Imaging of dental infections.

Dental infections are a common presentation in the emergency department (ED). To help guide clinical management for these infections, the radiologist must be familiar with the anatomy of the oral cavity and neighboring structures, the range of appearance of dental infections, and the routes along which they may spread. Computed tomography (CT) is often performed when severe dental infections are suspected. This pictorial essay reviews the anatomy pertinent to the imaging evaluation of dental infections and depicts a spectrum of pathology that may be encountered, ranging from simple dentoalveolar infections to complex multispatial infections.

Midbrain Ischemic Strokes Presenting as Isolated Internuclear Opthalmoplegia.

Stroke can present with unique neurologic symptoms, which can be used to help determine the location of the stroke. Internuclear ophthalmoparesis (INO), also known as internuclearophthalmoplegia, is a distinct gaze abnormality with impaired horizontal eye movements with compromised adduction of the affected eye, and abduction nystagmus of the contralateral eye. Infarcts involving the medial longitudinal fasciculus in either the pons or midbrain can result in INO. We present two cases of midbrain ischemic stroke, which presented as isolated INO. The midbrain has a unique and intricate vascular supply including branches from the basilar, superior cerebellar, posterior cerebral, posterior communicating, anterior choroidal, and posterior choroidal arteries, which is reviewed. Infarcts involving the paramedian midbrain, which is supplied by short circumferential arteries and penetrating branches arising from the posterior cerebral artery and superior cerebellar artery, can result in INO.

Proposed Grading System for Posterior Atlantooccipital Membrane Complex Injuries on Cervical Magnetic Resonance Imaging.

BACKGROUND: The posterior atlantooccipital membrane complex consists of the posterior atlantooccipital membrane and posterior atlantoaxial membrane. Posttraumatic, posterior atlantooccipital membrane complex injuries may have varied appearances on cervical magnetic resonance imaging. The purpose of this study was to identify the different types of posterior atlantooccipital membrane complex injuries that occur in trauma patients. METHODS: Patients who suffered a posterior atlantooccipital membrane complex injury were identified retrospectively using key word searches of cervical magnetic resonance imaging reports between 2013 and 2020 using Nuance mPower software. All relevant imaging studies were reviewed by 2 neuroradiologists. A description of the location and type of posterior atlantooccipital membrane complex injury was recorded, along with additional osteoligamentous trauma of the craniocervical junction and relevant clinical history. RESULTS: Forty-one patients were identified with acute posterior atlantooccipital membrane complex injury. Four distinct patterns of posterior atlantooccipital membrane complex injury were observed. CONCLUSIONS: A grading system for posterior atlantooccipital membrane complex injuries is proposed on the basis of these data: grade 1-edema confined to the posterior atlantooccipital and atlantoaxial membrane; grade 2-edema confined to the posterior atlantooccipital and atlantoaxial membrane and ligamentum nuchae; grade 3-stripping injury of the posterior atlantooccipital membrane with C1-C2 dorsal epidural hematoma; and grade 4-frank disruption of the posterior atlantooccipital membrane at C1 with edema in the remaining posterior atlantooccipital membrane complex.

Imaging Review of Angiotensin-Converting Enzyme Inhibitor-Induced Angioedema of the Head and Neck.

Angiotensin-converting enzyme inhibitors (ACE-i) are commonly used medications to treat hypertension and congestive heart failure. Angioedema is a well-established side effect of ACE-i and most commonly manifests as swelling of the mucosal and extra-mucosal soft tissues in the head and neck. CT with contrast is generally used to evaluate for airway compromise and to exclude other etiologies of edema. Herein we present five cases that illustrate the radiological findings specific to ACE-i-induced angioedema on enhanced CT scans.

Grade III Solitary Fibrous Tumor/Hemangiopericytoma: A Rare Case of a World Health Organization Grade III Anaplastic Hemangiopericytoma.

Solitary fibrous tumors (SFTs) and hemangiopericytomas (HPCs) have been combined into a single designation in the most recent World Health Organization (WHO) guidelines as solitary fibrous tumor/hemangiopericytoma (SFT/HPC). These rare intracranial tumors can present as WHO grade I, II, or III tumors, with the risk of recurrence, metastasis, and mortality worsening with higher-grade tumors. We present a case of a patient with a WHO grade III SFT/HPC with an emphasis on the imaging features that help differentiate this type of tumor from meningiomas, which are much more common and can appear similar. Being able to help differentiate these tumors by their imaging appearance is important to help triage and risk-stratify patient management decisions.

The Medial Longitudinal Fasciculus and Internuclear Opthalmoparesis: There's More Than Meets the Eye.

Background and purpose The classic sign of a lesion in the medial longitudinal fasciculus is internuclear opthalmoplegia. However, clinical presentation may vary depending on the type of pathology and the lesion location. The purpose of this study was to identify and classify the different lesions of the medial longitudinal fasciculus on MRI and review their clinical presentations. We also offer an overview of the pertinent imaging anatomy of the medial longitudinal fasciculus. Materials and methods Patients with an abnormality affecting the medial longitudinal fasciculus were identified retrospectively using the keyword 'medial longitudinal fasciculus' included in radiology reports between 2010 and 2018 using the Nuance mPower software (Nuance Communications, Burlington, MA). The brain MRI examinations of these patients were reviewed by two neuroradiolgists. Detailed description of lesion location within the medial longitudinal fasciculus, pathology type, additional lesions, and clinical presentations were recorded along with pertinent demographic information. Results Five men and four women were identified with lesions in the medial longitudinal fasciculus on brain MRI. Five patients demonstrated demyelination in the medial longitudinal fasiculus and four patients demonstrated findings of an acute cerebrovascular accident. Two-thirds of medial longitudinal fasiculus lesions were located in the upper, mid, or lower pons with the remaining located in the midbrain. Of the patients presenting with a cerebrovascular accident, there was little to no additional evidence of acute stroke elsewhere in the brain. All patients were clinically symptomatic with 89% of patients demonstrating extraocular muscle dysfunction at presentation and 78% of patients experiencing dizziness. Additional symptoms included headache, weakness, and gait instability. Conclusions  Lesions involving the medial longitudinal fasiculus may not always present with the classic sign of internuclear opthalmoplegia. Variations in lesion location may result in diplopia rather than internuclear opthalmoplegia, and additional brain lesions may produce clinical symptoms that confound extraocular muscle dysfunction. Lesions affecting the often-overlooked vestibular and otolithic reflexes, which run in the medial longitudinal fasiculus, may result in dizziness/weakness and mask the classic internuclear opthalmoplegia symptoms. The radiologist should carefully inspect the medial longitudinal fasiculus in all patients regardless of the supportive clinical history of extraocular muscle dysfunction since symptoms may be more general than classically described.

Langerhans Cell Histiocytosis Presenting as Progressively Worsening Neck Pain: A Case Report With a Review of Literature.

A 29-year-old female with past medical history of chronic serous otitis media presented with worsening neck stiffness and pain over a period of 2 weeks. The patient described non-specific symptoms that were localized to the right side of her neck. She presented to the hospital only when the pain was so extreme that it limited her range of motion. The differential for acute neck pain without fever, chills or any inciting trauma is vast. They include medical emergencies such as meningitis, acute coronary syndromes and extend to rheumatologic diseases or simply musculoskeletal strain. On review of systems, she denied dizziness, headache, vision changes, dysphagia, or other facial pain. Based on the severity of her pain, she underwent a Computed Tomography scan of the neck, which was concerning for erosive calavarial lesions. Further imaging revealed multiple lytic foci and erosions from the right maxillary sinus to the right mandible to the C1 vertebra. Following requisite surgical intervention, she was found to have Langerhans cell histiocytosis, a rare disease of myeloid cells, usually affecting pediatric populations. Little is known about the adult manifestations of Langerhans Cell Histiocytosis. This review contributes to broadening the literature on this topic which can present with complaints as typical as neck pain.

Necrotic Primary Central Nervous System Lymphoma in an Immunocompetent Patient: A Case Report and Literature Review.

Primary lymphoma that arises de novo from the central nervous system (CNS) is most commonly a non-Hodgkin's B-cell lymphoma and by definition lacks the presence of disease outside the CNS. It demonstrates a characteristic imaging appearance on computed tomography (CT) and magnetic resonance imaging (MRI) exams related to its inherent hypercellularity. On CT, primary CNS lymphoma (PCNSL) demonstrates a hyperdense appearance; on MRI, it commonly demonstrates restricted water diffusion on diffusion-weighted sequences and homogeneous enhancement on post-contrast sequences. We present a case of primary CNS lymphoma in an immunocompetent patient with progressive necrosis and loss of restricted diffusion on diffusion-weighted imaging (DWI) with an atypical enhancement pattern. We further provide a review of the literature regarding the CT and MRI appearance of primary CNS lymphoma and discuss the role of immune status in determining the imaging characteristics of this disease process.