Brain Imaging
Imaging Patterns of Toxic and Metabolic Brain Disorders
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Arthur M. de Oliveira , Matheus V. Paulino, Ana P. F. Vieira, Alexander M. McKinney, Antonio J. da Rocha, Germana T. dos Santos, Abstract
Toxic and metabolic brain disorders are relatively uncommon diseases that affect the central nervous system, but they are important to recognize as they can lead to catastrophic outcomes if not rapidly and properly managed. Imaging plays a key role in determining the most probable diagnosis, pointing to the next steps of investigation, and providing prognostic information. The majority of cases demonstrate bilateral and symmetric involvement of structures at imaging, affecting the deep gray nuclei, cortical gray matter, and/or periventricular white matter, and some cases show specific imaging manifestations. When an appropriate clinical situation suggests exogenous or endogenous toxic effects, the associated imaging pattern usually indicates a restricted group of diagnostic possibilities. Nonetheless, toxic and metabolic brain disorders in the literature are usually approached in the literature by starting with common causal agents and then reaching imaging abnormalities, frequently mixing many different possible manifestations. Conversely, this article proposes a systematic approach to address this group of diseases based on the most important imaging patterns encountered in clinical practice. Each pattern is suggestive of a most likely differential diagnosis, which more closely resembles real-world scenarios faced by radiologists. Basic pathophysiologic concepts regarding cerebral edemas and their relation to imaging are introduced—an important topic for overall understanding. The most important imaging patterns are presented, and the main differential diagnosis for each pattern is discussed.
Online supplemental material is available for this article.
©RSNA, 2019
SA-CME LEARNING OBJECTIVES
After completing this journal-based SA-CME activity, participants will be able to:
■ Identify the imaging features of some of the most prevalent CNS toxic and metabolic disorders.
■ Describe imaging findings that are highly specific for the diagnosis of particular toxic and metabolic brain disorders.
■ Recognize the most important types of cerebral edema and their imaging characteristics.
Introduction
This article addresses some of the most challenging diagnostic issues in neuroimaging. Toxic and metabolic brain disorders manifest secondary to derangements of a well-balanced environment encompassing metabolic substrates, neurotransmitters, electrolytes, physiologic pH levels, and blood flow, either by endogenous malfunctions or exogenous toxic effects. Patients with these disorders often present to the emergency department and are diagnosed with global cerebral dysfunction presenting as acute confusional state and delirium, but commonly they are also critically ill inpatients. These cases often demand a fast and effective management approach because they may result in permanent structural brain damage. Imaging plays a key role in these cases, as imaging findings can be used to diagnose the condition or narrow the differential diagnosis (1).
In addition to providing a final diagnosis, imaging can provide prognostic information. Extensive lesions involving gray matter are often related to poor prognosis and outcomes, while lesions restricted to white matter, sparing cortical and deep gray matter, can point to a reversible cause.
https://pubs.rsna.org/doi/10.1148/rg.2019190016
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