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Meningitis
Meningitis (or spinal meningitis as
it commonly known) is an infection in the meninges
and cerebrospinal fluid. The meninges are three
thin layers of membrane that cover the brain and
spinal cord. The cerebrospinal fluid is watery
layer of cushion just beneath the meninges that
bathes and protects the brain and spinal cord from
physical impact. Meningitis is usually caused by
either a bacteria or virus. Viral meningitis is
generally mild and self-limiting, meaning that it
disappears on its own without any treatment.
Bacterial meningitis, on the other hand, can be
quite severe and can lead to permanent hearing
loss, learning disability, or other types of brain
damage. There are several different bacterial
strains that can cause meningitis, some of which
can be readily treated with antibiotics. HIV
(human immunodeficiency virus) can cause
meningitis at some point during the course of a
person' s illness, but the meningitis is actually
caused by a fungus and not the HIV virus itself.
Most people who are infected with a
bacteria or virus that could potentially cause
meningitis never actually get sick. For example,
according to the Meningitis Research Foundation,
for every 1,000 people who are infected with a
meningitis virus, only one person will actually
become ill. The same is true of bacterial
meningitis. It is not clear these few people
actually develop meningitis from microorganisms
and viruses that are apparently harmless to the
rest of us. It is likely due to a weakness in
their immune system.
Types
Viral Meningitis
Viral meningitis, also known as aseptic
meningitis, is the most common type of meningitis
and is caused by an infection of one of several
different types of viruses. Viral meningitis is
serious but rarely fatal. The symptoms usually
last no more than about 10 days, and then the
person recovers fully without any treatment. The
viruses that cause viral meningitis are contagious
and are very common in the summer and early fall,
but most people who have one of the viruses show
no symptoms of any kind.
Sometimes a person may develop a
cold or a rash, but full-blown meningitis develops
in fewer than 1 in 1,000 people who are infected
with a meningitis virus. Consequently, if you are
around somebody who has viral meningitis, you have
a very small chance of developing it yourself,
even if you get infected. About 90% of all viral
meningitis cases involve a type of virus known as
an enterovirus. The mumps and herpes virus can
also cause meningitis.
Bacterial Meningitis
There are several different types of bacteria that
can cause bacterial meningitis. It is important to
identify the bacteria so that an appropriate
antibiotic can be prescribed. Bacterial meningitis
can progress quickly and can lead to death, so it
is essential that it be diagnosed and treated as
soon as possible. Some forms of bacterial
meningitis are contagious and are spread through
secretions from the mouth or nose, although they
are not nearly as contagious as the common cold or
flu. They are not spread by casual contact.
However, people living in crowded households or
chronic care facilities are at greater risk for
developing bacterial meningitis.
There are vaccines for some types
of bacterial meningitis. Infants in the United
States are routinely vaccinated for the Hib
strain, which used to be the most common cause of
bacterial meningitis in the country. Outbreaks of
meningitis epidemics do occur throughout the
world, though not in the United States.
Cryptococcal Meningitis
Cryptoccal meningitis is a type of meningitis that
develops in HIV patients and is caused by a
fungus. The course of the illness is often a slow
one, with symptoms that may progress over days to
weeks to even months.
Symptoms
No matter what causes meningitis,
the symptoms are the same. The most common
symptoms include headache, a stiff neck, and
fever. In infants, these symptoms may be difficult
to detect. Other symptoms include vomiting,
nausea, photophobia (looking into a light is
disturbing), confusion, sleepiness, and seizures.
Some people may develop a skin rash or joint
pains. Some may have an upper respiratory
infection or other illness before the symptoms of
meningitis start to show.
The symptoms may develop over the course of a few
hours or a few days. They usually develop much
more quickly in bacterial meningitis and, if
untreated, can lead to unconsciousness.
Diagnosis
Clinical & Neurological Exam. One
of the most telling clinical symptoms of
meningitis is a stiff neck. It is extremely
painful for a person with meningitis to move their
neck forward. The neck may be so stiff that if
they try to move it, their whole body moves
instead. Other clinical signs include a skin rash
and a swelling of the nerves in the eye, which
indicates an increased pressure in the brain.
Imaging Studies - A CT scan may be
done to view the brain and rule out other possible
neurological disorders.
Spinal Tap
(Lumbar Puncture) - Both viral and bacterial
meningitis are usually positively diagnosed by
doing a spinal tap, or lumbar puncture, which
involves inserting a needle into the lower back
(the lumbar area of the spine) and collecting some
cerebrospinal fluid. The fluid is then sent to a
lab where it is examined under the microscope and
whatever is causing the infection can be
identified.
Treatment
Most forms of viral meningitis are
self-limiting, that is they disappear on their own
without any treatment. Bacterial meningitis, on
the other hand, can and should be treated with
antibiotics as soon as possible. If bacterial
meningitis is suspected, antibiotics should be
administered even before the spinal fluid is
collected to confirm the diagnosis. Bacterial
meningitis should be considered a potentially
life-threatening emergency. Patients may also
experience secondary symptoms, like changes in
their blood pressure, that need to be treated as
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