By: Iris Zhao
What is Rasmussen Syndrome?
Rasmussen syndrome, also referred to as Rasmussen encephalitis, is a very rare neurological condition that gets worse over time. Rasmussen syndrome is found in two out of every ten million people and most commonly affects children between two and ten years old (Cleveland Clinic, 2023). It can also occur in adolescents and adults; however, it is less common. People with Rasmussen syndrome generally experience frequent episodes of epileptic seizures resulting from inflammation in one region or hemisphere of the brain (Patil, 2022).
Causes
The cause of Rasmussen syndrome continues to be under investigation. However, researchers have proposed two potential causes for this inflammation of the brain.
Researchers have proposed it may be caused by an autoimmune disease where the body’s natural defenses (antibodies and T-cells) mistakenly attack its own tissues without a clear cause (National Organization for Rare Disorders, 2023). They have also proposed that it could be an infection resulting from an unidentified virus in the brain, such as influenza, measles, or cytomegalovirus (Cleveland Clinic, n.d.; National Organization for Rare Disorders, 2023).
Signs and Symptoms
The first sign of Rasmussen’s syndrome typically occurs as a seizure that occurs in several types:
Generalized tonic-clonic seizures: A seizure that causes strong muscle movements on the sides of the body, including convulsions.
Simple partial seizures (focal awareness): A seizure that occurs while someone is awake and aware of their surroundings, and may lead to the twitching of one hand or arm.
Complex partial seizures (focal impaired awareness): A seizure that begins in one side of your brain and changes your level of awareness.
Longer seizures (epilepsia partialis continua): This seizure manifests as a condition called epilepsia partialis continua (EPC), which is when seizures happen every few seconds or minutes.
(Cleveland Clinic, 2023; Patil, 2022)
After the initial seizure, most affected children may exhibit symptoms including:
- Cognitive loss or mental decline, such as issues with thinking, intellect, and memory
- Weakness in the arms and legs on one side of the body
- Progressive paralysis of one side of the body (hemiparesis)
- Progressive loss of speech and language abilities (aphasia)
- Partial loss of sight in half of your visual field (hemianopsia)
(Cleveland Clinic, 2023; National Organization for Rare Disorders, 2023; Patil, 2022)
Symptoms are usually restricted to one side of the body because only half of the brain is typically affected. If motor and vision problems are present, they will occur on the side opposite to the affected side of the brain (Patil, 2022). Rasmussen syndrome is always most severe during the first 8 to 12 months after the initial seizure, and the progression of the condition tends to slow down afterward, but the neurological damage remains permanent (Cleveland Clinic, 2023).
Stages of Rasmussen Syndrome
Over months or years, these seizures can negatively affect parts of the brain’s function. There are three stages associated with Rasmussen syndrome.
In the prodromal stage, neurological issues are absent; however, the person will experience occasional focal seizures that occur infrequently (Patil, 2022). In the acute stage, the affected side of the brain shrinks, causing more frequent seizures. The shrinkage of the brain negatively impacts brain functioning, resulting in neurological symptoms, including muscle weakness, changes in vision, and abnormal speech (Patil, 2022). In the residual stage, there are fewer seizures; however, there is still significant shrinkage in parts of the brain, which continues to lead to severe neurological impairments (Patil, 2022).
Diagnosis
If Rasmussen syndrome is suspected, it is important for the child or adult to see a neurologist for a clinical evaluation of their potential symptoms. Rasmussen syndrome can be diagnosed through a clinical evaluation and a detailed patient history, followed by a neurological evaluation using diagnostic tests and techniques.
Common diagnostic tests that are helpful in diagnosing Rasmussen syndrome include:
Magnetic resonance imaging (MRI): An MRI uses magnetic fields and radio waves to create cross-sectional detailed images of the brain (National Organization for Rare Disorders, 2023). A brain MRI is used at the beginning of the disease to look for atrophy (loss of tissue) of one side of the brain (Cleveland Clinic, 2023.). The diagnosis is usually made after a minimum of two MRI scans that show progressive brain shrinkage on the affected side of the brain (National Organization for Rare Disorders, 2023).
Electroencephalogram (EEG): An EEG records your brain’s electrical activity (Cleveland Clinic, 2023). As seizures are often the first sign of Rasmussen syndrome, an EEG can help reveal how the brain is slowing or causing seizures in a localized area, region, or an entire side (Patil, 2022).
Treatment for Rasmussen Syndrome
At this time, surgery is the only effective cure for seizures due to this condition, but there are a few treatments targeted in controlling seizures and managing symptoms associated with Rasmussen syndrome.
Antiseizure medication may help to decrease the frequency and severity of the seizures (Cleveland Clinic, 2023). Multiple seizure medications may be needed, as standard seizure medications do not work well on their own (Shafer, 2013). Although these medications may help relieve seizures, it is important to note that antiseizure medications have a limited effect and do not completely manage seizures that occur due to Rasmussen syndrome (National Organization for Rare Disorders, 2023; Varadkar, 2014).
If medications are ineffective, brain surgery is considered. Seizures in Rasmussen’s syndrome normally arise from an area on one side of the brain; therefore, surgery in the form of a hemispherectomy is the most effective in curing the seizures by removing large parts of one side of the brain or an entire half of the brain (Cleveland Clinic, 2023; Shafer, 2013). This type of surgery can have consequences, including bleeding, infection, speech deficits, hemiparesis (weakness of one side), hemifield defect (impairment of vision to one side), and motor movement deficits (National Organization for Rare Disorders, 2023; Patil, 2022; Varadkar, 2014).
If early surgical treatment is taken, then it is possible for the brain to compensate for the loss of function, and the risk of further loss of function after surgery is minimal. With proper care and rehabilitation afterward, many children can relearn some activities and have a chance for a better quality of life (Cleveland Clinic, 2023; Patil, 2022; Shafer, 2013).
Shown in a follow-up study on children with Rasmussen’s encephalitis who underwent functional hemispherectomy, researchers found that all of the children experienced the complete elimination of their seizures and were capable of moving on their own (Tubbs et al., 2005). The cohort of patients also remained seizure-free for many years after the study (Tubbs et al., 2005). Nevertheless, it is important to keep in mind the limitations of past studies, including concerns of sample size and potential selection biases.
Conclusion
Rasmussen syndrome, or Rasmussen encephalitis, is a rare, progressive, drug-resistant epileptic condition that is associated with chronic inflammation of one side of the brain. It is most commonly found in children, although less common in adolescents and adults. All treatment options for Rasmussen syndrome should first be discussed with a medical professional. There continues to be ongoing research about the cause of this condition and the expansion of treatment options.
References
Cleveland Clinic. (2023). Rasmussen’s Encephalitis: What It Is, Causes, & Symptoms. Cleveland Clinic. Retrieved from: https://my.clevelandclinic.org/health/diseases/6092-rasmussens-encephalitis#symptoms-and-causes
National Organization for Rare Disorders (NORD). (2023). Rasmussen Encephalitis – Symptoms, Causes, and Treatment. National Organization for Rare Disorders. Retrieved from: https://rarediseases.org/rare-diseases/rasmussen-encephalitis/#disease-overview-main
Patil, R. (2022). Rasmussen Encephalitis. Child Neurology Foundation. Retrieved from: https://www.childneurologyfoundation.org/disorder/rasmussens-encephalitis/
Shafer, P. (2013). Rasmussen’s Syndrome – When It’s More Than Just the Seizures. Epilepsy Foundation. Retrieved from: https://www.epilepsy.com/stories/rasmussens-syndrome-when-its-more-just-seizures
Tubbs, R.S., Nimjee, S.M., & Oakes, W.J. (2005). Long-term follow-up in children with functional hemispherectomy for Rasmussen’s encephalitis. Child’s nervous system: ChNS: official journal of the International Society for Pediatric Neurosurgery, 21(6), 461–465. https://doi.org/10.1007/s00381-005-1136-2
Varadkar, S., Bien, C.G., Kruse, C.A., Jensen, F.E., Bauer, J., Pardo, C.A., Vincent, A., Mathern, G.W., Cross, J.H. (2014). Rasmussen’s encephalitis: clinical features, pathobiology, and treatment advances. The Lancet Neurology, 13(2), 195–205. https://doi.org/10.1016/S1474-4422(13)70260-6
