What is meningitis?

Meningitis is an inflammation of the meninges, the membranes that surround the brain. There are three meninges, including the following:

  • Dura mater - the outside membrane that adheres to the inside of the skull.

  • Arachnoid - the middle membrane.

  • Pia mater - the innermost membrane, which adheres to the brain.

What causes meningitis?

There are two distinct types of meningitis, each with different causes:

Viral - caused by a virus

  • Viral meningitis is more common than bacterial meningitis, although rarely life threatening. Viral meningitis can be caused by different viruses, and is spread between people by coughing or sneezing, or through poor hygiene. Other germs can be found in sewage polluted water. On rare occasions, certain insects - like mosquitos and ticks - are thought to pass on these viruses. Insect bites would then be the way the virus is introduced into a patient, with the spread of the virus from the blood to the brain.

  • Viral meningitis can, in rare circumstances, be helped by special antiviral medications that specifically target certain viruses. Recovery is normally complete, but headaches, fatigue, and depression may persist.

Bacterial - caused by a bacterium

  • Bacterial meningitis, although rare, may be fatal.

  • Bacteria may be spread through the exchange of respiratory and throat secretions, such as coughing and kissing, but they cannot live outside the body for long. They cannot be picked up from water supplies, swimming pools, buildings, etc.

  • Many species of bacteria can cause meningitis. Below are four types: 

    • Neisseria meningitidis (meningococcus) Meningococcus is common in children two to 18 years of age. It is spread by respiratory droplets and close contact. For unknown reasons, only a small fraction of carriers develop meningitis. Meningococcal meningitis occurs most often in the first year of life, but may also occur in closed populations, such as schools.

    • Streptococcus pneumoniae (pneumococcus)

      Pneumococcus is the most common and most serious form of bacterial meningitis. Those at high risk may include persons with weakened immune systems.

    • Haemophilus influenzae b

      The development of the Haemophilus influenzae b vaccine has drastically decreased the number of cases in the U.S. Children who do not have access to the vaccine and those in day-care centers are at high risk of acquiring Haemophilus meningitis.

    • Listeria monocytogenes

      Listeria monocytogenes has become a more frequent cause of meningitis in neonates, pregnant women, persons over the age of 60, and in persons of all ages who are immunocompromised.

How does the infection reach the brain?

The infection can reach the brain via several different routes, including through the bloodstream from another infected part of the body, through the bones of the skull from infected sinuses or inner ears, or from a head injury, such as a fractured skull or penetrating wound. In particular, this occurs when the body's resistance is compromised by certain factors such as following surgery or an extended hospitalization, a weakened immune system, or as a result of chronic kidney failure.

What are the symptoms of meningitis?

The following are the most common symptoms of meningitis. However, each individual may experience symptoms differently. Symptoms may include:

  • Fever

  • Headache

  • Nausea and vomiting

  • Stiff neck

  • Photophobia (low tolerance to bright light)

  • Confusion

  • Joint aches or pains

  • Drowsiness

  • Seizures

Symptoms for children may also include:

  • Fever

  • High-pitched cry

  • Pale, blotchy skin color

  • Not wanting to eat

  • Vomiting

  • Fretful and fussy

  • Arching back

  • Difficult to wake

It is important to note that these symptoms may not occur all at once, nor in everyone who contracts meningitis. The symptoms of meningitis may resemble other conditions or medical problems. Always consult your physician for a diagnosis.

How is meningitis diagnosed?

In addition to a complete medical history and physical examination, diagnostic procedures for meningitis may include the following:

  • Lumbar puncture (spinal tap) - a special needle is placed into the lower back, into the spinal canal. This is the area around the spinal cord. The pressure in the spinal canal and brain can then be measured. A small amount of cerebral spinal fluid (CSF) can be removed and sent for testing to determine if there is an infection or other problems. CSF is the fluid that bathes the brain and spinal cord.

  • Blood testing

  • Computed tomography scan (Also called a CT or CAT scan.) - a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.

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