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Clinical Differences Between Encephalitis and Meningitis

Meningitis and encephalitis are serious conditions that require prompt medical attention to avert adverse outcomes. Bacterial meningitis can be deadly for otherwise healthy people or may cause stroke, hearing loss, or brain damage.1 Encephalitis is often mild, but severe illness can leave patients with long-term after-effects including acquired brain injury (ABI).2

Meningitis is an inflammation of the membranes, called meninges, that surround the brain and spinal cord. Encephalitis is inflammation of the brain itself. Both encephalitis and meningitis can be caused by infections or non-infectious causes. In order to appropriately treat encephalitis or meningitis, clinicians must determine if the cause is infectious or non-infectious—and if it's infectious, whether it's bacterial, viral, or fungal (yeast).

Because encephalitis and meningitis each affect different tissues, they can cause distinct symptoms. Below are some of the similarities and differences between encephalitis symptoms and meningitis symptoms.

Potential Meningitis or Encephalitis Symptoms1

Viral, Bacterial, or Yeast?

Appropriate treatment for meningitis depends on determining whether the cause is bacterial, viral, or yeast. Making this determination quickly is crucial, as bacterial meningitis can prove fatal within 24 to 48 hours.3 Viral meningitis often resolves on its own, without treatment; however, any kind of meningitis can be serious and those experiencing symptoms should seek medical attention promptly.4

Encephalitis is most commonly caused by a virus, but in rare cases it can also be caused by bacteria or yeast. Viral encephalitis is frequently caused by enteroviruses and herpes simplex viruses, among others.1 About half of untreated herpes simplex-caused encephalitis cases result in death.1

Challenges of Traditional Testing

The symptoms of meningitis and encephalitis are non-specific, meaning they are common among a variety of conditions and infections. When patients present with symptoms that could indicate meningitis or encephalitis, clinicians conduct physician examinations and order various diagnostic tests to home in on what's causing the illness.

Lab screenings of blood, urine, or other bodily secretions can help determine if infection is present.1 Cerebrospinal fluid can be tested for the presence of pathogens and to measure indicators of infection such as white blood cells, protein, glucose, and antibodies.1 Other testing may include CT scans and MRIs to look at images of the brain and surrounding tissues, or EEGs to monitor brain waves for signature patterns caused by viral infections.

If infection is identified, determining the source of infection presents another challenge, as several pathogens can cause similar symptoms. Traditional cerebrospinal fluid culture can take days to return results. Meanwhile, patients may be treated with empiric antimicrobials that may be unnecessary or overly broad.

The Syndromic Approach to Meningitis/Encephalitis Testing

Syndromic testing combines a broad grouping of probable targets into one quick test to maximize the chance of getting an actionable answer in a clinically relevant timeframe. The syndromic BIOFIRE® FILMARRAY® Meningitis/Encephalitis (ME) Panel identifies 14 of the most common infectious causes of meningitis and encephalitis, including bacteria, viruses, and yeast. The BIOFIRE ME Panel returns results in about an hour, helping to support timely, targeted treatment.

With results in about an hour—instead of days—the BIOFIRE ME Panel has been shown to shorten time to diagnosis, increase diagnostic yield, reduce antimicrobial duration, and shorten hospital stays.5-10

References

  1. Meningitis and Encephalitis Fact Sheet. Accessed 17 Jan 2023. Retrieved from: https://www.ninds.nih.gov/meningitis-and-encephalitis-fact-sheet#3083_5
  2. Encephalitis Society. After-Effects of Encephalitis. Accessed 17 Jan 2023. Retrieved from: https://www.encephalitis.info/Pages/Category/after-effects-of-encephalitis
  3. Confederation of Meningitis Organisations Fact Sheet. comomeningitis.org/facts. 2020.
  4. Viral Meningitis. Accessed 17 Jan 2023. Retrieved from: https://www.cdc.gov/meningitis/viral.html#print
  5. O'Brien M, et al. The Pediatric Infectious Disease Journal 2018;37:868-71.
  6. Cailleaux M, et al. European Journal of Clinical Microbiology & Infectious Diseases 2019;39(2):293-297.
  7. Evans M, et al. Diagnostic Microbiology and Infectious Disease 2020;96(2):114935.
  8. Posnakoglou L, et al. European Journal of Clinical Microbiology & Infectious Diseases Jul 2020.
  9. Moffa M, et al. Antibiotics (Basel) 2020;9(6):282.
  10. Hagen A, BMC Pediatrics, 20(56).

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