From the Guidelines
The initial approach to a comprehensive encephalitis workup should begin with immediate neuroimaging (preferably MRI with contrast) and lumbar puncture for CSF analysis, alongside empiric antimicrobial therapy while awaiting results, as recommended by the most recent guidelines 1. This approach is crucial in identifying the underlying cause of encephalitis, which can be viral, bacterial, fungal, parasitic, or autoimmune in nature. The use of MRI with contrast is preferred over CT scans due to its superior ability to demonstrate CNS abnormalities, as noted in the 2013 consensus statement by the International Encephalitis Consortium 1.
Key Components of the Workup
- Empiric treatment typically includes acyclovir 10 mg/kg IV every 8 hours for HSV coverage, plus broad-spectrum antibiotics such as ceftriaxone 2g IV every 12 hours and vancomycin 15-20 mg/kg IV every 8-12 hours if bacterial meningitis cannot be excluded.
- CSF analysis should include cell count, protein, glucose, Gram stain, culture, HSV PCR, and other pathogen-specific PCR tests based on epidemiology.
- Blood tests should include complete blood count, comprehensive metabolic panel, blood cultures, HIV testing, and serology for relevant infectious agents.
- EEG should be performed to evaluate for subclinical seizures, particularly in patients with altered mental status.
- Additional testing may include autoimmune panels (anti-NMDA receptor antibodies, anti-VGKC antibodies) when infectious causes are negative, as suggested by the 2021 recommendations for autoimmune encephalitis 1.
Importance of Prompt Diagnosis and Treatment
Delays in treatment can significantly increase morbidity and mortality, particularly for treatable causes like HSV encephalitis, highlighting the need for a comprehensive and timely approach to the diagnosis and management of encephalitis, as emphasized in the 2008 guidelines by the Infectious Diseases Society of America 1.
Considerations for Autoimmune Encephalitis
In cases where autoimmune encephalitis is suspected, the use of corticosteroids alone or combined with other agents (intravenous IG or plasmapheresis) as first-line therapy is recommended, with rituximab being a preferred second-line agent, as indicated by the 2021 study on autoimmune encephalitis 1.
By following this comprehensive approach, clinicians can ensure that patients with encephalitis receive timely and appropriate treatment, which is critical for improving outcomes and reducing morbidity and mortality.
From the Research
Comprehensive Encephalitis Workup
The initial approach to a comprehensive encephalitis workup involves several key steps:
- Medical history and examination to identify potential causes and risk factors 2
- Cerebrospinal fluid (CSF) analysis for protein and glucose levels, cellular analysis, and identification of the pathogen by polymerase chain reaction amplification and serology 2
- Neuroimaging, preferably by MRI, to visualize the brain and detect any abnormalities 2, 3, 4
- Electroencephalogram (EEG) to assess brain activity and detect any seizures or abnormal patterns 3, 4
Diagnostic Considerations
- Brain biopsy may be reserved for unusual and diagnostically difficult cases, but it is not typically the first line of diagnosis 2, 5
- Lumbar puncture (LP) should be performed promptly, unless there are concerns about increased intracranial pressure or other contraindications 2
- CSF analysis should include testing for herpes simplex virus (HSV) and other potential pathogens 2, 3, 4, 5, 6
Treatment Considerations
- Antiviral therapy, such as acyclovir, should be initiated promptly in cases of suspected or confirmed herpes simplex encephalitis 2, 3, 4, 5, 6
- Corticosteroids may be considered as an adjunct treatment, but their use is controversial and should be individualized 2
- Surgical decompression may be necessary in cases of increased intracranial pressure or impending herniation 2