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Autoimmune Encephalitis

Introduction Autoimmune encephalitis refers to a recently recognized group of immune-mediated disorders that involve the central nervous system (CNS). These conditions, which overlap in their clinical manifestations and imaging findings, are ultimately tied to specific antibodies ( Fig. 11.1 ). The clinical and imaging features depend on the particular CNS structure(s) targeted by the antibodies. In addition to limbic encephalitis, which may be the most common…

Acute Disseminated Encephalomyelitis

Introduction Acute disseminated encephalomyelitis (ADEM) is a rare, usually monophasic, immunologically mediated inflammatory disease of the central nervous system (CNS) with characteristic polyfocal involvement of the neuroaxis on imaging. It may occur at any age but is most commonly seen in the pediatric population, with the mean age at presentation between 5 and 8 years. It has a reported incidence of 0.007 to 0.64 per 100,000…

Neurocysticercosis

Introduction Cysticercosis is a parasitic infection caused by the larval stage of the tapeworm Taenia solium . The central nervous system (CNS), eyes, and muscles are the most commonly involved sites. Neurocysticercosis (NCC) is considered the most common parasitic infection of the CNS and is a major cause of acquired epilepsy in some areas of the world. It is reported to affect 50 million people, with…

Toxoplasmosis

Introduction Central nervous system (CNS) toxoplasmosis is an opportunistic infection caused by the intracellular protozoan parasite Toxoplasma gondii . This parasite may be acquired in utero or through the ingestion of infected meat or cat feces, as cats are its definitive host. While T. gondii infects a large portion of the population, it uncommonly causes significant disease in immunocompetent individuals. T. gondii typically causes disease in…

Herpes Simplex Encephalitis

Introduction Herpes simplex encephalitis (HSE) is the most common cause of fatal sporadic encephalitis worldwide. In adults and older children, most cases of HSE are caused by the herpes simplex virus 1 (HSV-1) virus. Patients initially present with nonspecific neurologic signs, including altered mental status, focal cranial nerve defects, hemiparesis, dysphagia, aphasia, ataxia, and seizures, usually with accompanying fevers. Symptoms of encephalopathy then progress with devastating…

Central Pontine Myelinolysis

Introduction Central pontine myelinolysis (CPM) was originally described by . He first detailed the entity in a group of malnourished and alcoholic patients. Further studies and advancement in medicine have shown that CPM most commonly results from the rapid correction of serum sodium in hyponatremic patients. The pathophysiology of CPM is currently not fully understood. However, it has been shown that CPM results from the physiologic…

Wernicke Encephalopathy

Introduction Wernicke encephalopathy (WE) was first described in 1881 by Carl Wernicke as a “superior acute hemorrhagic polioencephalitis.” WE is now recognized as a complication of thiamine (vitamin B1) deficiency and results in the following clinical triad: mental confusion, gait ataxia, and ocular dysfunction. Diagnosing WE is straightforward when a known alcoholic demonstrates all of these symptoms. Unfortunately, this occurs in a minority of patients. One…

Cerebral Amyloid Angiopathy

Introduction Cerebral amyloid angiopathy (CAA) is a microangiopathy defined by progressive deposition of beta amyloid (Aβ) in the walls of distal cortical and leptomeningeal vessels. The resulting small vessel damage can result in hemorrhage, infarction, and/or chronic hypoperfusion, the sequela of which produce a spectrum of characteristic neuroimaging findings. Although both hereditary and sporadic forms exist, in this chapter, we will focus on sporadic CAA, which…

Posterior Reversible Encephalopathy Syndrome

Introduction Posterior reversible encephalopathy syndrome (PRES) refers to a potentially reversible neurotoxic state occurring in association with vasogenic cerebral edema. Although the reported age range varies between 4 and 90 years, most affected patients are in their fourth or fifth decade of life. There is a female predominance, partly attributed to the underlying etiology. Clinically, PRES can present with a constellation of symptoms, with altered mental…

Subdural Hemorrhage and Posttraumatic Hygroma

Introduction The accurate age determination of a subdural hemorrhage is one of the most common and basic assessments in the setting of head trauma. On computed tomography (CT), the classic descriptions of blood products within the subdural space relate to density changes which evolve over time. These changes reflect the evolution from acute blood to clot formation, clot retraction, clot lysis, and eventual resorption. Based on…

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Brain Parenchymal Hematoma Evolution

Introduction Magnetic resonance imaging (MRI) can differentiate between acute, subacute, and chronic hemorrhage because of its sensitivity and specificity to hemoglobin degradation products. Therefore the imaging interpreter is, with proper knowledge, able to estimate the age of a brain parenchymal hematoma. The blood products in a hematoma evolve through a predictable variation in hemoglobin oxygenation states and hemoglobin byproducts. This predictable pattern of hematoma evolution over…

Anatomy and Degenerative Diseases of the Spine

Spinal Parlance This chapter begins with a brief review of the anatomy of the spine. Imaging techniques are then discussed, followed by the normal imaging appearance of the spine on magnetic resonance (MR) imaging and computed tomography (CT). We then consider degenerative diseases of the spine. These common diseases may manifest as localized back pain, radiculopathy (pain radiating in a spinal root distribution), or myelopathy (signs…

Extramucosal Diseases of the Head and Neck

As opposed to the mucosal diseases of the head and neck, in which the differential diagnosis usually revolves around squamous cell carcinoma 90% of the time, the extramucosal space allows the radiologist to exercise finely honed skills in forming a differential diagnosis. Rumination, differentiation, pontification and “clinical correlation” may follow—and not just in this chapter. The reader should understand that more comprehensive multivolumed dry texts dealing…

Mucosal and Nodal Disease of the Head and Neck

The approach to this chapter on mucosal disease is divided along disease categories combining all regions except for the discussion of malignant masses. Because the basis for discussing cancers with clinicians is rooted in the TNM staging of the American Joint Commission on Cancer, which is itself subdivided by anatomic location, the chapter will analyze squamous cell carcinoma based on sites of origin. An old adage…

Sinonasal Disease

To appreciate the pathogenesis of sinusitis, you must understand the normal anatomic pathways of mucociliary clearance in the paranasal sinuses ( Fig. 12-1 ). The cilia within the maxillary sinus propel the mucous stream in a starlike pattern from the floor of the maxillary sinus toward the ostium situated superomedially. In approximately 30% of patients, a second accessory ostium to the maxillary sinus is present inferior…

Temporal Bone

The detailed bony anatomy of the vestibulocochlear structures of the temporal bone makes computed tomography (CT) the primary method of evaluating the erosive and inflammatory lesions of the temporal bone. Magnetic resonance imaging (MRI) also has an important role in the evaluation of temporal bone pathology, particularly when evaluating vascular and neoplastic processes affecting this region. A good understanding of the anatomy of the temporal bone…

Sella and Central Skull Base

Anatomy True story: in order to understand imaging of the skull base you are going to have to appreciate the normal anatomy first. We define the skull base as the region from the upper surface of the ethmoid bone and orbital plate of the frontal bone to the occipital bone. Central to the skull base is the sphenoid bone—the main attraction, so to speak. The bone…

Orbit

Time to play with the eye-ball—at first base, anatomy. The orbit is a cone-shaped structure made up of seven bones ( Fig. 9-1 ). The roof is formed by the orbital plate of the frontal bone anteriorly and the lesser wing of the sphenoid bone posteriorly. The lateral wall of the orbit is composed of the zygomatic bone anteriorly and the greater wing of the sphenoid…

Congenital Anomalies of the Central Nervous System

Timing of Formation of Congenital Lesions If you think your ex utero life is complicated, wait till you see what goes on in utero! Understanding development of the central nervous system (CNS) aids in understanding congenital brain and spine anomalies and coexistence of multiple anomalies. Although there is some overlap, to put things simply, the CNS goes through six major developmental events that include (1) primary…