Introduction to meningitis

[Tariq Zaki]

Meningitis is inflammation of the layers of tissue that cover the brain and spinal cord (meninges) and of the fluid-filled space between the meninges (subarachnoid space).

Meningitis can be caused by bacteria, viruses, or fungi, by disorders that are not infections, or by drugs.
Meningitis symptoms include fever, headache, and a stiff neck that makes lowering the chin to chest difficult or impossible, although infants may not have a stiff neck and symptoms may differ in the very old and in people who take drugs that suppress the immune system.
A spinal tap is done to obtain a sample of cerebrospinal fluid for analysis.
Treatment of meningitis depends on the cause (for example, antibiotics for bacterial meningitis) and includes drugs to relieve symptoms.

The brain and spinal cord are covered by three layers of tissue called meninges. These layers are the

Dura mater (outermost)
Arachnoid membrane (middle)
Pia mater (innermost)

Between the arachnoid membrane and pia mater is the subarachnoid space. This space contains cerebrospinal fluid, which flows through the meninges, fills the spaces within the brain, and helps cushion the brain and spinal cord.
Most often, meningitis is caused by

Infection with microorganisms such as bacteria, viruses, or fungi

However, certain drugs and disorders that are not infections occasionally cause meningitis (called noninfectious meningitis). These disorders include the following:

Sarcoidosis
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