An Overview of Rasmussen's Encephalitis

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Rasmussen's encephalitis, which sometimes is referred to as Rasmussen's syndrome, is a chronic neurological disorder characterized by inflammation of one side of the brain that causes seizures that are difficult to control. It can lead to progressive neurological deficits. Rasmussen's encephalitis is rare. The disorder usually becomes apparent before age 10.

Symptoms of Rasmussen's Syndrome
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The symptoms of Rasmussen's encephalitis include:

  • Seizures that often predominantly affect one side of the body
  • Weakness, usually on one side of the body
  • Language problems if the dominant hemisphere is affected (usually the left)
  • Cognitive deficits (thinking and problem-solving difficulties)

Generally, the seizures caused by Rasmussen's encephalitis are difficult to control with medication. They usually are focal, with shaking and jerking of one side of the body. They may progress to the point at which they're nearly continuous, which is referred to as epilepsia partialis continua.

Weakness, language problems, and cognitive difficulties often start to occur months after seizures begin and can become severe.


This condition most commonly affects children ages 2 to 12, but can affect people of any age. While it's unclear what the exact cause of Rasmussen’s encephalitis is, the medical community has considered two main possibilities:

  • An infection that triggers a severe immune reaction
  • An autoimmune reaction (the body attacking itself)

As researchers have learned more about this disease, they've found compelling evidence to back up the autoimmune theory. At the very least, research appears to show that Rasmussen's involves at least some autoimmune activity, with specialized immune cells invading and attacking one side of the brain.


It may take a long time to get a definitive diagnosis of Rasmussen's encephalitis. This is because there is no simple test to confirm it. Rather, the disorder is diagnosed based on a healthcare provider’s observations of clinical symptoms over months (or even years), as well as with electroencephalogram (EEG) and brain magnetic resonance imaging (MRI) testing.

An EEG is expected to show seizure activity on one side of the brain. But this EEG pattern is not unique to Rasmussen’s encephalitis, so the test is not definitive. Results are considered in conjunction with your symptoms, other tests, and your healthcare provider’s observations of your condition.

A brain MRI is expected to show a significant difference between the two sides of the brain. Early in the course of the illness, one side of the brain may show an inflammatory pattern.

Later in the course of the illness, the brain MRI may show atrophy of the affected side, which is actually shrinking of the brain due to prolonged damage from inflammation. This brain MRI appearance is not unique to Rasmussen’s encephalitis either, so this, too, will be considered along with other factors in order to reach a formal diagnosis.


There is no cure for Rasmussen's encephalitis. The main treatment option is anti-seizure medication. Sometimes, steroids and other immunological therapies are used to try to decrease the inflammation in the brain.

If you have seizures, weakness, or any other neurological deficit but no evidence of inflammation, then your treatment is largely going to target your seizures and neurological deficit.

Sometimes the epilepsy of Rasmussen’s encephalitis is so severe that surgery is required. This surgery could involve removing the affected region of the brain, especially if that region appears to be causing much of the damage.

Often, the surgical procedure causes lasting side effects, such as partial or complete weakness of one side of the body.

Surgical intervention for Rasmussen’s encephalitis should be very carefully deliberated, and it is only an option if it is expected to improve your overall quality of life.


Dealing with Rasmussen's encephalitis can be challenging, especially for a parent. Reach out to your child's school to see what support and resources may be available. Let them know about any cognitive changes your child may be undergoing and make sure the staff knows how to handle a seizure if one should happen at school.

A support group can be a big help, as well. You may be able to get advice and learn through shared experiences. Plus, it can help just to know other people understand what you're going through.

This disease, especially in a child, can impact the entire family. If you're having trouble dealing with any aspect of it, don't hesitate to see a mental health counselor.

A Word From Verywell

When all you want is to keep something from getting worse and for things to be back to normal, it can be difficult to hear healthcare providers tell you that's not possible. The best things you can do to feel more empowered is to educate yourself about the disease and to try to have realistic expectations about treating and managing it.

8 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
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Additional Reading

By Heidi Moawad, MD
Heidi Moawad is a neurologist and expert in the field of brain health and neurological disorders. Dr. Moawad regularly writes and edits health and career content for medical books and publications.