Meningitis (from Greek mninx, "membrane"[1] and the medical suffix -itis,
"inflammation") is an acute inflammation of the protective membranes covering the brain and
spinal cord, known collectively as the meninges.[2] The inflammation may be caused by infection
with viruses, bacteria, or other microorganisms, and less commonly by certain drugs.[3]
Meningitis can be life-threatening because of the inflammation's proximity to the brain and
spinal cord; therefore, the condition is classified as a medical emergency.[2][4]
The most common symptoms of meningitis are headache and neck stiffness associated with
fever, confusion or altered consciousness, vomiting, and an inability to tolerate light
(photophobia) or loud noises (phonophobia). Children often exhibit only nonspecific symptoms,
such as irritability and drowsiness. If a rash is present, it may indicate a particular cause of
meningitis; for instance, meningitis caused by meningococcal bacteria may be accompanied by a
characteristic rash.[2][5]
A lumbar puncture diagnoses or excludes meningitis. A needle is inserted into the spinal canal to
extract a sample of cerebrospinal fluid (CSF), that envelops the brain and spinal cord. The CSF is
examined in a medical laboratory.[4] The first treatment in acute meningitis consists of promptly
administered antibiotics and sometimes antiviral drugs. Corticosteroids can also be used to
prevent complications from excessive inflammation.[4][5] Meningitis can lead to serious long-term
consequences such as deafness, epilepsy, hydrocephalus and cognitive deficits, especially if not
treated quickly.[2][5] Some forms of meningitis (such as those associated with meningococci,
Haemophilus influenzae type B, pneumococci or mumps virus infections) may be prevented by
immunization.[2] In 2013 meningitis resulted in 303,000 deaths down from 464,000 deaths in
1990.[6]
Contents
1 Signs and symptoms
o 1.1 Clinical features
o 1.2 Early complications
2 Causes
o 2.1 Bacterial
o 2.2 Viral
o 2.3 Fungal
o 2.4 Parasitic
o 2.5 Non-infectious
3 Mechanism
4 Diagnosis
o 4.1 Blood tests and imaging
o 4.2 Lumbar puncture
o 4.3 Postmortem
5 Prevention
o 5.1 Behavioral
o 5.2 Vaccination
o 5.3 Antibiotics
6 Management
o 6.1 Bacterial meningitis
o 6.2 Viral meningitis
o 6.3 Fungal meningitis
7 Prognosis
8 Epidemiology
9 History
10 References
11 External links
Signs and symptoms
Clinical features
Neck stiffness, Texas meningitis epidemic of 191112.
In adults, the most common symptom of meningitis is a severe headache, occurring in almost
90% of cases of bacterial meningitis, followed by nuchal rigidity (the inability to flex the neck
forward passively due to increased neck muscle tone and stiffness).[7] The classic triad of
diagnostic signs consists of nuchal rigidity, sudden high fever, and altered mental status;
however, all three features are present in only 4446% of bacterial meningitis cases.[7][8] If none
of the three signs are present, acute meningitis is extremely unlikely.[8] Other signs commonly
associated with meningitis include photophobia (intolerance to bright light) and phonophobia
(intolerance to loud noises). Small children often do not exhibit the aforementioned symptoms,
and may only be irritable and look unwell.[2] The fontanelle (the soft spot on the top of a baby's
head) can bulge in infants aged up to 6 months. Other features that distinguish meningitis from
less severe illnesses in young children are leg pain, cold extremities, and an abnormal skin color.
[9][10]
Nuchal rigidity occurs in 70% of bacterial meningitis in adults.[8] Other signs of meningism
include the presence of positive Kernig's sign or Brudziski sign. Kernig's sign is assessed with
the person lying supine, with the hip and knee flexed to 90 degrees. In a person with a positive
Kernig's sign, pain limits passive extension of the knee. A positive Brudzinski's sign occurs when
flexion of the neck causes involuntary flexion of the knee and hip. Although Kernig's sign and
Brudzinski's sign are both commonly used to screen for meningitis, the sensitivity of these tests
is limited.[8][11] They do, however, have very good specificity for meningitis: the signs rarely
occur in other diseases.[8] Another test, known as the "jolt accentuation maneuver" helps
determine whether meningitis is present in those reporting fever and headache. A person is asked
to rapidly rotate the head horizontally; if this does not make the headache worse, meningitis is
unlikely.[8]
Meningitis caused by the bacterium Neisseria meningitidis (known as "meningococcal
meningitis") can be differentiated from meningitis with other causes by a rapidly spreading
petechial rash, which may precede other symptoms.[9] The rash consists of numerous small,
irregular purple or red spots ("petechiae") on the trunk, lower extremities, mucous membranes,
conjuctiva, and (occasionally) the palms of the hands or soles of the feet. The rash is typically
non-blanching; the redness does not disappear when pressed with a finger or a glass tumbler.
Although this rash is not necessarily present in meningococcal meningitis, it is relatively specific
for the disease; it does, however, occasionally occur in meningitis due to other bacteria.[2] Other
clues on the cause of meningitis may be the skin signs of hand, foot and mouth disease and
genital herpes, both of which are associated with various forms of viral meningitis.[12]
