Diagnostic algorithm for initial evaluation of encephalitis in children is proposed with a consensus statement from the International Encephalitis Consortium, a committee begun in 2010 to serve as a practical aid to clinicians evaluating patients with suspected encephalitis. Encephalitis is defined as inflammation of the brain parenchyma associated with neurologic dysfunction. Major diagnostic criterion is an altered mental status lasting >24 hours. Minor criteria include fever, seizures, focal neurologic findings, CSF WBC count >5/cubic mm, MRI parenchymal lesion, or EEG abnormality indicative of encephalitis (>3 required for probable or confirmed encephalitis).

Routine studies proposed include CSF, serum, imaging (MRI preferred), EEG, throat sample for Mycoplasma pneumoniae PCR, and throat and stool specimens for enterovirus PCR. Specific signs and symptoms of encephalitis include abnormal behavior, psychotic features, seizures or movement disorder indicating need for NMDAR antibody test in serum and CSF; vesicular rash indicating VZV PCR from CSF; respiratory symptoms indicating Mycoplasma pneumoniae PCR in CSF; and limbic symptoms indicating autoimmune limbic encephalitis testing HHV6/7 PCR (CSF). [1]

COMMENT. The definition proposed is chosen to capture both encephalitis and encephalopathy. Encephalopathy is a clinical state of altered mental status, manifesting as confusion, disorientation, behavioral changes, or other cognitive impairments, with or without inflammation of brain tissue. Encephalitis is characterized by brain inflammation resulting from direct infection of the brain parenchyma (e.g. Bartonella or influenza), a post-infectious process as in ADEM or a noninfectious condition such as NMDAR encephalitis. The definition covers infectious and noninfectious encephalitis and encephalopathy of presumed infectious etiology. Specific etiologies are identified in < 50% of cases.

Proteomes in plasma and CSF of children with cerebral malaria were found to differ from those with acute bacterial meningitis and nonspecific encephalopathies. Pathogenic states in children with impaired consciousness in malaria endemic areas could be reflected by changes in protein biomarkers in both plasma and CSF. [2]