Encephalitis
En Español (Spanish Version)Encephalitis is inflammation of the brain. The inflammation may involve the whole brain, or just parts of the brain.
Encephalitis
© 2011 Nucleus Medical Media, Inc.
Viral infection of the central nervous system can be asymptomatic, present with mild symptoms, or cause
meningitis
and/or encephalitis. Most cases of encephalitis are caused by a viral infection. Encephalitis may be sporadic or epidemic. In the United States, the most common cause of sporadic encephalitis is the
herpes simplex virus
. Epidemic encephalitis are usually
mosquito
- or tick-borne, which may be dependant on the geography and season.
The most common viruses that cause encephalitis include:
There are also non-viral causes of encephalitis. These are sometimes due to overreaction of the immune system.
A risk factor is something that increases your chance of getting a disease or condition.
Risk factors for encephalitis include:
- Living, working, or playing in an area where mosquito-borne viruses are common
-
Not being immunized against diseases such as:
- Measles
- Mumps
- Chickenpox
- Polio
-
Having
cancer
- Taking immunosuppressive medicines after organ transplant
-
Having
AIDS
The symptoms may range from mild, such as fever and headache, to severe, such as
seizures
, loss of consciousness, and permanent neurological damage. Death may also result.
Symptoms include:
- Fever
- Weakness, severe fatigue
- Headache
- Sensitivity to light
- Stiff neck and back
- Vomiting
- Changes in consciousness
- Muscle aches
- Rash
- Personality changes
- Confusion
- Irritability
- Seizures
-
Partial or complete
paralysis
- Progressive drowsiness
- Yawning
- Trouble walking
- Trouble speaking
- Trouble swallowing
The doctor will ask about your symptoms and medical history, and do a physical exam.
Tests may include:
- Blood tests—to look for signs of infection
- Spinal tap
—to test spinal fluid for signs of infection
- CT
and/or
MRI
scans of the head—to look for abnormal areas of enhancement, hemorrhage, or edema in the brain
- Electroencephalogram
(EEG)—
to look for abnormal electrical activity in the brain
-
Brain
biopsy
—removal of a small sample of brain tissue to test for signs of infection
Treatment is mostly supportive. It may include:
- Antiviral drugs (eg, intravenous acyclovir for herpes simplex encephalitis)—to potentially help shorten the duration of the illness
- Steroid medicines—to decrease brain swelling
- Diuretics such as mannitol—to decrease elevated intracranial pressure
- Intubation with hyperventilation—to decrease elevated intracranial pressure and to maintain respiration and ventilation
- Anticonvulsant medicines—to prevent and/or treat seizures
Make sure that you and your children are vaccinated against preventable viral illnesses.
Encephalitis Information Resource
National Institute of Neurological Disorders and Stroke
Canadian Neurological Sciences Federation
Cecil RL, Goldman L, Bennett JC.
Cecil Textbook of Medicine
. 21st ed. Philadelphia, PA: WB Saunders Company; 2000.
Conn HF, Rakel RE.
Conn's Current Therapy 2001
. 53rd ed. Philadelphia, PA: WB Saunders Company; 2001.
Herpes simplex encephalitis. EBSCO Publishing DynaMed website. Available at:
http://www.ebscohost.com/dynamed/
. Updated December 2, 2007. Accessed February 23, 2008.
Mandell GL, Bennett JE, Dolin R.
Principles and Practice of Infectious Diseases
. 6th ed. New York, NY: Churchill Livingstone; 2004.
Rosen P, Barkin RM, Danzl DF, et al.
Emergency Medicine: Concepts and Clinical Practice
. 4th ed. St. Louis, MO: Mosby-Year Book; 1999.
Samuels MA, Feske SK.
Office Practice of Neurology
. Philadelphia, PA: Churchill Livingstone; 2003.
Last Reviewed September 2011