Encephalitis (en-sef-uh-LIE-tis) is inflammation of the brain. It can be caused
by viral or bacterial infections, or by immune cells mistakenly attacking the
brain. Viruses that can lead to encephalitis can be spread by insects such as
mosquitos and ticks.
When inflammation is caused by an infection in the brain, it's known as
infectious encephalitis. And when it's caused by the immune system
attacking the brain, it's known as autoimmune encephalitis. Sometimes there
is no known cause.
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Muscle weakness.
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Trouble with speech or hearing.
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Loss of consciousness, including coma.
In infants and young children, symptoms also might include:
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Bulging of the soft spots of an infant's skull.
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Nausea and vomiting.
Encephalitis can sometimes lead to death. Getting diagnosed and treated
right away is important because it's hard to predict how encephalitis may
affect each person.
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Stiffness affecting the whole body.
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Poor feeding or not waking for a feeding.
Symptoms
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Irritability.
Encephalitis may cause many different symptoms including confusion,
personality changes, seizures or trouble with movement. Encephalitis also
may cause changes in sight or hearing.
In autoimmune encephalitis, symptoms may develop more slowly over
several weeks. Flu-like symptoms are less common but can sometimes
happen weeks before more-serious symptoms start. Symptoms are different
for everyone, but it's common for people to have a combination of symptoms,
including:
Most people with infectious encephalitis have flu-like symptoms, such as:
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Changes in personality.
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Headache.
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Memory loss.
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Fever.
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Aches in muscles or joints.
Trouble understanding what is real and what is not, known as
psychosis.
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Fatigue or weakness.
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Seeing or hearing things that aren't there, known as
hallucinations.
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Seizures.
Typically, these are followed by more-serious symptoms over a period of
hours to days, such as:
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Changes in vision.
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Stiff neck.
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Sleep problems.
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Confusion, agitation or hallucinations.
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Muscle weakness.
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Seizures.
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Loss of sensation.
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Loss of feeling or being unable to move certain areas of the
face or body.
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Trouble walking.
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Irregular movements.
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Irregular movements.
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Bladder and bowel symptoms.