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Rasmussen syndrome

This is a very rare form of brain malfunction which may happen at any time during childhood. It most commonly affects children aged 3 to 11 years. It may rarely happen in children less than 3 years of age, or in adulthood. It is not known what causes the problem. But what is known is that brain cells in one part of one hemisphere (half) of the brain become very inflamed and also swollen.

The cause of the inflammation is not known. There is no evidence of a viral infection in the majority of cases, although research has shown that very occasionally a virus may be present. It is possible that a virus may trigger an antibody response in the brain – which then causes the inflammation and malfunction of the brain. This is called an ‘auto-immune’ condition, in which the body’s antibodies can actually damage one or more organs in the body. In Rasmussen syndrome, the damaged organ is the brain.


The result of the inflammation is that nerve cells malfunction, and this causes seizures. To begin with the seizures may be infrequent but then after some weeks or months the seizures occur very frequently, often many times a day. The seizures are usually focal (partial). They can also become continuous. This is called ‘epilepsia partialis continua’.

The most commonly affected parts of the brain are the frontal lobe and the temporal lobes. One of the motor (movement) control centres in the brain lies in the back part of the frontal lobe. Because of this, many of the seizures involve focal motor seizures. These cause rhythmical jerking of the arm and/or leg on the opposite side of the body. The seizures are usually very difficult to control with medicines.

After a variable period of time - from months to years - the child will then usually develop a weakness of the side of the body that is affected by the seizures. This weakness is called a ‘hemiparesis’ or ‘hemiplegia’. As the seizures continue, this weakness worsens. Some children may also develop learning or behaviour problems as the condition progresses. This can be as a result of the underlying progressive nature of the disorder, the number of seizures they have, side-effects of medicines, or a combination of all 3. 


All investigations are usually normal, except for the EEG and brain scans. Everyone has electrical activity happening in their brain. The EEG is used to record this electrical activity. When Rasmussen syndrome has been present for some months, the EEG will usually show a typical pattern called periodic lateralising epileptiform discharges (PLEDs). PLEDs is almost continuous abnormal electrical activity which involves the whole of the affected hemisphere. Brain scans, particularly the magnetic resonance imaging (MRI) scan, will become abnormal within a number of months of the condition starting. The MRI usually shows evidence of irreversible damage to nerve cells caused by the inflammation. This damage shows itself as shrinkage of the brain and particularly the part of the brain called the ‘grey matter’. This shrinkage is known as atrophy.


Seizures in Rasmussen syndrome can be difficult to treat. There is no particular epilepsy medicine that seems to be more effective than another. Commonly used epilepsy medicines include carbamazepine, levetiracetam, topiramate and clobazam. Medicines to suppress or alter the immune system may also be used. These include steroids, azathioprine and immunoglobulins (also called gammaglobulins). These medicines may have to be given intravenously (through a ‘drip’) every few months. The ketogenic diet is not usually helpful.

For some young people, the disorder is confined to a part of the brain that can be safely removed, particularly the temporal lobe. Occasionally, the whole of one side of the brain may be removed, called ‘hemispherectomy’, or disconnected, called ‘hemispherotomy’. Here, epilepsy brain surgery can offer a cure for the epilepsy. A child with Rasmussen syndrome having this surgery will be left with a permanent weakness (hemiplegia). However, without surgery, the condition will continue to worsen with progressive weakness down the affected side leading to complete loss of function, impossible to treat seizures and loss of cognitive (learning) skills. So, although surgery is not an easy decision, it may be the best treatment available.  

Information about treatments for children can be found on the Medicines for Children website.

Your child is very likely to have prolonged or repeated seizures as part of Rasmussen syndrome. Your child’s hospital doctor (paediatrician or paediatric neurologist) will discuss a ‘rescue’ or emergency care plan with you to treat any prolonged or repeated seizures.

There may be research studies open that are relevant to this epilepsy syndrome. Your child’s hospital doctor will be able to discuss this with you.


After a period, usually of some years, the inflammatory process seems to stop of its own accord and doesn’t get any worse. Unfortunately, however, the nerve cells that have been injured continue to malfunction. As a result, the epilepsy may continue, although there is usually a better chance at this stage of bringing it under control. The inflammation may be fairly widespread within the substance of the brain. Most children with this condition also have a hemiparesis (weakness) and have some learning difficulties. This makes an assessment of the child’s educational strengths and weaknesses very important. Assessments will include physiotherapy, occupational therapy and psychology. The results of these assessments will help provide the necessary help and encouragement in school.


Helpline: 0808 808 3555
Website: cafamily.org.uk
Email: info@cafamily.org.uk 

HemiHelp is a charity providing support and information to people with hemiplegia and their families in the UK.
Website: hemihelp.org.uk

What is a syndrome?

A syndrome is a group of signs and symptoms that, added together, suggest a particular medical condition. In epilepsy, examples of these signs and symptoms would be things like the age at which seizures begin the type of seizures, whether the child is male or female and whether they have physical or learning disabilities, or both. The results of an electroencephalogram (EEG) are also used to help identify epilepsy syndromes.

If you would like to know more about an epilepsy syndrome, please speak to your doctor. If you would like to know more about epilepsy in general, please contact Epilepsy Action.


Epilepsy Action would like to thank Dr Richard Appleton, consultant paediatric neurologist at Alder Hey Children’s Hospital, Liverpool, UK for preparing this information.

This information is exempt under the terms of Epilepsy Action's information quality standards.

  • Updated November 2016
    To be reviewed November 2019

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