Mastoid effusion on temporal bone MRI in patients with Bell's palsy and Ramsay Hunt syndrome

Imaging of Pathologies of the Temporal Bone and Middle Ear: Inflammatory Diseases, Their Mimics and Potential Complications-Pictorial Review

Imaging of the temporal bone and middle ear is challenging for radiologists due to the abundance of distinct anatomical structures and the plethora of possible pathologies. The basis for a precise diagnosis is knowledge of the underlying anatomy as well as the clinical presentation and the individual patient's otological status. In this article, we aimed to summarize the most common inflammatory lesions of the temporal bone and middle ear, describe their specific imaging characteristics, and highlight their differential diagnoses. First, we introduce anatomical and imaging fundamentals. Additionally, a point-to-point comparison of the radiological and histological features of the wide spectrum of inflammatory diseases of the temporal bone and middle ear in context with a review of the current literature and current trends is given.

Facial nerve schwannoma: Case report and brief review of the literature

Schwannomas are rare nerve sheath tumors that can occur throughout the body, and are symptomatic based on location, size, and impingement on adjacent structures. These tumors are often benign lesions and occur sporadically or from genetic conditions such as neurofibromatosis. Schwannomas may arise from peripheral nerves, gastrointestinal nerves, spinal nerve roots and cranial nerves. Facial nerve schwannomas arise from cranial nerve VII, commonly involving the geniculate ganglion, labyrinthine segment, and internal auditory canal. While small lesions are asymptomatic, larger lesions can cause facial nerve paralysis, and facial spasms. Lesions in the internal auditory canal can cause hearing loss, tinnitus, vertigo, and otalgia. High-resolution CT imaging and MRI imaging are useful for distinguishing between other pathologies that arise from the same region. High-resolution CT scans can show bony degeneration of nearby structures such as the labyrinth or ossicles. MRI imaging shows hypo intensity on T1 imaging, and hyperintensity on T2 imaging. On T1 postcontrast, enhancement can be homogenous or heterogeneous with cystic degeneration if the lesion is large. Nodular enhancement is commonly seen on facial nerve schwannomas within the internal auditory canal. Vestibular schwannomas involving CN VIII are more common, and appear similar to facial nerve schwannomas, but can be distinguished apart due to growth in the geniculate ganglion and/or the labyrinthine segment. Management of asymptomatic or mild lesions is typically conservative with follow up imaging, and surgery for larger lesions. Here, we present a case of a facial nerve schwannoma in a 57-year-old woman.

Advanced imaging of head and neck infections

When head and neck infection is suspected, appropriate imaging contributes to treatment decisions and prognosis. While contrast-enhanced CT is the standard imaging modality for evaluating head and neck infections, MRI can better characterize the skull base, intracranial involvement, and osteomyelitis, implying that these are complementary techniques for a comprehensive assessment. Both CT and MRI are useful in the evaluation of abscesses and thrombophlebitis, while MRI is especially useful in the evaluation of intracranial inflammatory spread/abscess formation, differentiation of abscess from other conditions, evaluation of the presence and activity of inflammation and osteomyelitis, evaluation of mastoid extension in middle ear cholesteatoma, and evaluation of facial neuritis and labyrinthitis. Apparent diffusion coefficient derived from diffusion-weighted imaging is useful for differential diagnosis and treatment response of head and neck infections in various anatomical sites. Dynamic contrast-enhanced MRI perfusion may be useful in assessing the activity of skull base osteomyelitis. MR bone imaging may be of additional value in evaluating bony structures of the skull base and jaw. Dual-energy CT is helpful in reducing metal artifacts, evaluating deep neck abscess, and detecting salivary stones. Subtraction CT techniques are used to detect progressive bone-destructive changes and to reduce dental amalgam artifacts. This article provides a region-based approach to the imaging evaluation of head and neck infections, using both conventional and advanced imaging techniques.

Features of Audio-Vestibular Deficit and 3D-FLAIR Temporal Bone MRI in Patients with Herpes Zoster Oticus

Herpes zoster oticus (HZO) is characterized by otalgia and erythematous vesicles in the auricle or external auditory canal. Ramsay Hunt syndrome (RHS) can be diagnosed when facial nerve palsy is accompanied by these symptoms of HZO, and in this case, audio-vestibular symptoms such as hearing loss or dizziness often develop. Recently, 3D-fluid-attenuated inversion recovery sequence (3D-FLAIR) magnetic resonance imaging (MRI) has been introduced in order to evaluate the inner ear structure pathology. The purpose of this study was to investigate the audio-vestibular characteristics in correlation with temporal bone MRI findings in HZO patients. From September 2018 to June 2022, 18 patients with HZO participated in the study. Thirteen patients (77%) showed high-signal intensity in the inner ear structures in 4 h post-contrast 3D-FLAIR images. In a bithermal caloric test, the lateral semicircular canal showed high signal intensity in 4 h post-contrast 3D-FLAIR images in 75% of patients with abnormal canal paresis. While the cochlea showed high signal intensity in 4 h post-contrast 3D-FLAIR images in 75% of patients with hearing loss, the vestibulo-cochlear nerve showed enhancement in post-contrast T1-weighted images in only 33% of patients with hearing loss. The present study demonstrates that audio-vestibular deficits are well-correlated with increased signal intensity of the inner ear endorgans in 4 h post contrast 3D-FLAIR MRI.