Both optic neuritis (ON) and optic perineuritis (OPN) are distinct entities with the idiopathic forms having different clinical presentations, imaging appearances, and treatment courses. Additionally, they are both associated with different diseases, each with different underlying pathophysiology and appropriate management. ON is associated with multiple sclerosis, neuromyelitis optica, and myelin oligodendrocyte glycoprotein antibody‐associated disease. OPN is associated with giant cell arteritis and infectious neuritis. In this article, we review these common entities, their etiologies, imaging appearance, mimics, and lesser known vasculitis and rheumatologic associations, to ultimately provide a comprehensive review on ON and OPN.Learning Objective: To describe the distinguishing imaging characteristics of both ON and OPN.

Non-Galenic pial arteriovenous fistulas (NGPAVFs) are very rare in neonates and pose serious risk for morbidity and mortality. NGPAVFs are characterized by a direct arteriovenous connection between a pial artery and a cortical vein without an intervening capillary bed. Lack of a nidus differentiates an arteriovenous fistula from an arteriovenous malformation. In neonates, the clinical presentation and prognosis of NGPAVF are similar to those of the more common vein of Galen aneurysmal malformation, from which it must be differentiated. We report a case of a high-flow, multi-hole variant of a NGPAVF presenting with high-output heart failure with an imaging-focused description. This report discusses how the imaging appearance of an NGPAVF compares with that of other high-flow malformations and includes a brief literature review.Learning Objective: NGPAVF, a rare cerebrovascular malformation, should be included in the differential diagnosis of high-flow intracranial malformations in neonates with high-output cardiac failure. Alternative diagnoses include vein of Galen malformation, dural arteriovenous fistula, and cortical arteriovenous malformation, among other entities.

This article is the first part of a 2-part series on imaging of the inner ear. It will review the normal anatomy, embryology, and intrinsic abnormalities of the otic capsule. The inner ear, comprising the osseous and membranous labyrinths, is a complex anatomic region with structures of high functional relevance. Disorders of the inner ear can consequently lead to disability and can encompass a wide range of etiologies, such as congenital anomalies, trauma, inflammation, and neoplastic conditions, which will be discussed in Part 2. These disorders can manifest as conductive and/or sensorineural hearing loss, as well as other nonspecific clinical manifestations such as vertigo or tinnitus. Given its deep location within the temporal bone and often nonspecific clinical manifestations, imaging is indispensable in the diagnostic work-up and treatment management of the inner ear. An in-depth comprehension of relevant anatomy and basic embryology provides a foundation for understanding the pathophysiologic mechanisms of diseases that can affect the inner ear.Learning Objective: After reading this article, the learner will be able to describe the anatomy and basic embryology of the inner ear, recognize intrinsic abnormalities of the otic capsule, and evaluate the role of imaging in diagnosing and managing inner ear disorders.

Hemophagocytic lymphohistiocytosis (HLH) and Epstein-Barr virus myelitis may manifest with CNS symptoms. Given the similar clinical neurologic presentations of both conditions, differentiating Epstein-Barr virus myelitis from CNS HLH may prove difficult in a patient with a history of HLH. Herein we report a case of Epstein-Barr virus myelitis treated with intrathecal rituximab in a patient with a history of HLH in remission and highlight the role of radiographic imaging in the proper diagnosis.

We present 2 cases of coronavirus disease 2019 (COVID-19)-associated brachial plexus neuropathy. In the setting of the COVID-19 pandemic, many explanations have been proposed for this entity such as positioning-related peripheral nerve injury, microvascular-induced ischemic plexopathy, postinfectious inflammatory neuropathy, or systemic neuropathy. It is often challenging to establish a diagnosis because the potential diagnoses overlap. However, it is important for clinicians to be aware of the potential etiologies of brachial plexus neuropathy in patients with COVID-19.

The spectrum of ocular diseases encountered in the pediatric population is different from that in adults. Recognition of the normal embryologic development and anatomy is crucial to understand various ocular pathologies. Cross-sectional imaging supplements the clinical evaluation in establishing an accurate diagnosis, guiding management and monitoring diseases of the ocular globe. CT is mostly reserved for evaluation of acute processes in the setting of trauma or infection. MR imaging is the technique of choice for most other ocular conditions, given its high soft-tissue resolution. This article highlights the relevant embryologic developmental stages and normal anatomy and provides a review of various pediatric orbital pathologies and their key imaging features.Learning Objective: To recognize the normal embryologic development, anatomy, and key imaging features of common ocular pathologies in the pediatric population to aid the neuroradiologist in promptly detecting and confidently establishing the diagnosis of pediatric ocular disease

In a setting of acute spinal trauma, imaging delineates all osseous and soft-tissue injuries and helps to guide potential surgical intervention. CT is the technique of choice in the setting of acute trauma. However, MR imaging is integral in the assessment of traumatic spinal injury, specifically assessing discoligamentous structures otherwise not seen on CT. We describe the critical imaging parameters of cervical spine injuries in accordance with the Arbeitsgemeinschaft für Osteosynthesefragen (AO) Spine classification system and its impact on neurosurgical management. T2 fat-saturation sagittal and coronal images are valuable in assessing cervical spine ligaments. MR imaging at 3T offers superior resolution than 1.5T. The AO Spine classification for cervical spine injuries is now widely used and is more robust and correlates well with MR imaging. Type A injuries can be managed conservatively. Type B injuries are potentially unstable. B1 osseous injuries alone can be managed conservatively. Anterior or posterior tension band injuries (B2/B3 type) are unstable and are considered for surgical intervention or halo immobilization. Type C injuries have marked ligamentous injury and often require surgery. Identifying key MR imaging findings and using the AO Spine classification system and a reporting template helps bridging the knowledge gap between neuroradiologists and neurosurgeons, in turn influencing patient management.Learning Objectives: To understand the nuances of critical imaging findings of cervical spine injuries in accordance with the AO classification: how to minimize errors in reports using a simple MR imaging reporting template or a checklist; incorporating a universally accepted nomenclature and terminologies to remove bias and ensure consistency in communication with neurosurgical teams; and bridging the knowledge gap between neuroradiologists and neurosurgeons in the management of blunt cervical spinal trauma

Orthognathic surgery, which focuses on improving maxillomandibular alignment, is increasingly used for both functional and cosmetic purposes. Common indications include malocclusion, obstructive sleep apnea, and congenital dentofacial anomalies. Due to the prevalence of in-office imaging performed by oral and maxillofacial surgeons, radiologists are not routinely involved in the perioperative evaluation of patients undergoing orthognathic surgery. An understanding of modern surgical techniques and anatomy is necessary to recognize the normal and abnormal postsurgical findings.Learning Objective: To familiarize radiologists with the role of imaging in the postoperative evaluation after orthognathic surgery and the imaging appearance of both common and rare complications

Primary melanocytic tumors of the central nervous system are rare neoplasms arising from proliferation of multipotent melanin-containing neural crest cells found in the leptomeninges. This review describes the imaging appearance of the entire spectrum of primary melanocytic tumors of the brain and spine in the pediatric population, in correlation with histopathology, clinical features, and prognosis, using sample cases from our institution. These tumors are subclassified by the World Health Organization on the basis of disease distribution and pathologic aggressiveness into the following 4 subtypes: meningeal melanocytoma, meningeal melanoma, meningeal melanocytosis, and meningeal melanomatosis. They can occur in any age group, though the diffuse form of the disease is more prevalent in children and has an association with giant cutaneous melanocytic nevi. Imaging is characterized by hyperattenuation on CT and intrinsic T1 hyperintensity on MR imaging from the presence of melanin and/or hemorrhage. The focal forms usually manifest as dural-based hemorrhagic masses, and the diffuse forms demonstrate dural thickening and enhancement, with or without hydrocephalus. There is a predilection for the medial temporal lobes, posterior fossa, and upper cervical spine. The prognosis is often poor, with a high incidence of malignant transformation of benign disease.Learning Objective: To describe the imaging appearance of the spectrum of primary melanocytic tumors of the brain and spine in the pediatric population and to review the histopathology, clinical, and prognostic data available

Neuroimaging is an essential tool in characterizing calcified intracranial lesions. This article outlines a pictorial review of different calcified lesions of the neuroaxis with discussion of distinguishing radiologic features and clinical and histologic characteristics. There will be an emphasis on the uncommon histologic entity known as calcified pseudoneoplasm of the neuroaxis (CAPNON), a non-neoplastic lesion that is sometimes mistaken for the more common neoplastic and non-neoplastic lesions. It is essential for radiologists to identify key distinguishing imaging features of various calcified intracranial lesions to narrow diagnostic considerations and collaborate with management decisions.Learning Objective: To offer a review of the uncommon histologic entity called calcified pseudoneoplasm of the neuroaxis (CAPNON) and to provide a differential diagnosis and several sample cases of other calcified lesions of the neuroaxis to help the reader differentiate and distinguish CAPNON from more common neoplastic and non-neoplastic lesions