Viral Encephalitis Treatment & Management

Medical care should be devoted to appropriate management of the airway, bladder function, fluid and electrolyte balance, nutrition, prevention of bedsores, secondary pulmonary infection, and hyperpyrexia. A multidisciplinary approach must be instituted as early as possible to start physical and cognitive rehabilitation and to minimize cognitive problems and long-term sequelae. Care in an intensive care unit (ICU) setting may be required, especially if seizure activity or increased intracranial pressure (ICP) is present.^[35]

Delayed diagnosis of herpes simplex encephalitis (HSE) increases morbidity and mortality rates; failure to diagnose and treat early could result in litigation. With the wide availability of effective therapy, initiating antiviral treatment before a definitive diagnosis of HSE encephalitis (ie, during the workup) is now common practice.

The use of corticosteroids as an adjunctive therapy for viral encephalitis is controversial and currently being evaluated in a large clinical trial.

See the following for complete information on these topics:

• Herpes Simplex Encephalitis
• California Encephalitis
• Eastern Equine Encephalitis
• Japanese Encephalitis
• St Louis Encephalitis
• Venezuelan Encephalitis
• Western Equine Encephalitis
• West Nile Encephalitis

Pharmacotherapy for HSE consists of acyclovir and vidarabine. Outcome is improved with either agent, but acyclovir is more effective and less toxic. Even if the final diagnosis of HSE has not been established, intravenous (IV) acyclovir should be initiated immediately. Acyclovir is also the drug of choice for varicella-zoster virus (VZV) encephalitis, although ganciclovir is also considered an alternative option.

Ganciclovir has been used for cytomegalovirus (CMV) encephalitis, but with therapeutic failures; consequently, the optimal therapy for CMV encephalitis is unknown. Ganciclovir combined with foscarnet has been used in the treatment of patients infected with HIV.

No specific treatment is available for the arbovirus encephalitides. Ribavirin seems to be effective for Lassa fever; its efficacy in other viral infections is being evaluated. Intraventricular ribavirin has been associated with clinical improvement in 4 patients with subacute sclerosing panencephalitis (SSPE) and apparently reduced mortality in an open-label trial in patients with Nipah virus encephalitis.

Results from a small series suggested that interferon alfa-2b reduced the severity and duration of the complications of St Louis encephalitis virus meningoencephalitis.^[36]

Because specific therapy for encephalitis is limited and because potentially serious sequelae (or death) may result from HSE, early treatment with acyclovir should be started as soon as possible in all patients with suspected viral encephalitis, pending the results of diagnostic studies. Once an etiologic agent of the encephalitis is eventually identified, therapy should be targeted to that agent (if available).

Other antibacterial treatments (eg, for bacterial meningitis) should be administered on the basis of epidemiological and clinical factors or given until the diagnosis of bacterial meningitis is excluded. Doxycycline should be added if there is suspicion of rickettsial or ehrlichial infection during the appropriate season.

Increased ICP should be managed in the ICU setting with head elevation, gentle diuresis, mannitol, and hyperventilation. Surgical decompression may be necessary if there is impending uncal herniation or increased ICP that is refractory to medical management. Controlled studies are lacking, but there is some evidence that patients with life-threatening cerebral edema may benefit from craniectomy or other approaches to lower the increased ICP in neurocritical care units.^[37]

Encephalitis causes a wide range of behavioral manifestations with limbic and frontal syndromes that can be difficult to distinguish from partial seizures.^[38] Seizure activity can be closely observed using electroencephalography (EEG), and the threshold for administering temporary anticonvulsant therapy should be low.

Phenytoin and valproic acid can be administered intravenously. Phenytoin and carbamazepine can be administered when oral or intragastric drug administration is possible. Benzodiazepines are also important when used to abort status epilepticus.

If seizure activity persists after the acute phase, patients may need long-term anticonvulsant therapy. Accordingly, additional therapy may be necessary for extrapyramidal, motor, and behavioral complications.

Surveillance is important to predict outbreaks of arboviral infections. Mosquitoes can be sampled to estimate infection rates in mosquito pools. Protective clothing and repellents are useful in the prevention of arthropod bites. Avoidance of outdoor activities is also useful. Prompt removal of ticks may decrease the risk of transmission of a tick-borne virus.

Effective preventive measures include removing water-holding containers and discarded tires. Insecticides may be useful in the emergency control of infected mosquitoes. Control of the mosquito vector has been used with apparently good results in several recent epidemics.

Vaccines are available for eastern equine encephalitis (EEE), western equine encephalitis (WEE), and Venezuelan equine encephalitis (VEE) in horses. A live attenuated vaccine (TC-83) has been used to protect laboratory and field workers from the virus that causes VEE. Vaccines have also been developed for Japanese B virus encephalitis (JE) and tick-borne encephalitis.

Killed virus vaccines have been produced experimentally for several arboviruses. A live-attenuated Japanese B vaccine (SA 14-14-2) has been used widely in Asia. Since 1989, 120 million children have been immunized, and a recent report has demonstrated the efficacy of a single dose in preventing Japanese encephalitis (JE) when administered only days or weeks before exposure to infection. The only internationally licensed JE virus vaccine is a formalin-inactivated vaccine.

Limited use (eg, in exposed laboratory workers) has been made of vaccines for VEE and tick-borne viral encephalitis. Passive immunization of laboratory workers exposed to a known virus in a laboratory accident has been accomplished with immune (human) serum or gamma globulin.

Despite control efforts and disease surveillance, the 1999 outbreak of West Nile virus in New York, with subsequent spread to other states in the United States, showed that different viruses may be spread in the Western hemisphere because of increased international travel and trade. Massive culling of pigs in Malaysia decreased the incidence of Nipah virus infection.

Encephalitis is a neurological emergency. Consultation with a neurologist is recommended. Consultation with a neurosurgeon is helpful if a brain biopsy is considered. Consultation with an infectious disease specialist is also appropriate.

Given the high likelihood of long-term need for cognitive rehabilitation and physical rehabilitation, especially in moderately severe and severe forms of encephalitis, establishing a multidisciplinary approach early in the disease course is appropriate. A multidisciplinary approach includes consultations with physical, occupational, and speech therapists.

No dietary restrictions are necessary. The infectious process, especially with the presence of fever, increases nutritional requirements. Early assessment by a speech therapist and a dietitian helps prevent further body wasting and detects early behavioral manifestations that prevent adequate nutritional intake, such as placidity, apraxia, dysphagia, or agitation.