Encephalitis is inflammation of the brain.

Causes

Most cases of encephalitis are caused by a viral infection. The most common viruses that cause encephalitis include:

• Viruses carried by mosquitoes

• Chickenpox virus

• Herpes simplex virus

• Polio virus

• Measles virus

• Mumps virus

• West Nile virus

• Rabies

Risk Factors

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

• Cancer

• Immunosuppressive medications after organ transplant

• AIDS

Symptoms

Symptoms include:

• Fever

• Weakness, severe fatigue

• Headache

• Sensitivity to light

• Stiff neck and back

• Vomiting

• Muscle aches

• Rash

• Personality changes

• Confusion

• Irritability

• Seizures

• Partial paralysis

• Trouble walking

• Trouble swallowing

Diagnosis

The doctor will ask about your symptoms and medical history, and perform 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 electrical activity in the brain

• Electroencephalogram (EEG) – to look for abnormal areas in the brain

• Brain Biopsy – removal of a small sample of brain tissue to test for signs of infection

Treatment

Treatment may include:

• Antiviral drugs (eg, intravenous acyclovir for herpes simplex encephalitis) to potentially help shorten the duration of the illness

• Steroid medications – to decrease brain swelling

• Anticonvulsant medications – to prevent and/or treat seizures

Prevention

Make sure that you and your children are vaccinated against preventable viral illnesses.

RESOURCES:

Encephalitis Information Resource
http://www.encephalitis.info

National Institute of Neurological Disorders and Stroke
http://www.ninds.nih.gov

References:

Cecil Textbook of Medicine. 21st ed. W.B. Saunders Company; 2000.

Conn's Current Therapy 2001. 53rd ed. W.B. Saunders Company; 2001.

Emergency Medicine: Concepts and Clinical Practice. 4th ed. Mosby-Year Book; 1998.

Principles and Practice of Infectious Diseases. 6th ed. Churchill Livingstone; 2005.