Chronic meningitis

Differential Diagnosis

• Fungal infections
  • Cryptococcus
  • Coccidioides
  • Histoplasma
  • Candida
  • Sporothrix (rare)
  • Blastomyces (rare)
  • Other rare molds: Scedosporium, Aspergillus, Cladophialophora, and other dematiaceous molds
• Bacterial infections
  • Mycobacterium tuberculosis
  • Treponema pallidum
  • Borrelia burgdorferi
  • Tropheryma whipplei
  • Actinomyces (parameningeal, rare)
  • Nocardia (with brain abscess)
  • Brucella (rare)
• Viral infections
  • Echovirus (meningoencephalitis)
• Parasitic infections
  • Acanthamoeba
  • Balamuthia
  • Taenia solium
  • Angiostrongylus cantonensis
• Other causes
  • Post-neurosurgical causes: infected CSF shunt, infected prosthetic material
  • Tumours: diffuse gliomatosis, metastatic meningeal malignancies including lymphomatous meningitis
  • Others: sarcoidosis, Vogt-Koyanagi-Harada syndrome, Behçet syndrome, IgG4-related hypertrophic pachymeningitis

Investigations

• CSF tests:
  • Glucose, protein, cell count and differential (including eosinophils)
  • India ink on centrifuged sediment
  • Fungal culture of 3-5 mL of CSF
  • Cytopathology for malignant cells, including PCR or flow cytometry for monoclonal B cells
  • Periodic acid-Schiff stain for Whipple disease
  • VDRL test
  • Cryptococcal antigen
  • Histoplasma antigen
  • Aspergillus galactomannan antigen
  • Coccidioides antibody by complement fixation or immunodiffusion
  • PCR for tuberculosis, Whipple disease, enterovirus, and lymphoma
  • Culture for enterovirus and Acanthamoeba
• Blood tests
  • RPR or other routine syphilis screening
  • Serology for Coccidioides, Histoplasma, Toxoplasma, and Brucella antibodies
  • Serology for Histoplasma antigen (may be from blood or urine)
• Brain biopsy has low diagnostic yield in chronic meningitis