Chronic meningitis

Chronic meningitis is a long-lasting inflammation of the meninges, the membranes that line the brain and spinal cord, defined by signs, symptoms and inflammation that persist for more than four weeks. Infectious causes are a leading cause, and the bacteria, fungi and viruses responsible differ from those behind acute infectious meningitis. Tuberculosis and the fungus cryptococcus are the leading causes worldwide, and the infectious forms are more common in people who are immunosuppressed, including those with HIV infection, and in malnourished children. The course is often more insidious than in acute meningitis, and the organisms are hard to isolate from cerebrospinal fluid, so diagnosis is difficult; in about a third of cases no cause is found at first evaluation. Brain MRI is more sensitive than CT but shows no pathognomonic signs. Treatment of the infectious form is directed at the underlying organism.