Rasmussen’s Encephalitis

Rasmussen’s encephalitis (RE) is a very rare, chronic inflammatory neurological disease that usually affects only one hemisphere (half) of the brain. It most often occurs in children under the age of 10 but can also affect adolescents and adults.

RE has features of an autoimmune disease in which immune system cells enter the brain and cause damage. The disease is characterized by:

• Frequent and severe seizures
• Inflammation of the brain (encephalitis)
• Mental deterioration
• Progressive loss of neurological functions including motor skills, speech and eventual paralysis on one side of the body (hemiparesis)

Children with RE frequently enter a phase of permanent, but stable, neurological deficits after eight to 12 months; the disease in adults and adolescents may continue to progress slowly.

There are three stages of Rasmussen’s encephalitis:

• Prodromal stage: Non-specific, low seizure frequency and mild hemiplegia
• Acute stage: Frequent seizures, often epilepsia partialis continua; progressive hemiparesis, hemianopia, cognitive deterioration and aphasia (if dominant hemisphere affected)
• Residual stage: Permanent and stable neurological deficits and continuing seizures

The cause of Rasmussen’s encephalitis is unknown. On the basis of the earliest detection, the inflammation in the brain seems to be driven by an antigen, which could be foreign (an infectious agent) or autoimmune. Another possibility could be that Rasmussen’s encephalitis is the result of the immune system’s poor response to an otherwise minor antigen. This issue could be genetic.

Although much progress has been made in establishing the cause, the triggers and markers of those at risk for Rasmussen’s encephalitis remain unknown. This neurological disease is rare, affecting only about two in every 10 million people, typically targeting children between the ages of two and 10.  Causes of encephalitis infections include bacteria, viruses, fungi and parasites. For some individuals, environmental exposure (such as a parasite), recent travel or an immunocompromised state (such as HIV, diabetes, steroids, chemotherapy treatment) are important risk factors.

Individuals who present with symptoms of Rasmussen’s encephalitis (RE) will be evaluated with a magnetic resonance imaging (MRI) scan, a computed tomography (CT) scan and/or an electroencephalogram (EEG) test. These screenings will reveal a detailed map of brain activity and determine whether RE is present.

Rasmussen’s encephalitis (RE) has features of an autoimmune disease in which immune system cells enter the brain and cause damage. The disease is characterized by:

• Frequent and severe seizures
• Inflammation of the brain (encephalitis)
• Mental deterioration including loss of motor skills, loss of speech, and confusion
• Paralysis on one side of the body

Children with RE frequently enter a phase of permanent, but stable, neurological deficits after eight to 12 months; the disease in adults and adolescents may continue to progress slowly.

Rasmussen’s encephalitis (RE) is typically clinically diagnosed through a medical evaluation, a complete neurological evaluation, an electroencephalography (EEG), magnetic resonance imaging (MRI) and a thorough patient history.

Anti-epileptic drugs may be prescribed but may not entirely control seizures. Recent studies have shown some success with treatments that suppress or modulate the immune system, in particular those that use corticosteroids, intravenous immunoglobulin or tacrolimus. Surgery to control seizures may be recommended, particularly in children where recovery potential is high.

The outlook for individuals with Rasmussen’s encephalitis (RE) varies. For some children, surgery may halt disease progression and stabilize seizures. However, most individuals with RE are left with some paralysis, cognitive deficits and problems with speech. In some very rare cases, the disease can progress to involve the opposite brain hemisphere.

RE is considered a rare disease, which often means there is not much information known about it. This is usually the case because doctors and researchers do not see many people with RE, which makes it hard to learn from them through observations or large studies.

Consider participating in a clinical trial so clinicians and scientists can learn more about RE and related disorders. Clinical research uses human volunteers to help researchers learn more about a disorder and perhaps find better ways to safely detect, treat or prevent disease.

All types of volunteers are needed—those who are healthy or may have an illness or disease—of all different ages, sexes, races, and ethnicities to ensure that study results apply to as many people as possible, and that treatments will be safe and effective for everyone who will use them.

For information about participating in clinical research, visit NIH Clinical Research Trials and You. Learn about clinical trials currently looking for people with RE at Clinicaltrials.gov.