Tuberculous meningitis overview
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Tuberculous meningitis is Mycobacterium tuberculosis infection of the meninges. It is the most common form of CNS tuberculosis.
Causes
Tuberculous meningitis is caused by Mycobacterium tuberculosis, the bacteria that causes tuberculosis. The bacteria spreads to the brain and spine from another site in the body. Tuberculous meningitis is a very rare disorder in the U.S.
Diagnosis
History and Symptoms
Fever and headache are the cardinal features. Confusion is a late feature and coma bears a poor prognosis. Meningism is absent in a fifth of patients with TB meningitis. Patients may also have focal neurological deficits.
Laboratory Findings
Diagnosis of TB meningitis is made by analysing CSF collected by lumbar puncture. When collecting CSF for suspected TB meningitis, a minimum of 1ml of fluid should be taken (preferably 5 to 10ml).
CT
Imaging studies such as CT or MRI may show features strongly suggestive of TB meningitis, but cannot diagnose it.
Treatment
Medical Therapy
The treatment of TB meningitis is isoniazid, rifampicin, pyrazinamide and ethambutol for two months, followed by isoniazid and rifampicin alone for a further ten months. Steroids are always used in the first six weeks of treatment (and sometimes for longer). A few patients may require immunomodulatory agents such as thalidomide. Treatment must be started as soon as there is a reasonable suspicion of the diagnosis. Treatment must not be delayed while waiting for confirmation of the diagnosis.
Surgery
Hydrocephalus occurs as a complication in about a third of patients with TB meningitis and will require a ventricular shunt.
Primary Prevention
The BCG vaccine may help prevent severe forms of tuberculosis, such as meningitis, in very young children who live in areas where the disease is common.