Diagnosis

Your doctor will start with a thorough physical examination and medical history.

Your doctor might then recommend:

  • Brain imaging. MRI or CT images can reveal any swelling of the brain or another condition that might be causing your symptoms, such as a tumor.
  • Spinal tap (lumbar puncture). A needle inserted into your lower back removes 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. Sometimes samples of CSF can be tested to identify the virus or other infectious agent.
  • Other lab tests. Samples of blood, urine or excretions from the back of the throat can be tested for viruses or other infectious agents.
  • Electroencephalogram (EEG). Electrodes affixed to your scalp record the brain's electrical activity. Certain abnormal patterns may indicate a diagnosis of encephalitis.
  • Brain biopsy. Rarely, a small sample of brain tissue might be removed for testing. Brain biopsy is usually done only if symptoms are worsening and treatments are having no effect.

Treatment

Treatment for mild encephalitis usually consists of:

  • Bed rest
  • Plenty of fluids
  • Anti-inflammatory drugs — such as acetaminophen (Tylenol, others), ibuprofen (Advil, Motrin IB, others) and naproxen sodium (Aleve) — to relieve headaches and fever

Antiviral drugs

Encephalitis caused by certain viruses usually requires antiviral treatment.

Antiviral medications commonly used to treat encephalitis include:

  • Acyclovir (Zovirax)
  • Ganciclovir (Cytovene)
  • Foscarnet (Foscavir)

Some viruses, such as insect-borne viruses, don't respond to these treatments. But because the specific virus may not be identified immediately or at all, doctors often recommend immediate treatment with acyclovir. Acyclovir can be effective against HSV, which can result in significant complications when not treated promptly.

Antiviral medications are generally well-tolerated. Rarely, side effects can include kidney damage.

Supportive care

People who are hospitalized with severe encephalitis might need:

  • Breathing assistance, as well as careful monitoring of breathing and heart function
  • Intravenous fluids to ensure proper hydration and levels of essential minerals
  • Anti-inflammatory drugs, such as corticosteroids, to reduce swelling and pressure within the skull
  • Anticonvulsant medications, such as phenytoin (Dilantin), to stop or prevent seizures

Follow-up therapy

If you experience complications of encephalitis, you might need additional therapy, such as:

  • Physical therapy to improve strength, flexibility, balance, motor coordination and mobility
  • Occupational therapy to develop everyday skills and to use adaptive products that help with everyday activities
  • Speech therapy to relearn muscle control and coordination to produce speech
  • Psychotherapy to learn coping strategies and new behavioral skills to improve mood disorders or address personality changes

Preparing for your appointment

Serious illness associated with encephalitis is usually severe and relatively sudden, so seek emergency care. The emergency care team will likely include specialists in infectious diseases and in the brain and nervous system (neurologist).

Questions from your doctor

You may need to answer these questions, or answer them on behalf of your child or another person with severe illness:

  • When did the symptoms begin?
  • Have you recently started taking any new medications? If so, what is the medication?
  • Have you been bitten by a mosquito or tick during the past few weeks?
  • Have you traveled recently? Where?
  • Have you recently had a cold, flu or other illness?
  • Are you up to date on your immunizations? When was your last one?
  • Have you had any exposure to wild animals or known toxins recently?
  • Have you had unprotected sex with a new or long-term sexual partner?
  • Do you have a condition or take any medications that result in a weakened immune system?

Encephalitis care at Mayo Clinic

June 13, 2017
References
  1. Bennett JE, et al. Encephalitis. In: Mandell, Douglas, and Bennett's Principles and Practice of Infectious Diseases. 8th ed. Philadelphia, Pa.: Saunders Elsevier; 2015. http://www.clinicalkey.com. Accessed Jan. 24, 2017.
  2. Hardarson HS. Acute viral encephalitis in children: Clinical manifestations and diagnosis. http://www.uptodate.com/home. Accessed Jan. 31, 2017.
  3. Ferri FF. Encephalitis, acute viral. In: Ferri's Clinical Advisor 2017. Philadelphia, Pa.: Elsevier; 2017. http://www.clinicalkey.com. Accessed Jan. 24, 2017.
  4. AskMayoExpert. Viral encephalitis. Rochester, Minn.: Mayo Foundation for Medical Education and Research; 2016.
  5. Gluckman SJ. Viral encephalitis in adults. http://www.uptodate.com/home. Accessed Jan. 24, 2017.
  6. Meningitis and encephalitis fact sheet. National Institute of Neurological Disorders and Stroke. https://www.ninds.nih.gov/Disorders/Patient-Caregiver-Education/Fact-Sheets/Meningitis-and-Encephalitis-Fact-Sheet. Accessed Feb. 1, 2017.
  7. Dorsett M, et al. Diagnosis and treatment of central nervous system infections in the emergency department. Emergency Medical Clinics of North America. 2016;34:917.
  8. Patel H, et al. Long-term sequelae of West Nile virus-related illness: A systematic review. The Lancet Infections Diseases. 2015;15:951.
  9. Hardarson HS. Acute viral encephalitis in children: Treatment and prevention. http://www.uptodate.com/home. Accessed Jan. 31, 2017.
  10. Daroff RB, et al. Viral encephalitis and meningitis. In: Bradley's Neurology in Clinical Practice. 7th ed. Philadelphia, Pa.: Saunders Elsevier; 2016. https://www.clinicalkey.com. Accessed Feb. 1, 2017.
  11. Zachary KC. Acyclovir: An overview. http://www.uptodate.com/home. Accessed Feb. 1, 2017.
  12. Breisch N. Prevention of arthropod and insect bites: Repellents and other measures. http://www.uptodate.com/home. Accessed Jan. 31, 2017.
  13. West Nile virus FAQ: Insect repellant use and safety. Centers for Disease Control and Prevention. http://www.cdc.gov/westnile/faq/repellent.html. Accessed Feb. 1, 2017.
  14. West Nile virus: Prevention & control. Centers for Disease Control and Prevention. http://www.cdc.gov/westnile/prevention/index.html. Accessed Feb. 1, 2017.
  15. Riggin EA. Allscripts EPSi. Mayo Clinic, Rochester, Minn. Jan. 24, 2017.
  16. Howe CL, et al. Neuroprotection mediated by inhibition of calpain during acute viral encephalitis. Scientific Reports. 2016;6:28699.
  17. Singh TD, et al. Predictors of outcome in HSV encephalitis. Journal of Neurology. 2016;263:277.
  18. Wormser GP, et al. Update and commentary on four emerging tick-borne infections. Infectious Disease Clinics of North America. 2015;29:371.