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What is encephalitis?

Encephalitis simply means that the brain tissues have become inflamed. When brain tissues are inflamed, they don’t work properly, which is why your child may experience seizures, mental confusion or changes in behavior.

Infection or inflammation in the brain can lead to permanent damage. Unfortunately, there’s no way to predict the long-term effects of encephalitis. Some children have lots of serious symptoms but respond very well to treatment; others have milder cases but have epilepsy and more long-term learning issues.

Why is encephalitis hard to diagnose?

Encephalitis can be hard to diagnose because it’s a reaction to something, in the same way that a bruise is a reaction to an injury. Often, we may find a bruise and not know what caused it; the same is true for encephalitis.

Another reason is that the absolute best way to determine what causes encephalitis is a brain biopsy. But since this is an extremely invasive procedure, it’s usually only used in very severe cases. Instead, we do other tests, such as a spinal tap, which may or may not pick up on a virus in a brain cell.

Can encephalitis be prevented?

Some forms of encephalitis are transmitted through mosquito bites, and we can prevent those forms by preventing mosquito bites. You and your child can help protect yourselves from mosquito bites by:

  • wearing long sleeves, long pants and socks when outside
  • using bug spray
  • wearing light-colored clothing (mosquitoes are attracted to darker colors)
  • avoiding areas of standing water, like ponds, wells and birdbaths (this is where mosquitos lay their eggs)

There’s a lot of information on the Internet about encephalitis—much of it misleading. People often hear "encephalitis" and think virus—particularly West Nile virus. But encephalitis (inflammation of the brain) actually has a wide range of causes, levels of severity, treatment options and outcomes.

Encephalitis is a rare neurological condition that often comes on suddenly. Encephalitis means that brain tissues have become inflamed. When brain tissues are inflamed it can cause your child to have seizures, mental confusion or changes in behavior.

  • Cases of encephalitis can range from mild to severe, with a range of physical, behavioral and neurological outcomes.
  • It may take several months for the full effects of a child’s encephalitis to become clear.
  • Some children respond very well to treatment; others have epilepsy and long-term school or learning issues.
  • Although encephalitis can be life-threatening in its most severe form, this is rare.
  • Physical, speech, and occupational therapy can be very helpful in helping your child recover from encephalitis.

How we care for encephalitis

Boston Children’s Pediatric Neuro-immunology Program is dedicated to the comprehensive care of children, adolescents and families who are affected by encephalitis. Our team includes pediatric neurologists and neuropsychologists, and we consult with pediatric specialists in rheumatology, infectious diseases and epilepsy when it’s beneficial.

Here, your child benefits from the expertise of a main referral center for pediatric encephalitis in New England. We also have strong ties to the small network of physicians and researchers all over the country who are working to better understand, diagnose and treat this extremely rare condition.

Our program is part of the Department of Neurology at Boston Children's, the oldest and largest program in pediatric neurology in the world.

Encephalitis | Symptoms & Causes

What are the symptoms of encephalitis?

Your child’s symptoms may depend on the situation — the part of the brain that is inflamed, the cause of the inflammation, the degree of inflammation, age, and other medical problems. But even children in the same situation may show symptoms differently. Some of the most common symptoms of encephalitis may include:

  • fever
  • headache
  • sensitivity to light
  • neck stiffness
  • skin rashes
  • nausea/vomiting
  • loss of energy/appetite
  • changes in alertness (sleepiness)
  • confusion or hallucinations
  • difficulty talking
  • problems walking
  • seizures

Since encephalitis is often caused by a virus, you may notice symptoms appear alongside or following other symptoms of a virus, such as an upper respiratory infection (like a cold, sore throat), or a gastrointestinal problem like diarrhea, nausea, vomiting, or rash.

What causes encephalitis?

Encephalitis means that the brain tissue has become inflamed, and this can be caused by different things:

  • It can be the normal (and healthy) reaction of the body to a viral or bacterial infection.
  • It can be the immune system over-reacting to an infection that might not even be still present in the body.
  • It can have an autoimmune cause (the body’s immune cells become confused and start to attack healthy tissue) and occur without an infection of any kind.

Where you live might also play a role. For example, in New England, the West Nile virus is the most common mosquito-born viral cause of encephalitis.

Viruses and other infectious agents

There are some viruses that we know can cause encephalitis:

  • Herpes simplex virus: This is a common cause of encephalitis. Most children have been exposed to this virus, and your child may be infected with it even if they do not have a cold sore or blister around their mouth, or other sign of the virus.
  • Enteroviruses: These viruses enter the body through the gastrointestinal tract and can also cause hand-foot-mouth disease.
  • Measles, mumps, rubella, and chickenpox viruses: Keeping your child up-to-date with their vaccinations greatly lowers the rate of encephalitis from these viruses.

Other times, we may find signs in your child’s blood or spinal fluid (such as an increased white blood cell count) that their body is battling a virus or other infection that may be causing the encephalitis, even if we don’t know which particular one it is.

Encephalitis can also occur following infection by agents carrying diseases, including ticks (Lyme disease), mosquitos (West Nile virus), and cats (Bartonella, otherwise known as cat-scratch disease), or other animal exposures, environmental exposure such as swimming in fresh-water bodies, or travel to certain regions.

Non-infectious causes

In the past, physicians assumed that if we couldn’t identify the cause of a case of encephalitis, the cause must be a virus that we weren’t able to detect. But now we recognize that encephalitis can also be caused by over-activity of your child’s immune system in a way that may not have been triggered by a virus.

It’s important to remember that the severity of symptoms has nothing to do with the cause, and two people might have equally severe cases of encephalitis caused by different factors.

Encephalitis | Diagnosis & Treatment

How is encephalitis diagnosed?

The first step in treating your child is forming an accurate diagnosis. Your doctor will take a complete medical history of your child, including immunization history, and ask whether they has been involved in any activities or been anywhere where they may have been exposed to viruses known to cause encephalitis. Your child’s doctor may also ask if your child has recently:

  • had a cold or other respiratory illness, or a gastrointestinal illness
  • had a tick bite
  • been around pets or other animals
  • traveled to certain areas of the country or outside of the country

This information can provide clues as to what might be causing your child’s symptoms. Some of the procedures we use to diagnose encephalitis include:

In extremely rare cases, your doctor may recommend taking a sample of your child’s inflamed brain tissue through a small biopsy. The sample will be studied under the microscope by a pathologist to see whether the underlying cause can be found and this may help guide treatment decisions for your child.

What are the treatment options for encephalitis?

The key to treating encephalitis is early detection and treatment. Most children who are diagnosed with encephalitis are hospitalized for two weeks to a month, and sometimes children with severe cases spend time in the intensive care unit (ICU).

The first step in caring for your child is to stabilize their medical condition and try to figure out what caused the condition. Your child's doctor may order a lumbar puncture to look for evidence of bacteria and viruses.

While your child's team is working to determine the cause of the encephalitis, they'll be treated for two to three days with intravenous (through an IV) medications to fight certain bacteria and the herpes simplex virus, while awaiting lab results, as a precautionary measure.

If your child's encephalitis has an auto-immune cause, your doctor will talk with you about treating them with a course of immunosuppressants (these may include high-dose steroids, intravenous antibodies, or plasmapheresis, a process that filters your child's blood). While most children with this type of encephalitis only need a single course of immunosuppressants, some children may need to stay on them for a longer period of time.

Unfortunately, there often isn't a cause that can be pinpointed and treated. In these cases, we focus on preventing related complications, often through medication, while your child's brain recovers from the inflammation.

Encephalitis | Programs & Services