Meningitis is an infection which causes inflammation of the
membranes covering the brain and spinal cord. Non-bacterial meningitis is often referred
to as "aseptic meningitis." Bacterial meningitis may be referred to as
Information about Meningitis
The most common causes of meningitis are viral infections that
usually resolve without treatment. However, bacterial infections of the
extremely serious illnesses, and may result in death or brain damage even if treated.
Meningitis is also caused by fungi, chemical irritation or drug allergies, and tumors.
- meningitis - cryptococcal
- syphilitic aseptic meningitis
- meningitis - H. influenza
- meningitis - meningococcal
- meningitis - pneumococcal
- meningitis - staphylococcal
- meningitis - tuberculosis
- aseptic meningitis
- meningitis gram negative
- carcinomatous meningitis (meningitis due to cancer)
Acute bacterial meningitis is a true medical emergency, and requires immediate
hospital-based treatment. Bacterial strains that cause meningitis include Streptococcus
pneumoniae, Haemophilus influenzae, Neisseria meningitidis
(meningococcus), Listeria monocytogenes, and many other types of bacteria. In the
U.S. about 17,500 cases of bacterial meningitis occur each year.
Viral meningitis is milder and occurs more often than bacterial meningitis. It usually
develops in the late summer and early fall, often affects children and adults under 30.
Seventy percent of the infections occur in children under the age of 5. Most viral
meningitis is associated with enteroviruses, which are viruses that commonly cause stomach
flu. However, many other types of viruses can also cause meningitis; for example, viral
meningitis may occur as a complication in people with genital herpes.
Symptoms of Meningitis
- fever and chills
- headache, severe
- nausea and vomiting
- stiff neck ("meningismus")
- sensitivity to light (photophobia)
- mental status changes
Additional symptoms that may be associated with this disease:
- consciousness, decreased
- breathing, rapid
- opisthotonos (severe neck stiffness, ultimately resulting in a characteristic arched
posture-seen in infants or small children)
- "bulging fontanelles" may be seen in infants
- poor feeding or irritability in children
Meningitis is an important cause of fever in newborn children. For this reason, a
lumbar puncture is often done on newborns who have a fever of uncertain origin.
Diagnosis of Meningitis
A number of techniques are used when examining a patient suspected of having meningitis
to verify the diagnosis. Certain manipulations of the head (lowering the head, chin
towards chest, for example) are difficult to perform and painful for a patient with
The most important test used to diagnose meningitis is the lumbar puncture (commonly
called a spinal tap). Lumbar puncture (LP) involves the insertion of a thin needle into a
space between the vertebrae in the lower back and the withdrawal of a small amount of CSF.
The CSF is then examined under a microscope to look for bacteria or fungi. Normal CSF
contains set percentages of glucose and protein. These percentages will vary with
bacterial, viral, or other causes of meningitis. For example, bacterial meningitis causes
a greatly lower than normal percentage of glucose to be present in CSF, as the bacteria
are essentially "eating" the host's glucose, and using it for their own
nutrition and energy production. Normal CSF should contain no infection-fighting cells
(white blood cells), so the presence of white blood cells in CSF is another indication of
meningitis. Some of the withdrawn CSF is also put into special lab dishes to allow growth
of the infecting organism, which can then be identified more easily. Special immunologic
and serologic tests may also be used to help identify the infectious agent.
In rare instances, CSF from a lumbar puncture cannot be examined because the amount of
swelling within the skull is so great that the pressure within the skull (intracranial
pressure) is extremely high. This pressure is always measured immediately upon insertion
of the LP needle. If it is found to be very high, no fluid is withdrawn because doing so
could cause hernia ion of the brain stem. Hernia ion of the brain stem occurs when the
part of the brain connecting to the spinal cord is thrust through the opening at the base
of the skull into the spinal canal. Such hernia ion will cause compression of those
structures within the brain stem that control the most vital functions of the body
(breathing, heart beat, consciousness). Death or permanent debilitation follows
of the brain stem.
Treatment of Meningitis
Antibiotic medications (forms of penicillin and cephalosporins, for example) are the
most important element of treatment against bacterial agents of meningitis. Because of the
effectiveness of the blood-brain barrier in preventing the passage of substances into the
brain, medications must be delivered directly into the patient's veins (intravenously, or
by IV), at very high doses. Antiviral drugs (acyclovir) may be helpful in shortening the
course of viral meningitis, and antifungal medications are available as well.
Other treatments for meningitis involve decreasing inflammation (with steroid
preparations) and paying careful attention to the balance of fluids, glucose, sodium,
potassium, oxygen, and carbon dioxide in the patient's system. Patients who develop
seizures will require medications to halt the seizures and prevent their return.
Prognosis of Meningitis
Viral meningitis is the least severe type of meningitis, and patients usually recover
with no long-term effects from the infection. Bacterial infections, however, are much more
severe, and progress rapidly. Without very rapid treatment with the appropriate
antibiotic, the infection can swiftly lead to coma and death in less than a day's time.
While death rates from meningitis vary depending on the specific infecting organism, the
overall death rate is just under 20%.
The most frequent long-term effects of meningitis include deafness and blindness, which
may be caused by the compression of specific nerves and brain areas responsible for the
senses of hearing and sight. Some patients develop permanent seizure disorders, requiring
life-long treatment with anti-seizure medications. Scarring of the meninges may result in
obstruction of the normal flow of CSF, causing abnormal accumulation of CSF. This may be a
chronic problem for some patients, requiring the installation of shunt tubes to drain the
Prevention of Meningitis
Prevention of meningitis primarily involves the appropriate treatment of other
infections an individual may acquire, particularly those that have a track record of
seeding to the meninges (such as ear and sinus infections). Preventive treatment with
antibiotics is sometimes recommended for the close contacts of an individual who is ill
with meningococcal or H. influenzae type b meningitis. A meningococcal vaccine
exists, and is sometimes recommended to individuals who are traveling to very high risk
areas. A vaccine for H. influenzae type b is now given to babies as part of the
standard array of childhood immunizations.