Pediatric emergency medicine trisk 2272 2272

Encephalitis is an inflammation of the brain that can occur with or without associated meningeal irritation; the former is termed meningoencephalitis, but the terms will be used interchangeably in this section The clinical manifestations can overlap with those of meningitis The etiologies most commonly associated with encephalitis are listed in e-Table 94.2 ; however, an etiology is found in only a small fraction of children and adults with encephalitis In circumstances where etiologies are found, almost 70% are viral (most commonly enterovirus, followed by HSV and Epstein–Barr virus [EBV]) and approximately 20% are bacterial In the last two decades, it has been recognized that several arboviruses endemic in the United States can cause encephalitis These viruses, which include West Nile, St Louis, La Crosse, and the equine encephalitides, are termed arbo viruses because they are ar thropod-bo rne viruses, not because they share phylogenetic characteristics The clinical manifestations include altered consciousness or behavioral changes, seizures, hemiparesis, or ataxia, often with nausea and vomiting Fever is not uniformly present Postinfectious cases can have associated demyelination in the absence of acute signs of infection; most cases of brainstem encephalitis are postinfectious The differential diagnosis of encephalitis includes ingestion, metabolic disorders, structural lesions (masses, bleeds, emboli), acute demyelinating encephalomyelitis (ADEM), and autoimmune encephalitis (NMDAR) One diagnostic approach to the child with suspected encephalitis is listed in Table 94.10 , realizing that repeated history taking may be necessary to elucidate all exposures a child may have had Children with encephalitis should be started on acyclovir (20 mg/kg every hours) pending HSV PCR, as this is one of the few treatable causes of encephalitis If a CSF pleocytosis exists, empiric initiation of parenteral antibiotics (e.g., vancomycin [15 mg/kg every hours] and cefotaxime [75 mg/kg every hours; maximum: g/dose]) is reasonable pending bacterial culture results Consideration should be given to admission of these patients to intensive care unit settings for closer monitoring given concerns for changes in the ability to protect the airway, increased intracranial pressure, or electrolyte imbalances Standard precautions are recommended for most forms of encephalitis