Rasmussen Encephalitis
Rasmussen Encephalitis
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Author: Rachit Patil, MD

Brown University, Providence, Rhode Island 

Reviewed: May 2022


Rasmussen encephalitis (RE) is an inflammation of one half of the brain. RE is rare. It is also ongoing and progressive, meaning it gets worse over time. It usually occurs in children between six and ten years of age. However, there have been some cases in adolescents and adults.


Disorder Overview


In RE, a child develops seizures occurring in one half, or one region, of the brain. These are called focal onset seizures. Over months or years, these seizures negatively affect how well some parts of the brain can function. There are three stages of RE:

  • Prodromal stage. During this stage, a child experiences focal seizures intermittently. This means that the seizures are not frequent. The child often has no neurological problems.   
  • Acute stage. During this stage, the seizures often become more frequent. The affected side of the brain loses volume (it shrinks). This leads to problems with brain function in the region where the seizures originate. In addition to other neurological symptoms, it may result in: 
    • Weakness 
    • Vision changes 
    • Abnormal speech 
  • Residual stage. During this stage, there are fewer seizures. However, there is often significant shrinking in parts of the brain. This shrinking can lead to severe neurological problems.


Children are usually healthy before symptoms begin. Symptoms often start with three types of seizures:

Simple partial seizures (focal preserved awareness).

The patient remains aware of their surroundings.

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Complex partial seizures (focal impaired awareness).

The patient’s awareness is affected.

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Longer seizures (status epilepticus).

This often manifests as the condition epilepsia partialis continua. During this type of seizure, one part of the body twitches.

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Over the course of weeks or months, the seizures become difficult to treat. They often fail to respond to antiseizure medications. This is called drug-resistant epilepsy and other treatments, such as epilepsy surgery, may be considered.

Symptoms then progress to involve one half of the brain. This can lead to: 

  • Cognitive loss or learning difficulty 
  • Loss of vision on one side of each eye 
  • Weakness in the arms and legs on one side of the body 

Typically, symptoms are restricted to one side of the body. This is because only half of the brain is usually affected. If present, motor and vision problems will always occur on the side opposite to the affected side of the brain.  

Speech, language, and memory problems may arise if those functions are in the affected hemisphere. (For many people, these functions are primarily located in the left hemisphere.)  

Over time, the frequent seizures lead to a decline in: 

  • Academic abilities 
  • Other neurological functions 


The underlying cause of RE is unknown. However, it is under investigation by researchers.  

The inflammation of the brain in RE seems to be related to the body’s immune activity. The immune system usually works to keep us healthy.  

Sometimes, it functions abnormally, and attacks parts of our own body. This is called autoimmunity. A form of autoimmunity that has to do with T-cells is often linked to RE. However, the exact way this might lead to RE is unclear.

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A few things can help with an early diagnosis, including:

  • Clinical signs and symptoms 
  • A neurological exam 
  • A combination of diagnostic tests 

The following tests can be helpful in diagnosing RE: 

  • Electroencephalogram (EEG). Seizures are often the first sign of RE. So, an EEG can help reveal how the brain is slowing or causing seizures in a localized area, one region, or an entire side. The scope of the seizures can depend on the stage of the disease.  
  • Magnetic resonance imaging (MRI). A brain MRI at the beginning of the disease may be normal. However, a series of MRIs may be able to show atrophy, or shrinkage, of one side of the brain. This occurs as the condition gets more severe over time.  
  • Positron emission tomography (PET) scan. A PET scan may show that one side of the brain is no longer processing energy normally. 
  • Neuropsychological testing. Depending on the level of change in brain functioning, this testing may reveal problem areas around: 
    • Speech 
    • Behavior 
    • Motor function
    • Memory  


Identifying and diagnosing RE early is key for managing the disorder. There are several ways that RE can be managed. All treatment options must be discussed with a medical professional. 

Antiseizure Medication 

Seizures in RE can be managed with various antiseizure medications, often in combination. This may be key to controlling negative outcomes of the disorder.  

The medications that are best for controlling focal seizures should be used first or in combination with other antiseizure medication. A few common choices include: 

  • Oxcarbazepine 
  • Levetiracetam 
  • Lacosamide 

 Immunomodulatory Therapy 

Medicines that target the immune system are helpful in altering the way RE progresses. Some examples include: 

  • Steroids 
  • Intravenous immunoglobulins (IVIGs) 
  • Azathioprine 
  • Rituximab 

These can be tried in combination based on a plan made with the child’s neurologist.  


Epilepsy surgery is an option that should be considered with the consultation of the patient’s multidisciplinary team. Although surgery can have complications, it is often a successful treatment option. When performed early on, it can minimize the effect on the other hemisphere.  

Potential complications include:  

  • Bleeding 
  • Infection 
  • Loss of peripheral vision 
  • Weakness on the opposite side of the body  

If early surgical treatment is undertaken, it is possible for the brain to compensate for the loss of function on one half. It does so by making these connections on the normal side. For more information, please see the Brain Recovery Project.

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The outlook for patients with RE varies. There have been advances in recognizing and treating RE. However, there are no known treatments that can stop the progression of this condition.  

For a majority of children with RE, early surgery leads to a decrease in seizures. This may have beneficial impact on cognitive and functional outcome. However, even with surgery, many children still experience some degree of: 

  • Cognitive problems 
  • Problems with speech, walking, and more

Often, children with RE will need to take multiple antiseizure medications for years or for the rest of their lives. They may need frequent monitoring with EEGs and brain imaging. RE is often a lifelong disorder.


Pediatric Epilepsy Surgery Alliance
The Pediatric Epilepsy Surgery Alliance (formerly known as The Brain Recovery Project) enhances the lives of children who need neurosurgery to treat medication-resistant epilepsy. They empower families with research, support services, and impactful programs before, during, and after surgery. PESA’s programs include research-based, reliable information to help parents and caregivers understand when a child’s seizures are drug-resistant; the risks and dangers of seizures; the pros and cons of the various neurosurgeries to treat epilepsy; the medical, cognitive, and behavioral challenges a child may have throughout life; school, financial aid, and life care issues. PESA’s resources include a comprehensive website with downloadable guides, pre-recorded webinars, and virtual workshops; an informative YouTube channel with comprehensive information about epilepsy surgery and its effects; a private Facebook group (Education After Pediatric Epilepsy Surgery) with over 300 members; Power Hour (bi-monthly open forums and live virtual workshops on various topics); and free school training to help your child’s education team understand the impact of their epilepsy surgery in school. Their Peer Support Program will connect you with a parent who has been there. The Pediatric Epilepsy Surgery Alliance also hosts biennial family conferences and regional events that allow families to learn from experts, connect with other families, and form lifelong friendships. They also provide a travel scholarship of up to $1,000 to families in need to fund travel to a level 4 epilepsy center for a surgical evaluation.

In addition, PESA has resources for medical professionals to assist in helping clinicians help the parents of their patients find the resources they need after surgery. Educators and therapists will also find helpful resources and information, including videos, guides, and relevant research. Patients who have undergone surgery are encouraged to register with the Global Pediatric Epilepsy Surgery Registry to help set future research priorities.

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Child Neurology Foundation (CNF) solicits resources from the community to be included on this webpage through an application process. CNF reserves the right to remove entities at any time if information is deemed inappropriate or inconsistent with the mission, vision, and values of CNF. 


ClinicalTrials.gov for Rasmussen Encephalitis (birth to 17 years).

These are clinical trials that are recruiting or will be recruiting. Updates are made daily, so you are encouraged to check back frequently.   

ClinicalTrials.gov is a database of privately and publicly funded clinical studies conducted around the world. This is a resource provided by the U.S. National Library of Medicine (NLM), which is an institute within the National Institutes of Health (NIH). Listing a study does not mean it has been evaluated by the U.S. Federal Government. Please read the NLM disclaimer for details.    

Before participating in a study, you are encouraged to talk to your health care provider and learn about the risks and potential benefits.

The information in the CNF Child Neurology Disorder Directory is not intended to provide diagnosis, treatment, or medical advice and should not be considered a substitute for advice from a healthcare professional. Content provided is for informational purposes only.  CNF is not responsible for actions taken based on the information included on this webpage. Please consult with a physician or other healthcare professional regarding any medical or health related diagnosis or treatment options. 


Varadkar S, Bien CG, Kruse CA, Jensen FE, Bauer J, Pardo CA, Vincent A, Mathern GW, Cross JH. Rasmussen’s encephalitis: clinical features, pathobiology, and treatment advances. Lancet Neurol. 2014 Feb;13(2):195-205. https://doi.org/10.1016/S1474-4422(13)70260-6. PMID: 24457189; PMCID: PMC4005780.  

Fiorella DJ, Provenzale JM, Coleman RE, Crain BJ, Al-Sugair AA. (18)F-fluorodeoxyglucose positron emission tomography and MR imaging findings in Rasmussen encephalitis. AJNR Am J Neuroradiol. 2001 Aug;22(7):1291-9. PMID: 11498416; PMCID: PMC7975219.

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