American Medical Association Family Medical Guide - American Medical Association [435]
The most common cause of meningitis is a virus that is spread when an infected person coughs or sneezes. Viral meningitis (also called aseptic meningitis) is usually relatively mild. Most of the time, a person with viral meningitis will recover in a few days or weeks. Symptoms of viral meningitis may be uncomfortable but usually do not cause permanent damage to the nervous system.
Untreated bacterial meningitis can be fatal or cause permanent brain or nerve damage, including blindness, deafness, or mental deterioration. Infants and young children, older people, or people who have an impaired immune system (such as those who have a chronic illness or who are taking drugs that suppress the immune system) have an increased risk of permanent nerve damage and death.
Vaccination for Meningitis
Widespread immunization of American children has markedly reduced the incidence of Haemophilus influenzae type b (Hib), which used to be the most common cause of bacterial meningitis in children. Because bacterial meningitis can be life-threatening, many doctors recommend that people who are at risk of developing the infection be vaccinated against it. People who are at increased risk include the very young or very old, people who live in close contact (such as in military housing or college dormitories), and people with an impaired immune system (such as those who have a chronic illness or who are taking drugs that suppress the immune system). Vaccines are also available for infections caused by Neisseria meningitidis (which causes meningococcal meningitis) and Streptococcus pneumoniae.
Symptoms
A severe headache, a stiff neck, abnormal sensitivity of the eyes to light (photophobia), nausea and vomiting, and fever usually develop within a few hours of exposure to the bacteria that cause bacterial meningitis. If bacterial meningitis is not treated promptly, you may become sleepy and lose consciousness. You may also develop a deep red or purple rash. Seizures may occur, especially in children, and the soft spot on the top of an infant’s head may bulge and be tightly drawn because of swelling over the brain. In viral meningitis, symptoms are milder but still may include headache, a stiff neck, nausea, and photophobia.
The symptoms of meningitis can be less evident in infants and young children, older people, and people with an impaired immune system because they may have a less active immune response. In these cases, a change in responsiveness along with fever or headache may prompt the doctor to check for meningitis.
Diagnosis
If you have symptoms of meningitis (particularly a stiff neck, headache, and photophobia), your doctor may perform a procedure called lumbar puncture (see below) in which a sample of cerebrospinal fluid (the liquid that surrounds the brain and spinal cord) is taken from your spine. If the cerebrospinal fluid is cloudy and contains pus-filled cells, the meninges are likely to be infected with bacteria, and the doctor will prescribe antibiotics immediately. At the same time, he or she will send the fluid to a laboratory to identify the specific bacterium that is causing the infection and to determine which antibiotic is most effective against it.
If the fluid is clear, meningitis still may be present, but it is more likely caused by a virus. A doctor can sometimes determine what virus caused the infection by drawing blood samples immediately and again several weeks later (to see if your immune system has produced antibodies against it). In most cases of viral meningitis, the only treatment needed is pain relief and rest.
Lumbar puncture
A lumbar puncture (formerly called a spinal tap) is a procedure used mostly to diagnose and treat disorders of the brain and spinal cord. For a diagnosis, a doctor