Cerebrospinal Fluid Analysis in Aseptic Meningitis

Characteristics of CSF Pleocytosis

• In viral meningitis, especially enteroviral disease, patients are unlikely to have a total CSF white cell count exceeding 2000 cells/mm³ 1

CSF Biochemistry in Aseptic vs. Bacterial Meningitis

• CSF protein is typically only mildly raised in viral meningitis compared to markedly elevated levels in bacterial meningitis 2
• CSF glucose is usually normal or only slightly decreased in viral meningitis, whereas it's significantly reduced in bacterial meningitis 2
• CSF/plasma glucose ratio remains normal or slightly low in viral meningitis but is very low in bacterial meningitis 2

Special Considerations

• In patients with enterovirus infection, approximately 50% will have CSF pleocytosis 3
• In Human Monocytic Ehrlichiosis (HME), a lymphocytic pleocytosis can be observed in the CSF in approximately 50% of patients who undergo lumbar puncture, with neutrophilic pleocytosis sometimes seen early in the course of illness 4
• A lumbar puncture may still be diagnostically useful even after several days of illness in cases of suspected meningitis 1