Aseptic meningitis

• Signs and symptoms of meningeal inflammation with negative routine bacterial culture of CSF

Differential Diagnosis

• See also causes of CSF pleocytosis
• Infectious
  • Viral
    • Enterovirus EV-B species (includes Group B coxsackieviruses and echoviruses) are the most common cause of aseptic meningitis in both children and adults
      • CV-B2 to CV-B5, E-6, E-6, E-9, E-11, E-13, E-16, E-18, E-30, and E-33
    • Parechovirus, especially in very young children and immunocompromised hosts
    • Herpes simplex virus (especially HSV-2, as primary infection)
    • Varicella
    • Mumps (encephalitis), measles (acute encephalitis)
    • Arboviruses
    • Lymphocytic choriomeningitis virus (LCMV)
    • Acute HIV
    • EBV, influenza, Colorado tick virus, rabies
  • Bacterial
    • Leptospirosis
    • Lyme disease
    • Rickettsia (before onset of fever)
    • Other causes of bacterial meningitis after antibiotics
  • Mycobacterial
  • Fungal
• Non-infectious
  • Autoimmune or inflammatory
    • Systemic lupus erythematosus
    • Behçet disease
    • Sarcoidosis
    • Vogt-Koyanagi-Harada syndrome
  • Drug-induced meningitis
    • Antimicrobials: TMP-SMX, amoxicillin, isoniazid
    • IVIg
    • Azathioprine
    • Ibuprofen and other NSAIDs
    • Allopurinol
  • Malignancy
    • Leukemia
    • Lymphoma
    • Metastatic carcinoma or adenocarcinoma
  • Other
    • Epidermoid cyst
    • Post-vaccination

Investigations

• Enterovirus
  • Usually positive PCR of CSF
  • Can look for enterovirus in stool, nasopharyngeal, and throat, as well as conjunctiva if there is conjunctivitis
  • Persists in stool for several weeks, but less specific
  • NP preferred over throat
• Parechovirus PCR if very young child or immunocompromised
• West Nile virus IgM/IgG/PCR from CSF and blood
• Syphilis screening EIA
• HIV screen