, et al
Infectious and autoimmune causes of encephalitis in children
):e20192543; doi:

Investigators from several Texas institutions conducted a retrospective cohort study to assess the etiology and characteristics of pediatric patients diagnosed with encephalitis. Children were eligible if they had an ICD-9 or ICD-10 code associated with encephalitis or meningoencephalitis from an admission at Texas Children’s Hospital from 2010–2017 and were >90 days old and <18 years old. Investigators reviewed the medical records of eligible children to identify cases of encephalitis using the 2013 International Encephalitis Consortium definition for encephalitis, which required altered mental status lasting ≥24 hours with no other explainable cause and ≥2 of the following: fever ≥38°C within 3 days of presentation, new onset seizures, new onset of focal neurologic findings, cerebrospinal fluid (CSF) white blood cell count of ≥5/mm3, new onset neuroimaging abnormality, or EEG abnormality. Data on demographics, lab, clinical characteristics, and season of admission of identified encephalitis cases were abstracted from the medical record.

Cases were categorized as having an identified or unknown etiology. Identified etiologies included infectious etiologies, which were further categorized as viral, bacterial, or other, and noninfectious etiologies, which included autoimmune or immune-mediated etiologies. To meet criteria for autoimmune encephalitis, cases needed to have altered mental status or neuropsychiatric deficits and ≥1 objective central nervous system abnormality. Cases also were considered to have autoimmune encephalitis if the CSF antibody test was present in an abnormal range in the absence of any other identified case of encephalitis.

There were 231 identified cases of encephalitis during the study period, with 58% (N=133) having an identified etiology. Among cases with identified etiologies, most (N=73) had infectious etiologies. The predominant infectious etiology was viral (N=51), with the most common viral etiologies being herpesvirus (N=20) and arbovirus (N=13, with West Nile virus causing 12 of these cases). The most common bacterial etiology was Bartonella henselae (N=7). Among the 60 cases of noninfectious etiology, the most frequently identified cause was anti-N-methyl-D-aspartate receptor (NMDAR) encephalitis (N=31). Infectious (vs autoimmune) causes of encephalitis were significantly more common in males and those who were immunocompromised. There were no observed associations between etiologies of encephalitis and season of admission.

The investigators conclude that arbovirus, Bartonella, and NMDAR testing should be considered in the etiologic diagnosis of encephalitis in children.

Dr Brady has disclosed no financial relationship relevant to this commentary. This commentary does not contain a discussion of an unapproved/investigative use of a commercial product/device.

Encephalitis is a rare, but serious, neurologic condition that often requires ICU management. Similar to previous investigators,2,3  the authors identified an etiology in about half of the 231 cases. Identifying an etiology may allow initiation of effective therapy. Herpes simplex virus (HSV) encephalitis is treated with IV acyclovir and, therefore, polymerase chain...

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