Meningitis is an inflammation of the arachnoid, the pia mater, and the intervening
cerebrospinal fluid (CSF). The inflammatory process extends throughout the
subarachnoid space about the brain and spinal cord and regularly involves the
Causes of meningitis:
Meningitis is caused by different bacteria, viruses, mycobacterium tuberculosis,
inflammatory diseases like SLE(systemic lupus erythematosis),behcet disease.
Because bacterial infections are the most serious and can be life-threatening,
identifying the source of the infection is an important part of developing a
Acute bacterial meningitis usually occurs when bacteria enter the bloodstream
and migrate to the brain and spinal cord. But it can also occur when bacteria
directly invade the meninges, as a result of an ear or sinus infection or a skull
A number of strains of bacteria can cause acute bacterial meningitis. The most
Streptococcus pneumoniae (pneumococcus). This bacterium is the most
common cause of bacterial meningitis in infants, young children and adults
in the United States. It more commonly causes pneumonia or ear or sinus
Neisseria meningitidis (meningococcus). This bacterium is another leading
cause of bacterial meningitis. Meningococcal meningitis commonly occurs
when bacteria from an upper respiratory infection enter your bloodstream.
This infection is highly contagious. It affects mainly teenagers and young
adults, and may cause local epidemics in college dormitories, boarding
schools and military bases.
Haemophilus influenzae (haemophilus). Before the 1990s, Haemophilus
influenzae type b (Hib) bacterium was the leading cause of bacterial
meningitis in children. But new Hib vaccines — available as part of the
routine childhood immunization schedule in the United States — have
greatly reduced the number of cases of this type of meningitis. When it
occurs, it tends to follow an upper respiratory infection, ear infection (otitis
media) or sinusitis.
Listeria monocytogenes (listeria). These bacteria can be found almost
anywhere, in soil, in dust and in foods that have become contaminated.
Contaminated foods have included soft cheeses, hot dogs and luncheon
meats. Fortunately, most healthy people exposed to listeria don't become
ill, although pregnant women, newborns and older adults tend to be more
susceptible. Listeria can cross the placental barrier, and infections in late
pregnancy may cause a baby to be stillborn or die shortly after birth. People
with weakened immune systems, due to disease or medication effect, are
Each year, viruses cause a greater number of cases of meningitis than do bacteria.
Viral meningitis is usually mild and often cures on its own within two weeks. A
group of viruses known as enteroviruses are responsible for about 30 percent of
viral meningitis cases in the United States. As many viral meningitis episodes
never have a specific virus identified as the cause.
The most common signs and symptoms of enteroviral infections are rash, sore
throat, diarrhea, joint aches and headache. These viruses tend to circulate in late
summer and early fall. Viruses such as herpes simplex virus, La Crosse virus, West
Nile virus and others also can cause viral meningitis.
Chronic forms of meningitis is rare and occur when slow-growing organisms
invade the membranes and fluid surrounding your brain. Although acute
meningitis strikes suddenly, chronic meningitis develops over two weeks or more.
Nevertheless, the signs and symptoms of chronic meningitis (headaches, fever,
vomiting and drowsiness) are similar to those of acute meningitis.
Fungal meningitis is relatively uncommon and causes chronic meningitis.
Occasionally it can mimic acute bacterial meningitis. Cryptococcal meningitis is a
common fungal form of the disease that affects people with immune deficiencies,
such as AIDS. It's life-threatening if not treated with an antifungal medication.
Other meningitis causes
Meningitis can also result from noninfectious causes, such as drug allergies, some
types of cancer and inflammatory diseases such as lupus,behcet’s disease.
SYMPTOMS OF MENINGITIS:
The classic signs and symptoms of meningitis are headache, fever, and stiff neck
(in adults and older children). Symptoms of meningitis usually appear suddenly
and can also cause nausea and vomiting. Behavioral changes, such as confusion,
sleepiness, and difficulty waking up, are important symptoms. In infants,
symptoms of meningitis are often much less specific and may include irritability or
tiredness, poor feeding, and fever. Some types of meningitis like bacterial
meningitis can be deadly if not treated promptly. Anyone experiencing symptoms
of meningitis should see a doctor immediately.
Signs Of Meningitis:
Evidence of meningeal irritation (drowsiness), stiff neck, Kernig's and Brudzinski's
signs is usually present. Although the classic triad of fever, stiff neck, and change
in mental status is present in only 44% of episodes, a combination of two of four
symptoms (headache, fever, stiff neck, and altered mental status) is found in 95%
of patients. The findings of meningitis may be easily overlooked in infants or
elderly patients with heart failure or pneumonia, who may have meningitis
without prominent meningeal signs; their lethargy should be investigated
The presence of a petechial, purpuric, or ecchymotic rash in a patient with
meningeal findings almost always indicates meningococcal infection and requires
prompt treatment because of the rapidity with which this infection can progress.
Cranial nerve abnormalities, involving principally the third, fourth, sixth, or
seventh nerve, occur in 5 to 10% of adults with community-acquired meningitis
and usually disappear shortly after recovery. Seizures focal or generalized occur in
20 to 30% of patients.
What is encephalitis?
Encephalitis is an inflammation of the brain. There are many types of encephalitis,
most of which are caused by infections. Most often these infections are caused by
viruses. In addition to infections, encephalitis can also be caused by certain
diseases that result in an inflammation of the brain.
What are encephalitis symptoms and signs?
The signs and symptoms of encephalitis can range from very mild symptoms to
potentially life-threatening. Signs and symptoms of encephalitis include fever,
headache, vomiting, visual sensitivity to light (photophobia), neck stiffness,
confusion, drowsiness, unsteady gait, and irritability. Loss of consciousness, poor
responsiveness, seizures, muscle weakness, sudden severe dementia and memory
loss can also be found in patients with encephalitis.
What is encephalomyelitis?
Encephalomyelitis is inflammation of both the brain and spinal cord.
Encephalomyelitis can be caused by a variety of conditions that lead to irritation
of the brain and spinal cord. Among the common causes of encephalomyelitis are
viruses (for example, herpes zoster virus). People with encephalomyelitis can
exhibit combinations of the various symptoms of either encephalitis or
How are encephalitis and meningitis diagnosed?
Encephalitis or meningitis is suggested when the symptoms described above are
present. The doctor diagnoses encephalitis or meningitis after a completing a
thorough history (asking the patient questions) and examination. The
examination includes special maneuvers to detect signs of inflammation of the
membranes that surround the brain and spinal cord (meninges). These signs are
kernig’s and brudzinsky’s sign. Based on the history and examination, the doctor
suggests specific tests to further help in determining the diagnosis.
Tests that are used in the evaluation of individuals suspected of having
encephalitis or meningitis include evaluation of the blood for signs of infection
and possible presence of bacteria, brain scan (such as CT scan or MRI scan), and
cerebrospinal fluid analysis.
A lumbar puncture is the most common method of obtaining a sample of the fluid
in the spinal canal (the cerebrospinal fluid or CSF) for examination. A lumbar
puncture (also called LP) is the insertion of a needle into the fluid within the spinal
canal. The needle passes between the bony parts of the spine until it reaches the
cerebral spinal fluid. A small amount of fluid is collected and sent to the
laboratory for examination. The evaluation of the spinal fluid is very necessary for
the definite diagnosis and to help make optimal treatment decisions (such as the
appropriate choice of antibiotics).
The diagnosis is confirmed by abnormal spinal fluid results and, in the case of an
infection, by identifying the organism causing the infection. In patients with
meningitis, the CSF fluid often has a low glucose (sugar) level and increased white
blood cell count. The fluid can be used to identify some viral causes of meningitis
(PCR or polymerase chain reaction) or be used to culture bacterial organisms
causing the meningitis.
Blood cultures are also important and should be send prior to start of antibiotics.
Treatment of Meningitis/encephalitis:
Antibiotic and/or antiviral medications need to be considered urgently when the
diagnosis of encephalitis or meningitis is suggested. In some situations,
anticonvulsants are used to prevent or treat seizures. Sometimes corticosteroids
are administered to reduce brain swelling and inflammation. Sedatives may be
needed for irritability or restlessness. Additional medications might be used to
decrease the fever or treat headaches. The need for hospitalization usually
depends on the type of meningitis the patient has and the severity of symptoms.
Increased Intracranial pressure:
Elevation of the patient's head to 30–45°
Intubation and hyperventilation (Paco2 25–30 mm Hg)
Patients with increased ICP should be managed in an intensive care unit.
Treatment of viral encephalitis:
10 mg/kg of acyclovir intravenously every 8 h for 14–21 days. CSF PCR can
be repeated at the completion of this course. Dose adjustment with
impaired renal function.
<3 months ampicillin+ cefotaxime.
Immunocompetent <55 years. Cefotaxime/ ceftriaxone + Vancomycin.
Adults >55 and adults of any age with Ampicillin + cefotaxime, ceftriaxone or
alcoholism /debilitating illness cefepime + vancomycin
Hospital-acquired meningitis, posttraumatic Ampicillin + ceftazidime or meropenem +
or postneurosurgery meningitis, neutropenic vancomycin
patients, or patients with impaired cell-
Complications of meningitis/encephalitis:
When shock occurs in pyogenic meningitis, it is usually a manifestation of
septicemia. Management is guided by the principles of septic shock therapy.
Coagulopathies are frequently associated with the intense bacteremias and
hypotension that can accompany meningitis. The changes may be mild, such as
thrombocytopenia (with or without prolongation of prothrombin and partial
thromboplastin times), or more marked, with clinical evidence of disseminated
Septic Complications :
Patients with pneumococcal meningitis, particularly those with concomitant
bacteremia and pneumonia, can develop acute endocarditis meningitis.
Septic arthritis may result from the bacteremia associated with meningitis caused
by S. pneumoniae, N. meningitidis, or H. influenzae.
Any patient with bacterial meningitis, particularly if meningitis is recurrent, should
be evaluated carefully for any congenital or post-traumatic defects.
What is the prognosis of meningitis/ encephalitis?
The prognosis for encephalitis or meningitis varies. Some cases are mild, short, and
relatively benign and patients have full recovery. Other cases are severe, and
permanent impairment or death is possible. This is usually determined by the type of
infection present and how quickly treatment can be started. Meningitis can lead to
permanent damage to the nervous system and can cause hydrocephalus. The acute
phase of encephalitis may last for one to two weeks, with gradual or sudden resolution
of fever and neurological symptoms. Neurological symptoms may require many
months before full recovery occurs. Some patients may not fully recover from the
With early diagnosis and prompt treatment, many patients recover from meningitis.
Viral meningitis can be self-limiting to 10 days or less, however, in some cases, the
disease progresses so rapidly that death occurs during the first 48 hours, despite early
Is meningitis contagious?
Yes. Especially some forms of bacterial meningitis are contagious. The bacteria are
spread through the exchange of respiratory and throat secretions (for example,
coughing, kissing). Fortunately, none of the bacteria that cause meningitis are as
contagious and they are not spread by casual contact or by simply breathing the air
where a person with meningitis has been. However, sometimes the bacteria that
cause meningitis can spread to other people who have had close or prolonged contact
with a patient with meningitis. Meningitis caused by Neisseria meningitidis (also called
meningococcal meningitis) is the most important example. People in the same
household, dormitory, or day-care center, or anyone with direct contact with a
patient's oral secretions (such as a boyfriend or girlfriend) would be considered at
increased risk of acquiring the infection. This also holds true for health-care
professionals involved in direct, prolonged contact, especially during procedures such
as intubations (placing a breathing tube). People who qualify as close contacts of a
person with meningitis caused by N. meningitidis should receive antibiotics to prevent
them from getting the disease.
Can meningitis be prevented?
Basic steps to avoid spread of organisms, such a hand washing and covering your
mouth when coughing, will also help in decreasing the risk of spreading meningitis.
There are vaccines against Hib (Haemophilus influenzae type B), some strains of N.
meningitidis and many types of Streptococcus pneumoniae.
The vaccines against Hib are considered very safe and highly effective. By 6 months of
age, every infant should receive at least three doses of an Hib vaccine. A fourth dose
("booster") should be given to children between 12 and 18 months of age.
There is also a vaccine that protects against four strains of N. meningitidis, but it is not
routinely used. It is not effective in children under 18 months of age. It is sometimes
used to control outbreaks of some types of meningococcal meningitis in the United
States. College students are typically given the vaccine prior to residence at college.
Some countries experience large, periodic epidemics. Overseas travelers should check
to see if meningococcal vaccine is recommended for their destination. Travelers
should receive the vaccine at least one week before departure.
A vaccine to prevent meningitis due to S. pneumoniae (also called pneumococcal
meningitis) can also prevent other forms of infection due to S. pneumoniae. The
pneumococcal vaccine is not effective in children under 2 years of age, but it is
recommended for all people over 65 years of age and younger people with chronic