Tuberculous Meningitis Differential Diagnoses

Updated: Dec 07, 2017
  • Author: Tarakad S Ramachandran, MBBS, MBA, MPH, FAAN, FACP, FAHA, FRCP, FRCPC, FRS, LRCP, MRCP, MRCS; Chief Editor: Niranjan N Singh, MBBS, MD, DM, FAHS, FAANEM  more...
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DDx

Diagnostic Considerations

Tuberculous meningitis (TBM) continues to pose a diagnostic problem. A high index of clinical suspicion is absolutely essential. TBM should be a strong consideration when a patient presents with a clinical picture of meningoencephalitides, especially in high-risk groups, including persons with malnutrition, those who abuse alcohol or drugs, homeless persons, people in correctional facilities, residents of long-term care facilities, and patients with known HIV infection.

Diagnostic confusion often exists between TBM and other meningoencephalitides, in particular partially treated meningitis. Acid-fast bacilli are seen in only approximately 25% of cerebrospinal fluid (CSF) smears. CSF culture is time-consuming and seldom yields positive results. The sensitivities of many of the new tests are still under study, and these tests may not become generally available for some time; when they do, they are likely to prove costly.

In one study, 5 features independently predicted the diagnosis of TBM:

  • Prodromal stage lasting 7 days or longer
  • Optic atrophy on fundal examination
  • Focal deficit
  • Abnormal movements

CSF leukocytes comprising less than 50% polymorphonuclear leukocytes

Validation of these criteria on another set of 128 patients revealed a sensitivity of 98.4% if at least one feature was present and a specificity of 98.3% if 3 or more were present. This simple rule is useful for physicians working in regions where TB is prevalent.

TBM must be differentiated not only from other forms of acute and subacute meningitis but also from conditions such as viral infections and cerebral abscess. The radiological differential diagnosis includes cryptococcal meningitis, cytomegalovirus encephalitis, sarcoidosis, meningeal metastases, and lymphoma.

TB of any form is a notifiable disease in the United States. Mandatory notification of the appropriate health department is the responsibility of the physician who makes the diagnosis.

Other problems to be considered

TBM should be considered in the differential diagnosis in any patient presenting with fever and a change in sensorium. Other problems to be considered include the following:

  • Infections: Fungal (cryptococcal, histoplasmosis, actinomycetic, nocardiasis, Arachnia infection, candidiasis, coccidiosis); spirochetal (Lyme disease, syphilis, leptospirosis); bacterial (partially treated bacterial meningitis, brain abscess, listeriosis, Neisseria species infection, tularemia); brucellosis; parasitic (cysticercosis, acanthamebiasis, angiostrongylosis, toxoplasmosis, trypanosomiasis); and viral (herpes, mumps, retrovirus, enterovirus [in hypogammaglobulinemics])
  • Acute hemorrhagic leukoencephalopathy
  • Behçet disease
  • Chemical meningitis
  • Chronic benign lymphocytic meningitis
  • Neoplastic: metastatic, lymphoma
  • Systemic lupus erythematosus
  • Vascular: Multiple emboli, subacute bacterial endocarditis, sinus thrombosis
  • Vasculitis: Isolated central nervous system (CNS) angiitis, systemic giant cell arteritis, Wegener granulomatosis, polyarteritis nodosa, noninfectious granulomatosis, lymphomatoid granulomatosis
  • Vogt-Koyanagi-Harada syndrome

Differential Diagnoses