Rasmussen Syndrome

22nd April 2020

Rasmussen syndrome is very rare and it is thought to only occur in 1 in 750,000, although an exact figure is not yet currently known. This particular syndrome usually affects children between the ages of 6 and 8, however, there have been instances where a diagnosis has been made in children as young as 2 years and even more rarely during adulthood. 

With Rasmussen syndrome, the brain cells in one hemisphere of the brain become inflamed and swollen. At present, the reason for the inflammation and swelling is not known and it’s very rare that both hemispheres are affected. There is no evidence of viral infection in the majority of cases.    


As a result of the inflammation, nerve cells start to malfunction and this results in seizures. Seizures often start infrequently and increase until they become extremely frequent and occur multiple times a day. The seizures associated with Rasmussen syndrome are most often focal (patial), which usually causes one side of the face or body to jerk rhythmically. Unfortunately, these seizures are often very difficult to control with anti-epileptic medications (AEDs). 

As a result of frequent and prolonged seizures, the person will often develop a weakness in the affected side of the body. This is also known as ‘hemiparesis’ and can worsen to the point that the limbs lose function.  

Many people with Rasmussen syndrome will experience learning and development issues as a result of the seizures or as a side effect of the medications. The hemisphere that’s affected by Rasmussen syndrome can cause other difficulties, such as language, loss of vision in one or both eyes (hemianopia) or difficulty swallowing. 


An electroencephalogram (EEG) is often used to diagnose Rasmussen syndrome. The EEG will show a pattern that’s known as Periodic Lateralising Epileptiform Discharges (PLEDs), which is continuous abnormal activity in the affected hemisphere of the brain. 

Magnetic Resonance Imaging (MRI) tests may appear normal or only slightly abnormal at first, but will become more markedly abnormal within a few months of the condition. This will continue to deteriorate as the syndrome progresses. 


Treatment of Rasmussen syndrome is notoriously difficult and at present there is no treatment that is thought to be more effective than any other. The most common AEDs prescribed for those with the syndrome are carbamazepine, levetiracetam, topiramate and clobazam.

Medicines that alter or stop the immune system may be prescribed such as steroids, immunoglobulins, azathioprine and tacrolimus. In some cases, these may help to control seizures and slow the progression of Rasmussen syndrome. 

Surgery may be recommended to treat Rasmussen syndrome and prevent further brain injury from occurring. In some cases, the syndrome is confined to a part of the brain that can be safely removed, commonly the temporal lobe. A hemispherectomy may also be recommended, which is where the affected hemisphere is disconnected from the healthy one. Although surgery can offer a ‘cure’ for epilepsy, there are often side effects, such as weakness, speech loss or difficulty swallowing. Find out more about epilepsy surgery in our earlier post here. 


In most cases, the inflammation will stop of its own accord after a number of years. Unfortunately, the epilepsy may continue as the damaged nerve cells will often continue to malfunction. However, at this time there is increased potential for bringing the seizures under control. 

Children who have Rasmussen syndrome will often continue to have learning and development issues into adulthood, as well as weakness (hemiplegia). These people will often require ongoing physiotherapy, occupational therapy, speech and language therapy and psychology.

National Epilepsy Training can help…

For more information on Rasmussen syndrome, please call us on 01706 373075 or email admin@nationalepilepsytraining.co.uk