Encephalitis: Viral - Risk Factors

Prognosis

In most cases of arbovirus infection, symptoms are mild, last 3 - 5 days, and resolve without becoming serious. In fact, the infection is generally unrecognized as anything other than a mild flu.

Prognosis for Severe Encephalitis

Prognosis for severe encephalitis depends on many factors, including:

• Age of the patient -- worse outcomes for infants under age 12 months and adults over age 55
• Immune status
• Preexisting neurological conditions
• Virulence of the virus

Death from Suppression of Vital Functions

In severe cases of encephalitis, the swelling of the brain inside the skull places downward pressure on the brain stem. The brain stem controls vital functions, such as respiration and heartbeat, and if the pressure becomes too severe, these vital functions can cease and cause death.

---

---

Complications from Brain Damage

Survivors of encephalitis commonly experience neurologic consequences, which can be long-term and even permanent. The degree and type of brain damage can vary from mild-to-severe and from focal (in one part of the brain) to multifocal (several parts of the brain) to diffuse (throughout the brain).

While coma can occur in patients with severe encephalitis, it does not necessarily predict a fatal or severe outcome. Some patients experience no or mild-to-moderate complications after awakening from an encephalitis-associated coma.

The location and severity of the infection largely determines the pattern of brain damage and therefore its effects, which can be:

• Physical (muscle control)
• Behavioral and emotional (personality changes)
• Cognitive (memory, speech)
• Sensory (vision, hearing)

Review Date: 01/26/2011
Reviewed By: Harvey Simon, MD, Editor-in-Chief, Associate Professor of Medicine, Harvard Medical School; Physician, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.

A.D.A.M., Inc. is accredited by URAC, also known as the American Accreditation HealthCare Commission (www.urac.org).