Meningitis - Description

Any time a part of the body is infected, it is likely to become inflamed and swollen. These symptoms are especially serious in the brain. The brain is enclosed in the skull, a bony structure that cannot change size. If the brain swells, it pushes outward against the skull. Brain cells may become squeezed and begin to die. Brain cells are some of the only kinds of cells in the body that do not regenerate (renew) themselves. Once they die, they cannot be replaced.

An infection in the brain can cause damage in a second way. Brain cells are very delicate. They require just the right balance of chemicals, including sugar, sodium, calcium, potassium, and oxygen. An infection can change the balance of chemicals in the brain. Brain cells may receive too much of one chemical or too little of another. This loss of chemical balance can also kill brain cells.

Meningitis is a serious medical problem because it is difficult to treat. Blood flows into the brain from the neck through a network of blood vessels. This network contains special cells that prevent many chemicals from passing into the brain. This system is known as the blood-brain barrier.

The blood-brain barrier prevents harmful substances from getting into the brain. The blood-brain barrier "knows" which substances the brain needs and which will damage brain cells.

The problem is that the blood-brain barrier usually does not recognize drugs as "good" chemicals. It prevents them from passing into the brain, where they could help clear up an infection. Doctors often have to find other ways to treat the kinds of infection that cause meningitis.