Encephalitis

Encephalitis is inflammation of the brain, which is often caused by an infection or an autoimmune response. This can cause the tissue in the brain or spinal cord to swell, leading to seizures, problems with behavior and memory, and other symptoms.

There are two main types of encephalitis: infectious and autoimmune.

Infectious encephalitis

Viruses, bacteria, parasites, and even certain fungi can cause encephalitis.

These include:

• 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 symptoms of it.
• 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 viruses. These include West Nile virus, rabies, and Epstein-Barr virus.
• Lyme disease
• Toxoplasmosis
• Tuberculosis

Sometimes, the doctor 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, even if it’s not clear which specific virus is responsible.

Autoimmune encephalitis

Autoimmune encephalitis is a type of non-infectious encephalitis. In autoimmune encephalitis, the body’s immune system makes antibodies that attack healthy brain cells (neurons). Some types of autoimmune encephalitis that affect children include:

• Anti-NMDA receptor encephalitis 
• Limbic encephalitis
• Rasmussen syndrome
• MOG antibody disease
• Anti-GABA-A receptor encephalitis

The symptoms of encephalitis may depend on the part of the brain that is inflamed, the cause of the inflammation, the degree of inflammation, age, and other factors. Symptoms of encephalitis in children 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, symptoms may 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.
 

Brain inflammation can have different causes. It can occur in response to a bacterial or viral infection, or it can have an autoimmune cause, in which the body’s immune system attacks healthy tissues. However, a large number of encephalitis cases have no known cause.

The first step in treating your child is forming an accurate diagnosis. Their doctor will take a complete medical history of your child, including immunization history, and ask whether they have 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 used to diagnose encephalitis include:

• CT scan of the brain, to make sure that the symptoms aren’t caused by another cause
• Lumbar puncture (spinal tap) to take a small sample of spinal fluid to look for infections, like bacteria and viruses
• Electroencephalogram (EEG) to see if your child is having subtle underlying seizures
• Magnetic resonance imaging (MRI) to look at detailed images that can show inflammation in the brain
• Blood, urine, and stool tests to check for indications of infection

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).

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 (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 autoimmune cause, their 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, doctors focus on preventing related complications, often through medication, while your child's brain recovers from the inflammation.

At Boston Children’s Hospital, we care for children with encephalitis in our Neuroimmunology Center. Our team of pediatric neuroimmunologists takes a multidisciplinary approach, working with other specialists throughout Boston Children’s who have expertise in caring for children with encephalitis, including neurologists, immunologists, infectious disease experts, psychologists, physical therapists, education specialists, and others. Together, we will create a treatment plan that puts your family in the center.