Encephalitis: Viral

Description

Treatment

With the exception of herpes simplex and varicella-zoster encephalitis, the viral forms of encephalitis are not treatable. The primary objective is to diagnose the patient as soon as possible in order to administer any medications that might treat the symptoms. It is imperative to lower fever and ease the pressure caused by swelling of the brain.

Addressing Possible Life-Threatening Complications

Patients with very severe encephalitis are at risk for systemic (body wide) complications including shock, low oxygen, low blood pressure, and low sodium levels. Any potentially life-threatening complication should be addressed immediately with the appropriate treatments.

Treating Probable Causes of Encephalitis

Since it is difficult to determine the cause of encephalitis, and since rapid treatment is essential, it is common to medicate the patient for the causes that respond to medication without waiting to determine the cause of the illness:

• Some experts advise immediately administering intravenous acyclovir, the standard treatment for herpes simplex encephalitis, to all patients whose symptoms indicate encephalitis.
• Corticosteroids, which reduce inflammation, may also be administered immediately.
• Antibiotics, which attack bacteria but not viruses, are used in case the cause of the symptoms is bacterial meningitis.

Supportive Treatments

For any form of encephalitis, treatments are aimed at reducing symptoms:

• Seizures may be prevented using fosphenytoin (Cerebyx). If they develop, they can be treated with intravenous lorazepam (Ativan).
• Sedatives may be prescribed for irritability or restlessness.
• Simple pain relievers may be used for fever and headache.

In patients who are otherwise stable, the only other treatment measures are to keep the head elevated and monitor the patients status.

Treatments for Herpes Virus Encephalitis

Intravenous acyclovir is the treatment of choice for encephalitis caused by herpes simplex virus or varicella-zoster virus. Treatment must be initiated within two days of symptoms for the best outcome. In nearly all cases, the virus clears within two weeks of treatment. If there is still evidence of its presence, medications are continued for another two weeks. In rare cases, surgical measures may be needed to relieve the buildup of pressure in the brain.

Acyclovir is nearly always administered in the hospital. Some centers are finding that some patients can be safely treated with intravenous medications at home after the first few days, although close monitoring by a health professional is essential.

Of concern is a relapse rate of about 25% in patients who have been successfully treated for herpes encephalitis. Early diagnosis and treatment may help reduce this risk. A study is underway to determine if a three-month course of oral valacyclovir will improve remission rates after a patient completes treatment with intravenous acyclovir. Foscarnet (Foscavir) is another powerful antiviral agent known as a pyrophosphate analogue, which may be useful for herpes simplex viral strains that have become resistant to acyclovir.

Investigative Treatments for West Nile Virus and Other Arboviruses

There are no drugs that have been effective for treating arboviruses, including West Nile Virus. A number of agents used to treat other virus infections are being investigated. They include ribavirin (an antiviral agent used to treat influenza), interferon alfa 2a (Roferon-A) and other interferons, and glycyrrhizin (a compound in licorice root with anti-viral activity).

Treatment for Acute Disseminated Encephalomyelitis (ADEM)

ADEM is usually treated with high-dose intravenous methylprednisolone, a corticosteroid. This agent is a powerful anti-inflammatory drug. Intravenous immunoglobulin (IVIG), alone or in combination with methylprednisolone, is also showing promise in certain patients, including children with severe ADEM.

If the body requires an increase in oxygen, the kidney produces more of the hormone erythropoietin (EPO), which acts in the bone marrow to increase the production of red blood cells. A genetically engineered version of the hormone, called recombinant erythropoietin epoetin alfa (Epogen, Procrit, AraNESP) is used in many disorders requiring an increase in red blood cells. Some evidence suggests that it also helps protect the brain. Experimental work suggests it may be helpful for ADEM patients. It is very safe and warrants investigation in other forms of encephalitis as well.