What laboratory tests and initial treatment are recommended for a patient suspected of having encephalitis?

From the Guidelines

For a patient suspected of having encephalitis, immediate laboratory testing should include cerebrospinal fluid (CSF) analysis via lumbar puncture, blood cultures, complete blood count, comprehensive metabolic panel, and specific viral studies including HSV PCR of CSF, as recommended by the Infectious Diseases Society of America 1. The diagnostic approach to patients with encephalitis must include neuroimaging, either MRI or CT, with MRI being the preferred imaging study, though CT may be performed initially to rule out contraindications to lumbar puncture 1. Initial treatment should begin with empiric intravenous acyclovir at 10 mg/kg every 8 hours for adults (20 mg/kg every 8 hours for children) while awaiting test results, as herpes simplex virus is the most common treatable cause with high mortality if untreated 1. Broad-spectrum antibiotics (such as ceftriaxone 2g IV every 12 hours and vancomycin 15-20 mg/kg IV every 8-12 hours) should be added if bacterial meningitis cannot be excluded 1. Some key points to consider in the diagnosis and management of encephalitis include:

• The importance of early recognition and treatment, as delayed therapy can lead to irreversible neuronal damage and high mortality rates 1
• The need for a thorough diagnostic evaluation, including neuroimaging, serologic testing, and CSF analysis, to identify the underlying cause of encephalitis 1
• The use of standardized case history forms and laboratory data to facilitate collaboration and advance diagnosis and management of encephalitis 1
• The consideration of specific geographic regions and prior travel history/place of residence when selecting tests for fungal, arbovirus, and tick-borne diseases 1 Supportive care including seizure management with benzodiazepines and antiepileptics, intracranial pressure monitoring if elevated, and respiratory support as needed are essential components of treatment. Early treatment significantly improves outcomes, as neuronal damage from viral encephalitis can be irreversible if therapy is delayed, with HSV encephalitis carrying a mortality rate of 70% without treatment versus 20-30% with prompt acyclovir administration 1.

From the Research

Laboratory Tests for Encephalitis

• Cerebrospinal fluid (CSF) analysis for protein and glucose levels, cellular analysis, and identification of the pathogen by polymerase chain reaction (PCR) amplification 2, 3
• Serology for identification of the pathogen 2, 3
• Neuroimaging, preferably by magnetic resonance imaging (MRI) 2, 3, 4
• Lumbar puncture, which can follow neuroimaging when immediately available, but should be delayed only in the presence of strict contraindications 2, 3
• Brain biopsy, which should be reserved only for unusual and diagnostically difficult cases 2, 3

Initial Treatment for Encephalitis

• Supportive therapy as an important basis of management 2, 3
• Specific, evidence-based, antiviral therapy, such as acyclovir for herpes encephalitis 2, 3, 4
• Acyclovir may also be effective for varicella-zoster virus encephalitis, ganciclovir and foscarnet for cytomegalovirus encephalitis, and pleconaril for enterovirus encephalitis 2, 3
• Corticosteroids as an adjunct treatment for acute viral encephalitis are not generally considered to be effective, and their use is controversial 2, 3
• Surgical decompression is indicated for impending uncal herniation or increased intracranial pressure refractory to medical management 2, 3

Hospitalization and Monitoring

• All encephalitis cases should be hospitalized with access to intensive care units 2, 3, 5
• Patients should be monitored for complications and sequelae, particularly in patients with eastern equine or HSV encephalitis 5