Sunday, January 15, 2006

meningitis

Meningitis is an inflammation or infection of the lining of the brain and spinal cord. The three major categories of meningitis are bacterial, fungal, and viral. Rarely, infections are secondary to protozoa (e.g., amoeba, Toxoplasma) and other parasites. One of the most silent neurologic abnormalities of old age is meningitis. All elderly who show mental confusion, disorientation, or coma should be carefully evaluated for meningitis.
The most common bacteria that cause meningitis are Pneumococcus and Meningococcus. Fungal meningitis forms include cryptococcal, coccidioidal, and histoplasmal. Viral meningitis is most frequently caused by enteroviruses (coxsackie, ECHO, polio), mumps, and lymphocytic choriomeningitis virus. Sporadic viral encephalitis is primarily caused by herpes simplex, whereas epidemics of encephalitis are frequently due to arboviruses (those borne by arthropods). Infecting agents gain access to the central nervous system primarily through the circulatory system. Bacterial meningitis in the elderly is frequently associated with an underlying illness such as diabetes, decubitus ulcers (pressure sores), or following neurosurgery or trauma to the central nervous system.
The most common symptoms of meningitis are fever, headache, stiff neck, and alterations in the state of consciousness. In the elderly, it may be difficult to separate these symptoms from their underlying disorder. Confusion, stupor, and headache are usually present. Lumbar puncture usually confirms the suspicion of meningitis. Treatment of sporadic meningitis without associated illness is with penicillin or chloramphenicol in penicillin-sensitive people.
Staphylococcal infections should be treated with nafcillin or an equivalent drug. Gram negative organisms should be treated with carbenicillin, chloramphenicol, moxalactam, or cefotaxime. Fungal meningitis is usually treated by the intravenous or intrathecal administration of amphotericin B. The only form of viral encephalitis that responds to therapy is herpes simplex-induced encephalitis. This is treated with adenine arabinoside for 10 days. Biopsy of brain tissue is usually required to make this diagnosis.
Covington, T., and Walker, J. Current Geriatric Therapy. Philadelphia: W. B. Saunders, 1984.

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