Questions about symptoms, risk factors and medical history are important in making a diagnosis of encephalitis. Diagnostic tests that may be needed include the following:
May 15, 2014
Brain imaging. Brain imaging is often the first test if symptoms and patient history suggest the possibility of encephalitis. The images may reveal swelling of the brain or another condition that may be causing the symptoms, such as a tumor.
Technologies may include magnetic resonance imaging (MRI), which can produce detailed cross-sectional and 3-D images of the brain, or computerized tomography (CT), which produces cross-sectional images.
Spinal tap (lumbar puncture). With a spinal tap, the doctor inserts a needle into the lower back to extract cerebrospinal fluid (CSF), the protective fluid that surrounds the brain and spinal column. Changes in this fluid can indicate infection and inflammation in the brain.
In some cases, samples of CSF can be tested to identify the virus or other infectious agent.
- Other lab tests. Samples of blood or urine, or of excretions from the back of the throat can be tested for viruses or other infectious agents.
- Electroencephalogram (EEG). Your doctor may order an EEG, a test in which a series of electrodes are affixed to the scalp. The EEG records the electrical activity of the brain. Certain abnormal patterns in this activity may be consistent with a diagnosis of encephalitis.
- Brain biopsy. Rarely, a procedure to remove a small sample of brain tissue (brain biopsy) is used if symptoms are worsening and treatments are having no effect.
- Longo DL, et al. Harrison's Online. 18th ed. New York, N.Y.: The McGraw-Hill Companies; 2012. http://www.accessmedicine.com/resourceTOC.aspx?resourceID=4. Accessed Feb. 15, 2014.
- Encephalitis and meningitis fact sheet. National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/disorders/encephalitis_meningitis/detail_encephalitis_meningitis.htm. Accessed Feb. 17, 2014.
- Encephalitis. The Merck Manuals: The Merck Manual for Health Care Professionals. http://www.merckmanuals.com/professional/neurologic_disorders/brain_infections/encephalitis.html. Accessed Feb. 17, 2014.
- Hardarson HS. Acute viral encephalitis in children and adolescents: Clinical manifestations and diagnosis. http://www.uptodate.com/home. Accessed Feb. 15. 2014.
- Johnson RP, et al. Viral encephalitis in adults. http://www.uptodate.com/home. Accessed Feb. 15, 2014.
- Hardarson HS. Acute viral encephalitis in children and adolescents: Pathogenesis and etiology. http://www.uptodate.com/home. Accessed Feb. 15, 2014.
- Hardarson HS. Acute viral encephalitis in children and adolescents: Treatment and prevention. http://www.uptodate.com/home. Accessed Feb. 15, 2014.
- FAQ: Insect repellant use and safety. Centers for Disease Control and Prevention. http://www.cdc.gov/westnile/faq/repellent.html. Accessed Feb. 17, 2014.
- Insect repellent use and safety in children. U.S. Food and Drug Administration. http://www.fda.gov/Drugs/EmergencyPreparedness/ucm085277.htm. Accessed Feb. 17, 2014.
- Prevention & control. Centers for Disease Control and Prevention. http://www.cdc.gov/westnile/prevention/index.html. Accessed Feb. 17, 2014.
You Are ... The Campaign for Mayo Clinic
Mayo Clinic is a not-for-profit organization. Make a difference today.