Rasmussen syndrome is a type of chronic encephalitis (brain inflammation). It usually affects a single hemisphere (half) of the brain. It is progressive, meaning that it gets worse over time.
Rasmussen syndrome causes progressive focal onset seizures, mental deterioration and loss of movement skills and speech. It is a rare condition with severe and disabling effects.
What are other terms for Rasmussen syndrome?
Other terms for Rasmussen syndrome include:
- chronic focal encephalitis of Rasmussen
- chronic progressive epilepsia partialis continua of childhood
- Rasmussen encephalitis
What are the features of Rasmussen syndrome?
Rasmussen syndrome usually begins when the child is between six and 10 years old, but the age of onset can vary between 12 months and 15 years of age. Some rare cases have been seen in older teenagers and young adults.
The child’s first seizure is usually a focal motor, focal sensory or tonic-clonic seizure. The seizures are frequent and may be prolonged. They often do not respond to anti-seizure medications. In about 20 per cent of children with this syndrome, the first seizure turns into status epilepticus.
In most cases, the child will have something called epilepsia partialis continua. This is a form of focal status epilepticus. The child has repeated or ongoing motor seizures, such as twitching of face/mouth and hand jerking. The seizures happen in the same region and look the same each time. The child usually remains conscious and aware.
The child slowly loses motor skills on the same side of the body as the focal seizures. They start to develop hemiparesis (weakness or partial paralysis on the affected side of the body), usually within a year after the start of seizures, although it can be up to 10 years later in older children and adults. They may also develop problems with their vision on the affected side. Up to 85 per cent of children start to lose mental abilities, intelligence and speech. Speech problems are more common if the left hemisphere is involved. On imaging studies, the affected side of the brain atrophies (shrinks). The child’s EEG becomes very abnormal.
After two to 10 years, the child’s neurological deterioration stops. The child then has fewer seizures but permanent motor and cognitive deficits.
What causes Rasmussen syndrome?
It is not clear what causes the brain inflammation. An autoimmune reaction, in which the body’s immune system attacks nerve cells and causes the inflammation to spread, is suspected. It may begin after the brain is infected with a virus, such as cytomegalovirus (CMV) or herpes virus. However, there is no evidence for viral infection in many cases, and it is possible that there are several possible triggers.
The disease does not have a seasonal pattern and does not seem to cluster in places or run in families. It is not infectious nor contagious. You cannot catch it from another person.
How many other children have Rasmussen syndrome?
Rasmussen syndrome is very rare. It affects approximately two in every 10 million people.
How do you know that a child has Rasmussen syndrome?
Rasmussen syndrome is difficult to diagnose in the early stages. Once the child develops epilepsia partialis continua, hemiparesis and cognitive impairment, the diagnosis is easier to make. MRI studies of the brain showing atrophy of one hemisphere can be suggestive of the diagnosis. However, sometimes these changes are not present at the onset of the seizures. Imaging studies also help to rule out other possible causes for these symptoms, such as a tumour or other structural problem with the brain. Brain biopsy may be required to make the diagnosis.
How is Rasmussen's encephalitis diagnosed?
Rasmussen’s encephalitis is diagnosed through a medical history, examination showing hemiparesis, MRI of the brain showing atrophy (shrinkage) of one hemisphere and EEG abnormalities on that side. A video-EEG is usually performed to confirm the seizure onset and other EEG abnormalities. Sometimes, a brain biopsy may be done if the diagnosis is not clear on MRI and EEG.
How is Rasmussen syndrome treated?
Anti-seizure medications usually do not lead to seizure freedom but may help to decrease the seizure burden.
Immunotherapy (steroids, plasmapheresis, intravenous immunoglobulin) at the early stages may help manage seizures or prevent further immune-related brain damage.
Epilepsy surgery is the most effective treatment. This needs to be individually tailored to each child. At the moment, the most effective treatment is surgery to remove or disconnect all or part of the affected hemisphere of the brain (hemispherectomy). There are no controlled studies of this procedure, but in most cases, it helps to reduce the number of seizures and even stop them. The surgical treatment can also prevent or even reverse further cognitive deterioration. It is usually not considered until later stages of the disease, when the child has lost quite a lot of movement on the affected side of their body.
Hemispherectomy is a major surgical procedure that will always result in weakness on one side of the body (opposite to the affected brain hemisphere). Most children who have this surgery have already lost the function of the affected hemisphere, so they already have hemiparesis and other speech/cognitive deficits. Because the child’s brain is still developing, the remaining “healthier” hemisphere may be able to take on many of the tasks that are normally performed by the affected hemisphere. Before and after this surgery is done, the child will need detailed assessments by occupational and physical therapists and neuropsychological assessments to determine the effects of the disease on the body.
What is the outlook for a child with Rasmussen syndrome?
Rasmussen syndrome is a progressive disorder that results in weakness or paralysis of one side of the body and cognitive impairment. Treatment may help to halt the progression of the disease.
In some children, surgery is indicated to reduce the number of seizures. After the surgical treatment, seizures are expected to become controlled. However, motor and cognitive problems will require continuous rehabilitation.
