteatomas will be described in this paper. The pre- and postoperative imaging of the temporal bone was performed with HRCT and MRI.HRCT and MRI were performed in the axial and coronal plane. MRI was done with T2 weighted and T1 weighted sequences both before and after the intravenous application of contrast material. All imaging findings were confirmed clinically or surgically. The preoperative cholesteatoma-caused complications depicted by HRCT included bony erosions of the ossicles, scutum, facial canal in the middle ear, tympanic walls including the tegmen tympani, and of the labyrinth. The preoperative cholesteatoma-caused complications depicted by MRI included signs indicative for labyrinthitis, and brain abscess. Postoperative HRCT depicted bony erosions caused by recurrent cholesteatoma,bony defects of the facial nerve and of the labyrinth, and a defect of the tegmen tympani with a soft tissue mass in the middle ear. Postoperative MRI delineated neuritis of the facial nerve, labyrinthitis, and a meningo-encephalocele protruding into the middle ear. HRCT and MRI are excellent imaging tools to depict either bony or soft tissue complications or both if caused by acquired cholesteatomas. According to our findings and to the literature HRCT and MRI are complementary imaging methods to depict pre- or postoperative complications of acquired cholesteatomas if these are suspected by clinical examination.     

Imaging findings of cochlear nerve deficiency

BACKGROUND AND PURPOSE: High-resolution T2-weighted fast spin-echo MR imaging provides excellent depiction of the cisternal and intracanalicular segments of the vestibulocochlear and facial nerves. Absence or reduction in caliber of the cochlear nerve (deficiency) has been described in association with congenital sensorineural hearing loss (SNHL). Depiction of cochlear nerve integrity may be important for diagnosis and management of SNHL. METHODS: We retrospectively reviewed high-resolution T2-weighted fast spin-echo MR images of 22 patients examined for SNHL who had deficiency of the cochlear nerve. Images were evaluated for the presence and comparative size of the component nerves (facial, cochlear, superior vestibular, and inferior vestibular nerves), relative size of the internal auditory canal (IAC), and any associated inner ear abnormalities. The clinical history, results of the clinical examination, and audiometric findings were reviewed for each patient. RESULTS: Deficiency of the cochlear nerve was observed in 12 patients with congenital SNHL and in 10 patients with acquired SNHL. Hypoplasia of the IAC was observed in association with congenital deficiency of the cochlear nerve in 11 of 12 patients. Deficiency of the cochlear nerve was observed in association with acoustic schwannoma in two cases and with acquired labyrinthine abnormalities in seven cases. Hypoplasia of the IAC was not observed in association with acquired SNHL. CONCLUSION: Deficiency of the cochlear nerve can be shown by high-resolution T2-weighted fast spin-echo MR imaging. Deficiency may be observed in association with congenital or acquired SNHL and may be important in the assessment of patients for cochlear implantation. Hypoplasia of the IAC is an indicator of congenital cochlear nerve deficiency.     

Barotrauma presenting as temporal lobe injury secondary to temporal bone rupture

We present the case of a scuba diver who experienced acute ear pain during ascent from a dive. CT imaging was performed because of severe unrelenting headache. Blood and gas was identified within the epidural space of the middle fossa and over the petrous bone, as well as hemorrhage within the adjacent temporal lobe. To the best of our knowledge, this is the first case of CT-documented barotrauma affecting the brain as a result of middle-ear gas rupturing through the tegmen tympani.     

儿童先天性感音神经性聋的影像学评估

目的:研究先天性感音神经性聋(SNHL)患儿的颞骨影像,分析内耳畸形的发生率及其类型,了解内耳畸形与耳蜗神经发育的关系,探讨部分患者是否仅行CT检查即可而无需进行MRI检查.方法:回顾性分析101例临床拟诊先天性SNHL的儿童颞骨CT和MRI影像资料,观察其内耳、蜗神经的结构.101例中,95例为重度或极重度双侧性SNHL,6例为单侧性SNHL.结果:196例患耳中,内耳畸形66耳:耳蜗不发育3耳;耳蜗发育不良5耳;不完全分隔I型7耳,不完全分隔II型10耳;前庭导水管扩大24耳;蜗神经不发育或发育不良19耳.10耳内听道狭窄均伴有蜗神经畸形.单侧性聋的6例患者中,均有蜗神经畸形.130例CT示内耳正常者,MRI也示蜗神经正常.结论:影像学诊断先天性重度或极重度双侧性SNHL内耳畸形发生率(31.6%)较单侧性SNHL者(100%)低,较为常见的畸形是前庭导水管扩大和耳蜗畸形,内耳畸形严重程度与蜗神经发育异常的发生率有一定相关性;对于双侧性耳聋者,CT诊断有严重内耳畸形者必须行MRI扫描,以排除蜗神经发育畸形;CT示耳蜗结构正常且内听道无狭窄者可无需行MRI扫描;单侧性耳聋者必须同时行CT和MRI扫描.     

Differentiation of cerebellopontine angle neuromas and meningiomas with MR imaging

Postcontrast CT of the temporal bone is the neuroradiological study of choice for investigation of cerebellopontine angle (CPA) and internal auditory canal (IAC) lesions. Nonenhancing or small lesions may need CT combined with air or metrizamide cisternography for their detection. Magnetic resonance (MR) imaging has shown interesting capabilities as a noninvasive study for the visualization of the IAC, the neural bundle entering the canal, the brain stem, and cerebellum. In the present series of 24 cases, MR imaging detected the lesion in all 11 verified tumors. We feel that MR can replace invasive air and metrizamide cisternography in the diagnosis of CPA lesions and can help in the differentiation between acoustic neuromas and meningiomas.     

Common crus aplasia: diagnosis by 3D volume rendering imaging using 3DFT-CISS sequence

AIM: The purpose of this study was to evaluate the findings of three-dimensional (3D) volume rendering (VR) imaging in common crus aplasia (CCA) of the inner ear. MATERIALS AND METHODS: Using 3D VR imaging of temporal bone constructive interference in steady state (CISS) magnetic resonance (MR) images, we retrospectively reviewed seven inner ears of six children who were candidates for cochlear implants and who had been diagnosed with CCA. As controls, we used the same method to examine 402 inner ears of 201 patients who had no clinical symptoms or signs of sensorineural hearing loss. Temporal bone MR imaging (MRI) was performed with a 1.5 T MR machine using a CISS sequence, and VR of the inner ear was performed on a work station. Morphological image analysis was performed on rotation views of 3D VR images. RESULTS: In all seven cases, CCA was diagnosed by the absence of the common crus. The remaining superior semicircular canal (SCC) was normal in five and hypoplastic in two inner ears, while the posterior SCC was normal in all seven. One patient showed bilateral symmetrical CCA. Complicated combined anomalies were seen in the cochlea, vestibule and lateral SCC. CONCLUSION: 3D VR imaging findings with MR CISS sequence can directly diagnose CCA. This technique may be useful in delineating detailed anomalies of SCCs.     

Direct sagittal CT in the evaluation of temporal bone disease

The human temporal bone is an extremely complex structure. Direct axial and coronal CT sections are quite satisfactory for imaging the anatomy of the temporal bone; however, many relationships of the normal and pathologic anatomic detail of the temporal bone are better seen with direct sagittal CT sections. The sagittal projection is of interest to surgeons, as it has the advantage of following the plane of surgical approach. This article describes the advantages of using direct sagittal sections for studying various diseases of the temporal bone. The CT sections were obtained with the aid of a new head holder added to our GE CT 9800 scanner. The direct sagittal projection was found to be extremely useful for evaluating diseases involving the vertical segment of the facial nerve canal, vestibular aqueduct, tegmen tympani, sigmoid sinus plate, sinodural angle, carotid canal, jugular fossa, external auditory canal, middle ear cavity, infra- and supralabyrinthine air cells, and temporomandibular joint.     

Pneumosinus dilatans in anterior skull base meningiomas

Introduction

Skull base meningiomas are often missed on non-contrast CT or MR examinations due to their close proximity to bone and low lesion to brain contrast. The purpose of this study is to illustrate that pneumosinus dilatans can be an indicator of anterior skull base meningiomas.

Methods

A retrospective search of the radiology information system and picture archiving and computing system database was performed. Search terms were “meningioma” in association with “pneumosinus dilatans.” Medical records and imaging studies were reviewed independently by two experienced neuroradiologists and were read in consensus. We recorded the patient age at the time of discovery of the meningioma, main presenting symptom(s), location of the tumor, and imaging characteristics. We also performed a comparative literature search for pneumosinus dilatans and its association with meningiomas.

Results

Ten patients (six women; four men) were identified in whom a meningioma of the anterior skull base was associated with a pneumosinus dilatans. Three patients had multiple meningiomas, so a total of 14 intracranial tumors were identified. Mean age at discovery was 59 years with an age range of ±20 years. All meningiomas were diagnosed by MRI and/or CT.

Conclusion

Pneumosinus dilatans can be a helpful sign to indicate the presence of a meningioma of the anterior skull base.     

Middle ear cholesteatoma extending into the petrous apex: evaluation by CT and MR imaging

CT and MR imaging findings were reviewed in four cases of acquired cholesteatoma of the middle ear that extended medially into the petrous apex and middle cranial fossa. In one case the lesion further extended anteromedially into the sphenoid sinus. CT demonstrated the lesions as nonenhancing hypodense masses with bone destruction, extending medially from the middle ear cavity to the petrous apex region. On MR imaging, the lesion was slightly hypointense relative to brain on T1-weighted images and hyperintense on T2-weighted images. MR imaging clearly delineated the extraaxial location of the lesion and associated brain displacement. The medial extension of the cholesteatomas seems to have proceeded via a detour around the bony labyrinth into the petrous apex region by following normal pathways of temporal bone pneumatization.     

Review of congenital inner ear abnormalities on CT temporal bone

The aetiology of profound hearing loss in children is complex and multifactorial. Congenital inner ear abnormality is a major cause of hearing loss in children. CT temporal bone imaging is the modality of choice in the investigation of hearing loss. Recognising the congenital abnormalities of the inner ear guides the clinician's management of the condition. This pictorial essay illustrates the congenital abnormalities of the inner ear on high resolution CT temporal bone images and correlation with developmental arrest during embryology.     

Prevalence of Internal Auditory Canal Diverticulum and Its Association with Hearing Loss and Otosclerosis

BACKGROUND AND PURPOSE:Focal low-attenuation outpouching or diverticulum at the anterolateral internal auditory canal is an uncommon finding on CT of the temporal bone. This finding has been described as cavitary otosclerosis in small case reports and histology series. The purpose of this study was to establish the prevalence of internal auditory canal diverticulum and its association with classic imaging findings of otosclerosis and/or hearing loss.MATERIALS AND METHODS:Temporal bone CT scans of 807 patients, obtained between January 2013 and January 2016, were retrospectively reviewed to identify internal auditory canal diverticula and/or classic imaging findings of otosclerosis. Clinical evaluations for hearing loss were reviewed for patients with internal auditory canal diverticula and/or otosclerosis.RESULTS:Internal auditory canal diverticula were found in 43 patients (5%); classic otosclerosis, in 39 patients (5%); and both findings, in 7 patients (1%). Most temporal bones with only findings of internal auditory canal diverticula (91%) demonstrated hearing loss, with 63% of this group demonstrating sensorineural hearing loss. The hearing loss classification distribution was significantly different (P < .01) from that in the classic otosclerosis group and in the group with both diverticula and otosclerosis.CONCLUSIONS:Internal auditory canal diverticula are not uncommon on CT examinations of the temporal bone and most commonly occur without classic imaging findings of otosclerosis. These lesions are associated with sensorineural hearing loss, and referral for hearing evaluation may be appropriate when present.

A focal low-attenuation notch or diverticulum within the temporal bone continuous with the internal auditory canal (IAC) is an unusual finding on imaging studies of the temporal bone. Several histologic and imaging case reports refer to this finding as a form of cavitary otosclerosis^1–4 and even suggest that the presence is associated with advanced disease.³Otosclerosis is an osteodystrophic disorder of the otic capsule, resulting in abnormal resorption of endochondral bone and deposition of abnormal vascular bone. Otosclerosis usually appears in the third-to-fifth decades of life, and most commonly affects women. Clinical otosclerosis is present in <1% of the population, though it has been reported in up to 11% of the population on histology performed at postmortem examination.⁵ On CT of the temporal bone, otosclerosis commonly appears as lucent or hypodense bone surrounding the otic capsule, often limited to the region anterior to the oval window. This process results in either conductive hearing loss (CHL) due to fixation of the stapes footplate or mixed conductive and sensorineural hearing loss (SNHL) due concomitant otic capsule involvement. Otosclerosis presenting with only SNHL in the absence of CHL is rare and is often called “cochlear otosclerosis.”^5–9Establishing the significance of the IAC diverticulum or notch is important for both the radiologist and referring physician in guiding clinical management. Determining the relationship of this lesion to classic imaging findings of otosclerosis could also be helpful in the understanding of otosclerosis and the spectrum of clinical presentations. Therefore, the purpose of this study was the following: 1) to determine the prevalence of IAC diverticula at our institution, and 2) to explore potential associations with otosclerosis and hearing loss in patients identified with an IAC diverticulum.     

Magnetic resonance imaging spectrum of spinal meningioma

PurposeTo evaluate magnetic resonance (MR) imaging findings of spinal meningioma and to determine the radiological subtypes based on the MR imaging findings and their respective clinical features.Material and methodsData for 105 patients with surgically treated and histopathologically diagnosed spinal meningiomas at our hospital between May 1, 2003 and May 1, 2017 were evaluated in this study. Two radiologists reviewed the characteristics of spinal meningiomas on MR images and categorized the spinal meningiomas into subtypes based on MR imaging findings.ResultsMost spinal meningiomas showed higher signal intensity than that of the spinal cord but lower than that of the subcutaneous fat on T2-weighted images (WI). 56 cases (54%) showed adjacent spinal cord signal changes. Meningiomas could be categorized according to MR imaging findings into type A: dural-based tumors with a homogeneous signal intensity and intense contrast enhancement (81 cases, 77%); type B: round or oval-shaped tumors with an internal hypointense portion on T2-weighted images (18 cases, 17%); type C: en plaque tumors (three cases, 3%); and type D: tumors with unusual findings and a heterogeneous appearance (three cases, 3%). All type C patients showed spinal cord signal changes.ConclusionsSpinal meningioma showed slightly high signal intensity rather than high signal intensity on T2-weighted images. Spinal cord signal changes were present in more than half of the cases. Clinical differences were observed among the different MR imaging types.     

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.     

MR imaging of the internal auditory canal and inner ear at 3T: comparison between 3D driven equilibrium and 3D balanced fast field echo sequences

OBJECTIVE: To compare the use of 3D driven equilibrium (DRIVE) imaging with 3D balanced fast field echo (bFFE) imaging in the assessment of the anatomic structures of the internal auditory canal (IAC) and inner ear at 3 Tesla (T). MATERIALS AND METHODS: Thirty ears of 15 subjects (7 men and 8 women; age range, 22-71 years; average age, 50 years) without evidence of ear problems were examined on a whole-body 3T MR scanner with both 3D DRIVE and 3D bFFE sequences by using an 8-channel sensitivity encoding (SENSE) head coil. Two neuroradiologists reviewed both MR images with particular attention to the visibility of the anatomic structures, including four branches of the cranial nerves within the IAC, anatomic structures of the cochlea, vestibule, and three semicircular canals. RESULTS: Although both techniques provided images of relatively good quality, the 3D DRIVE sequence was somewhat superior to the 3D bFFE sequence. The discrepancies were more prominent for the basal turn of the cochlea, vestibule, and all semicircular canals, and were thought to be attributed to the presence of greater magnetic susceptibility artifacts inherent to gradient-echo techniques such as bFFE. CONCLUSION: Because of higher image quality and less susceptibility artifacts, we highly recommend the employment of 3D DRIVE imaging as the MR imaging choice for the IAC and inner ear.     

Overlapping thin-section fast spin-echo MR of the large vestibular aqueduct syndrome.

PURPOSETo evaluate a high-resolution, thin-section fast spin-echo MR imaging technique of the inner ear to identify the large vestibular aqueduct syndrome seen on temporal bone CT scans.METHODSWe retrospectively reviewed the temporal bone CT scans of 21 patients with hearing loss and enlarged bony vestibular aqueducts by CT criteria. High-resolution fast spin-echo MR imaging was then performed on these patients using dual 3-inch phased-array receiver coils fixed in a temporomandibular joint holder and centered over the temporal bones. MR imaging included axial and oblique sagittal fast spin-echo sequences. The diameter of the midvestibular aqueduct on CT scans and the signal at the level of the midaqueduct on MR images were measured on axial sequences, then compared. High-resolution MR imaging with the same protocol was performed in 44 control subjects with normal ears, and similar measurements were taken.RESULTSThe average size of the enlarged bony vestibular aqueduct on CT scans was 3.7 mm, and the average width of the signal from within the enlarged aqueduct on MR images was 3.8 mm. Statistical analysis showed excellent correlation. MR images alone displayed the enlarged extraosseous endolymphatic sac, which accompanies the enlarged aqueduct in this syndrome. Five ears in three patients with enlarged bony vestibular aqueducts on CT scans showed no evidence of an enlarged endolymphatic duct or sac on MR images. An enlarged endolymphatic sac was seen on MR images in one patient with a bony vestibular aqueduct, which had normal measurements on CT scans. MR imaging alone identified a single case of mild cochlear dysplasia (Mondini malformation). In the 88 normal ears studied, the average size of the endolymphatic sac at its midpoint between the common crus and the external aperture measured on MR images was 0.8 mm (range, 0.5 to 1.4 mm). In 25% of the normal ears, no signal was seen from within the vestibular aqueduct.CONCLUSIONThin-section, high-resolution fast spin-echo MR imaging of the inner ear is complementary to CT in studying patients with the large vestibular aqueduct syndrome, as MR imaging better displays the soft tissue and fluid of the membranous labyrinth.     

Multiple pulmonary metastases from intracranial meningioma: MR imaging findings (case report)

Extracranial metastases from meningioma are very rare and among those the lungs are the most common metastatic site. In the literature, pulmonary metastases of meningiomas have been emphasized on their rarity, non-specific imaging findings, and cytologic features. Some definitive MR imaging features of intracranial meningiomas have been described. However, MR imaging findings of the lung metastases of meningiomas have not been investigated with regard to these diagnostic imaging features. In this report, similarities between MR imaging features of primary intracranial meningioma and its rare lung metastases are presented.     

MR imaging of cerebellopontine angle and internal auditory canal lesions at 1.5 T

The high-field, thin-section (3-5 mm) MR imaging characteristics of 49 cerebellopontine angle and internal auditory canal lesions were reviewed. The diverse abnormalities include 20 acoustic neurinomas, eight neurinomas of other cranial nerves (six involving the fifth cranial nerve and two involving cranial nerves IX-XI), seven meningiomas, five subdural fluid collections, four brainstem tumors with exophytic components, three glomus jugulare tumors, one epidermoid tumor, and one basilar artery aneurysm. T1-, T2-, and proton-density-weighted images were obtained in all cases. T1-weighted images most accurately showed the margins of the seventh and eighth nerves in the internal auditory canal and were most sensitive in detecting small tumors in the cerebellopontine angle. Differentiation of meningioma from acoustic neurinoma by MR was provided most reliably by separation of the meningioma from the porus acusticus and seventh and eighth nerves and not by signal-intensity differences. A hypointense vascular rim was noted on MR in seven of 13 extracanalicular acoustic tumors and in three of seven meningiomas.     

Dumbbell schwannomas of the internal auditory canal

BACKGROUND AND PURPOSE: Benign tumors of the internal auditory canal (IAC) may leave the confines of the IAC fundus and extend into inner ear structures, forming a dumbbell-shaped lesion. It is important to differentiate dumbbell lesions, which include facial and vestibulocochlear schwannomas, from simple intracanalicular schwannomas, as surgical techniques and prognostic implications are affected. In this article, the imaging and clinical features of these dumbbell schwannomas are described. METHODS: A dumbbell lesion of the IAC is defined as a mass with two bulbous segments, one in the IAC fundus and the other in the membranous labyrinth of the inner ear or the geniculate ganglion of the facial nerve canal, spanned by an isthmus. Twenty-four patients with dumbbell lesions of the IAC had their clinical and imaging data retrospectively reviewed. Images were evaluated for contour of the mass and extension into the membranous labyrinth or geniculate ganglion. RESULTS: Ten of 24 lesions were facial nerve dumbbell lesions. Characteristic features included an enhancing "tail" along the labyrinthine segment of the facial nerve and enlargement of the facial nerve canal. Dumbbell schwannomas of the vestibulocochlear nerve (14/24) included transmodiolar (8/14), which extended into the cochlea, transmacular (2/14), which extended into the vestibule, and combined transmodiolar/transmacular (4/14) types. CONCLUSION: Simple intracanalicular schwannomas can be differentiated from transmodiolar, transmacular, and facial nerve schwannomas with postcontrast and high-resolution fast spin-echo T2-weighted MR imaging. Temporal bone CT is reserved for presurgical planning in the dumbbell facial nerve schwannoma group.