E2422. A Neuroimaging Review of Pediatric Encephalitides
  1. Jennifer Huang; Vanderbilt University
  2. Asha Sarma; Vanderbilt University
  3. Sumit Pruthi; Vanderbilt University
Pediatric encephalitis is an uncommon but potentially devastating condition that is due to inflammation of the brain parenchyma. There are over 100 etiologies associated with encephalitis, although in most cases, the cause remains unknown. Furthermore, the variable clinical presentation makes it difficult to distinguish from other pediatric pathologies causing neurologic dysfunction. This exhibit is an organized review to discuss the common etiologies of pediatric encephalitis, as well as provide examples of some of the more uncommonly encountered causes, as grouped below.

Educational Goals / Teaching Points
This exhibit provides an organized review of common etiologies of pediatric encephalitis. In addition, selected uncommonly encountered entities are discussed. Entities with distinctive neuroimaging and clinical/biochemical features will be emphasized. Recent scientific advancements in the understanding of these disorders will also be applied.

Key Anatomic/Physiologic Issues and Imaging Findings/Techniques
Pediatric encephalitides can be categorized into two broad groups: infectious and non-infectious. Selected examples of entities included in each category are as follows: 1. Infectious: a. viral (e.g., enterovirus, varicella, herpes, Epstein-Barr, arbovirus); b. bacterial (e.g., mycoplasma, rickettsia); and c. fungi and parasites. 2. Noninfectious: a. Immune-cell mediated (e.g., ADEM); b. antibody-mediated (e.g., anti-NMDA-receptor, Hashimoto encephalitis); and c. other: Rasmussen encephalitis. Neuroimaging is often indicated to help identify the etiology, exclude mimicking conditions, and assess for potential complications. MRI is the gold standard for imaging evaluation of suspected central nervous system infection. Advanced modalities such as MR angiography, arterial spin labeling, vessel wall imaging, and MR spectroscopy may be useful in selected cases.

Given substantial clinical and imaging overlap among pediatric encephalitides, superficial resemblance among disorders can lead to confusion. This review aims to help radiologists identify salient key features that can add value in diagnosing these disorders.