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Abstract:
Viral meningitis is part of the aseptic meningitis syndrome but must be distinguished from bacterial meningitis on the basis of a careful examination of the CSF and sound clinical judgment. Enteroviruses probably account for the bulk of cases of aseptic meningitis that occur in the United States and which are reported to the Centers for Disease Control each year. The seasonal pattern in the incidence of aseptic meningitis is largely due to the seasonal variation of enteroviral infections. Early on, the CSF in patients with viral meningitis frequently contains a predominance of polymorphonuclear leukocytes and may even have a low glucose level. The presence of neutrophils in the initial CSF sample is especially common in patients with enteroviral infections. A CSF glucose level lower than 50 per cent of a simultaneously drawn blood glucose determination is not uncommon in patients with viral meningitis due to mumps, LCM, and herpes simplex. In a patient with a predominance of polymorphonuclear leukocytes in the initial CSF specimen and in whom a viral infection is suspected, antibiotics may be withheld if a spinal tap is repeated within 12 hours. A shift from polymorphonuclear leukocytes to mononuclear cells makes viral meningitis the likely diagnosis. Both herpes simplex and varicella-zoster may infect the meninges by means of spread from cervical and dorsal root ganglia in a retrograde fashion much the way they spread in an antegrade fashion to the skin. HSV-2 is more likely to cause the clinical syndrome of viral meningitis, while HSV-1 is more likely to cause a meningoencephalitis with serious brain dysfunction. The identification of a specific viral agent in body fluids, especially the CSF, in a patient with aseptic meningitis is of more than academic interest, since it can shorten duration of hospital stay and eliminate unnecessary antimicrobial therapy. The diagnosis of enteroviral infections depends upon the isolation of a virus from CSF, stool, or throat plus a fourfold antibody response in the serum to the viral isolate. The 60-odd serotypes of enterovirus, each with different antigenic determinants, preclude serologic testing alone as a useful diagnostic test to identify the patient infected with coxsackievirus or echovirus. For infections, due to herpes simplex, varicella-zoster, LCM, and arboviruses, a serologic test alone can be useful.(ABSTRACT TRUNCATED AT 400 WORDS)
Insights
Differentiating viral meningitis from bacterial meningitis relies on cerebrospinal fluid (CSF) analysis and clinical judgment. Early CSF findings like polymorphonuclear leukocytes and low glucose can indicate viral meningitis, guiding treatment decisions.
Area of Science:
- Neurology
- Infectious Diseases
- Virology
Background:
- Viral meningitis is a form of aseptic meningitis syndrome requiring differentiation from bacterial meningitis.
- Enteroviruses are the most common cause of aseptic meningitis in the United States, exhibiting seasonal incidence patterns.
- Cerebrospinal fluid (CSF) analysis is crucial for diagnosis, with initial findings potentially including polymorphonuclear leukocytes and low glucose levels.
Purpose of the Study:
- To highlight the importance of distinguishing viral meningitis from bacterial meningitis through CSF examination and clinical assessment.
- To discuss the diagnostic criteria and etiological agents of viral meningitis, particularly enteroviral infections.
- To emphasize the clinical significance of identifying specific viral pathogens for optimizing patient management and treatment.
Main Methods:
- Analysis of cerebrospinal fluid (CSF) characteristics, including cell counts (polymorphonuclear leukocytes vs. mononuclear cells) and glucose levels.
- Clinical judgment based on patient presentation and examination findings.
- Diagnostic approaches for specific viral agents such as enteroviruses, herpes simplex virus (HSV), varicella-zoster virus, and arboviruses, including viral isolation and serologic testing.
Main Results:
- Initial CSF in viral meningitis may show polymorphonuclear leukocytes and low glucose, especially in enteroviral infections.
- A shift from neutrophils to mononuclear cells in CSF suggests viral meningitis.
- Herpes simplex virus type 2 (HSV-2) is associated with meningitis, while HSV-1 is linked to meningoencephalitis. Serologic tests are useful for diagnosing infections caused by herpes simplex, varicella-zoster, LCM, and arboviruses.
Conclusions:
- Accurate diagnosis of viral meningitis is essential to avoid unnecessary antimicrobial therapy and shorten hospital stays.
- Understanding CSF profiles and employing appropriate diagnostic tests aids in identifying the causative viral agent.
- Specific viral diagnoses, like enteroviral infections, rely on viral isolation and antibody response, while other viral infections can be diagnosed serologically.