Doctor's Notes on Meningitis in Adults
Meningitis is inflammation of the meninges, the membranes that surround the brain and spinal cord. Meningitis can also be associated with inflammation of the brain tissue itself, known as encephalitis. Meningitis may be caused by infections by a number of different viruses, bacteria, fungi, and parasites. It can also be due to non-infectious conditions. Diseases and conditions that can lead to widespread inflammation of body tissues without infection, such as lupus, may cause aseptic (non-bacterial) meningitis. Certain medications may also cause non-infectious or aseptic meningitis.
The characteristic symptoms and signs of meningitis include headache, fever, and a stiff neck. There is usually a painful sensitivity to light, known as photophobia. Associated symptoms can include nausea, vomiting, and behavior changes like confusion, sleepiness, and difficulty awakening.
Meningitis in Adults Symptoms
About 25% of those who develop meningitis have symptoms that develop over 24 hours. The remainder generally become ill over one to seven days. Occasionally, if someone has been on antibiotics for another infection, the symptoms can take longer to develop or may be less intense. If someone is developing fungal meningitis (most commonly someone who is HIV positive), the symptoms may take weeks to develop.
The classic symptoms of meningitis are fever, headache, and stiff neck. Unfortunately, not everyone with meningitis has all of these symptoms. Only approximately 45% of people with meningitis have all three of these classic signs. Almost everyone, however, has at least one of the classic symptoms.
- Classic symptoms
- Headache occurs in most people with meningitis
- Stiff neck occurs in a majority of people with meningitis
- Fever and chills occur in most people with meningitis
- Vomiting occurs in many of people with meningitis
- Extreme sensitivity to bright lights (photophobia)
- History of a recent upper respiratory infection (for example, cold, sore throat)
- Less common symptoms
Meningitis in Adults Causes
Usually, the brain is protected naturally from the body's immune system by the barrier that the meninges create between the bloodstream and the brain itself. Normally, this helps prevent the body from mounting an immune reaction to attack itself. In meningitis, however, this can become a problem.
Once bacteria or other organisms have found their way to the brain, they are somewhat isolated from the immune system and can spread. However, when the body eventually begins to fight the infection, the problem can worsen.
As the body tries to fight the infection, blood vessels become leaky and allow fluid, white blood cells, and other infection-fighting particles to enter the meninges and the brain. This causes brain swelling and can eventually lead to decreased blood flow to parts of the brain, worsening the symptoms of infection.
- Meningitis is usually caused by one of a number of bacteria. The most common is Streptococcus pneumoniae. Neisseria meningitidis can cause outbreaks in crowded conditions, such as college dormitories or military barracks. Haemophilus influenzae type B (Hib) can also cause meningitis in adults and children. Meningitis in children is becoming less common because children now receive the Hib vaccine in infancy as well as the pneumococcal vaccine (Prevnar).
- Bacterial meningitis can occur for a number of reasons. Often it is the result of an infection by bacteria that already live in the nose and mouth. The bacteria enter the blood and become lodged in the brain's outer covering, the meninges.
- Meningitis can also be caused by the spread of an infection occurring near the brain, such as from the ears or the sinuses. It is also an occasional complication of brain, head, or neck surgery.
- The average age for meningitis is 25 years, and meningitis affects both men and women equally. For unclear reasons, African-Americans seem to develop meningitis more frequently than do people of other races.
- Risk factors that place people at higher risk for bacterial meningitis include the following:
- Adults older than 60 years of age
- Children younger than 5 years of age
- People with alcoholism
- People with sickle cell anemia
- People with cancer, especially those receiving chemotherapy
- People who have received transplants and are taking drugs that suppress the immune system
- People with diabetes
- Those recently exposed to meningitis at home
- People living in close quarters (military barracks, dormitories)
- IV drug users
- People with shunts in place for hydrocephalus
- Fungal meningitis is a very serious and rare cause of meningitis. Typically limited to people who have had surgical procedures or have impaired immune systems due to cancer and other diseases affecting immune function, the 2012 outbreak of fungal meningitis was linked to a specific procedure using a specific steroid medication.
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Whether you or someone you know has the condition right now, it’s highly likely that you will know someone with a narrowing spine in the future, as it becomes more common with age. Read further to gain a wealth of information about spinal stenosis. You will learn its different types, its causes, who it impacts, and what you can do about it.
Kasper, D.L., et al., eds. Harrison's Principles of Internal Medicine, 19th Ed. United States: McGraw-Hill Education, 2015.