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What Is Encephalitis? What Causes Encephalitis?

What Is Encephalitis? What Causes Encephalitis?


Encephalitis is an inflammation of the brain. It usually results from an infection, most often by a virus, but sometimes by bacteria, a fungus, or parasites. In rare cases, it is caused by brain injury, a drug or vaccine reaction, or poison.

A virus, or other germ in the blood stream, can be carried to the brain. Germs in the brain attract white blood cells, the body's main line of defense against invaders, and this sets up an inflammatory reaction. The brain tissue then swells (called cerebral edema); bleeding may occur within the brain (called intracerebral hemorrhage), and brain damage may occur.

About 1 in 200,000 people develop encephalitis each year in the United States. While anyone can succumb, children, the elderly, and those with weakened immune systems are more vulnerable.

What Is Encephalitis?

What Are The Symptoms

The symptoms of encephalitis may vary widely depending on the cause and severity. They range from no symptoms in very mild cases, to more severe symptoms, including:

  • Muscle weakness; unsteadiness standing up or trouble walking
  • Headache, fatigue, fever, neck pain
  • Stiff neck
  • Nausea and vomiting
  • A foul mood, irritability
  • Aversion to light; squinting
  • Seizures
  • Clumsiness
  • Mental confusion
  • Drowsiness
  • A coma (in severe cases)

Babies may not show symptoms as distinctly. Their bodies may become weak or limp and they may squint or turn away from a light source.

How Is Encephalitis Treated?

During The "Acute" Phase (while the patient is actively ill with encephalitis)

This phase usually lasts a week or two, after which symptoms resolve gradually or sometimes suddenly.

Because it is often difficult to ascertain the cause of encephalitis, doctors generally prescribe an antibiotic immediately until a bacterial cause can be ruled out.

If herpes virus is suspected, doctors will put the patient on the anti-viral drug acyclovir, usually given intravenously. This is normally done right away because the medicine can help if given early enough. It can also be discontinued if another cause is found.

If the illness is caused by an enterovirus or arbovirus, patients are usually treated for their symptoms and made as comfortable as possible.

  • A quiet, dark environment and medication for headaches is most helpful.
  • Narcotics are sometimes given for pain, but used sparingly to avoid any drug-induced changes in brain function.
  • Drugs like dexamethasone (a steroid) injections or other steroids may be given to reduce the inflammation and swelling of the brain.
  • If seizures occur, they will require treatment with anti-convulsant medications.
  • In rare, severe cases where the patient is unconscious, he or she may need help with breathing. Patients are monitored closely to watch for any possible complications.

For post-infectious encephalomyelitis, doctors can do little more than make the patient comfortable. There have been some reports that corticosteroid treatments may help, although there is not much data available at this point.

After The Inflammation Has Subsided

As the patient recovers, the focus often shifts to rehabilitation if there appears to be any lingering neurological problems. Follow-up evaluations for psychiatric, intellectual, vision or hearing abnormalities are usually warranted. If problems are found, a rehabilitation specialist can prepare a course of treatment to correct them.

Many cases of encephalitis are linked to viruses. The expanding research in virology triggered by the AIDS epidemic may lead to better drugs to combat viral forms of the illness in the future.

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