Meningitis

From ArticleWorld

Meningitis is characterized by an inflammation of the membrane that covers the brain and the spinal chord. It usually occurs due to infectious causes (pathogens including bacteria, viruses, fungi or parasites), but it can also occur due to various chemical agents or tumors. The associated risk factors include brain abscess and encephalitis.

Causes

The causes of meningitis can be infectious or non-infectious. The usual infectious agents are viruses, but some bacteria (Neisseria meningitidis, Streptococcus pneumoniae and Haemophilius influenzae) can also cause a form of meningitis called bacterial meningitis. Staphylococcus and Escherichia coli can also cause meningitis, along with Mycobacterium tuberculosis. Fungi rarely cause meningitis, but in people with compromised immune system, Cryptococcus neoformans can cause a fungal meningitis.

Non-infectious causes include various tumors like leukemia, lymphoma or brain tumors, sarcoidosis and lead poisoning. Methotrexate is a drug also known to cause meningitis.

Symptoms and diagnosis

There are three common symptoms displayed by meningitis: neck stiffness, headache and photophobia. They are so representative that this trio of symptoms is actually called meningism. Fever, chills and myalgia are usually encountered, along with various neurological deficits like altered state of awareness. Some forms of meningitis may display petechial rash and, in some cases, convulsions.

Diagnosis usually involves an examination of the cerebrospinal fluid. In all cases that raises suspicions of meningitis, a CT scan should be performed and, if it doesn't show any condition that may cause complications during lumbar puncture, a lumbar puncture should be performed. The examination of the fluid sample involves complete blood count, chemical analysis and microbiological analysis.

Treatment and prevention

Meningitis should be treated as a medical emergency because, untreated, it has a very high mortality rate. Antibiotic treatment should start immediately, and it is not uncommon to prescribe broad spectrum antibiotics even before all tests have been completed. Intravenous broad spectrum antibiotics are, in fact, a must, if the lumbar puncture cannot be performed. The range of the treatment may be narrowed when the tests confirm a certain nature of the infection. Antibiotic treatment is usually very efficient, lowering mortality rate to below 15%.

Viral meningitis is more difficult to treat though, since almost no virus responds to antibiotics. The treatment is mainly supportive, in order to allow the immune system to fight the infection by itself.

In either case, corticosteroids may be administered to lower the brain pressure and swelling and in order to prevent the hearing loss that occurs in some cases of meningitis. Sedatives may be given to make the patients more comfortable. Some forms meningitis can be prevented by vaccination, especially in early childhood.