Encephalitis

Encephalitis is inflammation of the brain, caused by an infection. The infection may be bacterial or viral. In some cases, encephalitis may be the result of an immune system disorder. When inflammation is caused by an infection in the brain, it's known as infectious encephalitis. And when it's caused by your own immune system attacking the brain, it's known as autoimmune encephalitis. Sometimes there is no known cause.

In some cases, encephalitis can be life-threatening. Prompt diagnosis and treatment are important because it's difficult to predict how encephalitis will affect each individual.

## Symptoms

Encephalitis may cause many different symptoms including confusion, personality changes, seizures or problems with movement. Encephalitis also may cause changes in sight or hearing. The symptoms of encephalitis include:

* Fever and chills
* Headaches
* Nausea and vomiting
* Loss of appetite
* Fatigue and weakness
* Tiredness
* Sore throat
* Seizures
* Dizziness, lightheadedness, or vertigo
* Cough
* Sneezing
* Sweating
* Aches in muscles or joints
* Stiff neck
* Confusion, memory loss, slurred speech, trouble speaking, and trouble understanding
* Numbness and weakness of the arms and legs
* Numbness, tingling, or paralysis of one side of the body
* Blindness in one or both eyes
* Deafness in one or both ears
* Problems with attention, balance, and coordination
* Fainting
* Muscle weakness
* Loss of consciousness
* Coma

## Causes

The 2 causes of encephalitis include:

* **Infectious encephalitis.** This condition occurs when a virus or other agent directly infects the brain. The infection may affect one area or be widespread. Viruses are the most common causes of infectious encephalitis, including some that can be passed by mosquitoes or ticks. Very rarely, encephalitis may be caused by bacteria, fungus or parasites.
* **Autoimmune encephalitis.** This condition occurs when your own immune cells mistakenly attack the brain or make antibodies targeting proteins and receptors in the brain. The exact reason why this happens is not completely understood. Sometimes the abnormal immune response can be triggered by benign or cancerous tumors, known as paraneoplastic and autoimmune encephalitis. Other types of autoimmune encephalitis such as acute disseminated encephalomyelitis (ADEM) can be triggered by infection in your body. This is known as post-infectious autoimmune encephalitis. In many instances, no definitive trigger for the abnormal immune response is identified.

## Treatment

Treatment for mild encephalitis usually consists of:

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

### Antiviral medicines

Encephalitis caused by certain viruses usually requires antiviral treatment.

Antiviral medicines commonly used to treat encephalitis include:

* Acyclovir (Zovirax).
* Ganciclovir (Zirgan).
* 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, health care providers often recommend immediate treatment with acyclovir. Acyclovir can be effective against HSV, which can result in significant complications when not treated promptly.

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

### Autoimmune encephalitis

If the tests show an autoimmune cause of encephalitis, then medicines that target your immune system, known as immunomodulatory medicines, or other treatments may be started. These may include:

* Intravenous or oral corticosteroids.
* Intravenous immunoglobulin.
* Plasma exchange.

Some people with autoimmune encephalitis need long-term treatment with immunosuppressive medicines. These may include azathioprine (Imuran, Azasan), mycophenolate mofetil (CellCept), rituximab (Rituxan) or tocilizumab (Actemra).

Autoimmune encephalitis caused by tumors may require treatment of those tumors. This may include surgery, radiation, chemotherapy or a combination of treatments.

### 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 medicines, such as corticosteroids, to reduce swelling and pressure within the skull.
* Anticonvulsant medicines, 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:

* **Brain rehabilitation** to improve cognition and memory.
* **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.