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Rasmussen’s Encephalitis: Symptoms, Causes, Treatment, Diagnosis

What is Rasmussen’s Encephalitis?

Rasmussen’s Encephalitis is a neurological condition in which only one hemisphere or half of the brain is affected. Encephalitis is a condition in which brain inflammation occurs and Rasmussen’s encephalitis is characterized by the deterioration and inflammation of the one cerebral hemisphere resulting in seizures, loss of motor skills, paralysis on one side of the body and sometimes even dementia. The deterioration that occurs in the brain due to Rasmussen’s encephalitis is irreversible even though the condition may get cured.

The condition is named after Theodore Brown Rasmussen, who was an American neurosurgeon and worked as the Head of the Montreal Neurological Institute.

Rasmussen's Encephalitis

Other Names for Rasmussen’s Encephalitis

Other names for Rasmussen’s encephalitis include Chronic Focal Encephalitis (CFE), Rasmussen’s Syndrome and Chronic Localized Encephalitis etc. It can also be referred to as chronic encephalitis.

Most Susceptible People to Rasmussen’s Encephalitis

Children form the most susceptible age group to Rasmussen’s encephalitis. Most frequently observed cases of Rasmussen’s encephalitis are in children who are less than 15 years in age, most often from 1 year old to 14 years old are targeted. The average age for Rasmussen’s encephalitis is 6 years. Although it is true that it mostly occurs in children but one out of ten people suffering from Rasmussen’s encephalitis is an adult.

Causes of Rasmussen’s Encephalitis

Some researchers believe that the cause for Rasmussen’s encephalitis is a virus that causes infection in the brain that leads to the deterioration of the brain while others argue that it is an auto-immune disorder that is caused by the formation of antibodies by the body. Despite all this conjecture, the cause for Rasmussen’s encephalitis is still unknown.

Whether it is because of a virus or antibodies, the chronic inflammation of the brain that occurs in Rasmussen’s encephalitis is due to the infiltration of T-lymphocytes in its tissues leading to the dystrophy of the brain which is the cause for various symptoms especially epilepsy.

Epilepsy, a symptom of Rasmussen’s encephalitis, also causes further damage to the brain. It is believed that epilepsy occurs due to a disturbance in GABA release. GABA is a neurotransmitter of the brain of mammals and is actually the most important inhibitory neurotransmitter that occurs in them.

Symptoms of Rasmussen’s Encephalitis

Rasmussen’s Encephalitis actually occurs in two stages and is sometimes preceded by a prodromal stage. The two stages are given below:

Symptoms of Rasmussen’s Encephalitis in Prodromal Stage

This early stage of Rasmussen’s encephalitis is marked with an intermediate frequency of focal onset seizures. The stage is usually of few months duration. No hemiparesis occurs in this stage of Rasmussen’s encephalitis.

Symptoms of Rasmussen’s Encephalitis in Acute Stage

Acute stage of Rasmussen’s encephalitis is marked by the active inflammation and progressively worsening symptoms which are as follows:

  • Hemiparesis which is progressively increasing weakness in one side of the body.
  • Hemianopia or Hemianopsia which refers to a condition in which the person loses vision of one side of the visual field.
  • Intellectual and cognitive difficulties such as of learning and memory etc.
  • Language problems if the affected part is left side of the brain.
  • Epileptic Seizures also constitute a major part of the symptoms.
  • Epilepsia Partialis Continua which are a kind of motor epileptic seizures affecting hands and face and are very difficult to control with the use of drugs.

These were some of the most common symptoms of Rasmussen’s encephalitis. Acute stage of Rasmussen’s encephalitis is usually of four to eight months duration.

Symptoms of Rasmussen’s Encephalitis in Chronic Stage

Also known as the Residual Stage, this stage of Rasmussen’s encephalitis is marked with almost all the same symptoms that occur in the acute stage of Rasmussen’s encephalitis. The inflammation becomes inactive even though the symptoms suggest otherwise. This is because the brain degradation that happens in Rasmussen’s encephalitis is irreversible. The severity of these symptoms differs from person to person.

Diagnosis of Rasmussen’s Encephalitis

The following procedures may be followed by the doctors to determine the occurrence of Rasmussen’s encephalitis:

  • Since the symptoms for Rasmussen’s encephalitis are pretty distinct, a diagnosis may be made on them alone after doing some tests to rule out other possibilities.
  • An EEG can also be done to show the slowing of brain activity due to the dystrophy that occurs in brain due to Rasmussen’s encephalitis.
  • MRI can also be ordered by doctors to show the inflammation that occurs in the brain due to Rasmussen’s encephalitis. It can also be used to show brain dystrophy and shrinkage that occurs in the brain of a person when he is suffering from Rasmussen’s encephalitis.
  • Even though not always prescribed or necessary, brain biopsy can provide pretty concrete evidence as to the presence of Rasmussen’s encephalitis in a person.

Treatment of Rasmussen’s Encephalitis

Treat of Rasmussen’s encephalitis is done according to the stage of the disease. Some of the treatment procedures are given here:

Treatment of Rasmussen’s Encephalitis in Acute Stage

In acute stage of Rasmussen’s encephalitis, those treatments are prescribed which can control the inflammation of the brain. The drugs that can suppress immune response of the body are used to treat Rasmussen’s encephalitis as well. Even though they cannot prevent permanent injury of the brain leading to various disabilities, some of the treatments that are used to fight inflammation in Rasmussen’s encephalitis are as follows:


Just like in any other inflammatory disease, steroids are used first to curb the symptoms of Rasmussen’s encephalitis. This can be used in two ways. In the first one, high dosage of the corticosteroids are used for short periods while in the second one, low dosages are used for longer durations.

Intravenous Immunoglobulin

This is actually the first medicine that is prescribed in the Rasmussen’s encephalitis, if an adult is suffering from it. This can also be done for short periods as well as longer periods.

Other Treatments

These include Plasmapheresis and Tacrolimus. Plasmapheresis is a technique in which blood is removed from the body and is returned to the body again after treatment. On the other hand, tacrolimus is an immune-suppressive drug. These two are used to cure Rasmussen’s encephalitis.

Treatment of Rasmussen’s Encephalitis in Residual Stage

This is the stage Rasmussen’s encephalitis where the infection is no longer active. So the focus of the treatment is to cure the residual symptoms, out of which epilepsy is the most problematic. Since the use of epileptic drugs is ineffective in the treatment of epileptic symptoms caused by Rasmussen’s encephalitis, surgery is the most effective treatment.


It is a surgical procedure to remove or disconnect the affected cerebral hemisphere from the rest of the brain. Even though it can result in a further increase in problems such as cognitive difficulties, increased weakness and a loss of vision, it is still the most effective way to get rid of epilepsy caused by Rasmussen’s encephalitis.

People suffering from Rasmussen’s encephalitis in the left cerebral hemisphere are advised not to go through the process as it can lead to the loss of speech and language etc. This is due to the fact that the left part of the brain controls language.

Philanthropic Efforts for Rasmussen’s Encephalitis

There are many things that are still unknown about Rasmussen’s encephalitis, hence the necessity for ongoing research. One such organization is The RE Children’s Project that was founded in 2010. It was founded to support the ongoing research about Rasmussen’s encephalitis and to increase awareness about the disease as well.

Encephalitis society of United Kingdom and The Hemispherectomy Foundation of America are other such organizations that are working towards finding a cure for Rasmussen’s encephalitis and eradicating the disease.

Rasmussen’s encephalitis is a disease that needs further research for its successful cure and if we can donate something to the cause, even if it is only information, then it is a step in the right direction.


  1. National Organization for Rare Disorders (NORD). (2022). Rasmussen Encephalitis. https://rarediseases.org/rare-diseases/rasmussen-encephalitis/
  2. Epilepsy Foundation. (2022). Rasmussen’s Encephalitis. https://www.epilepsy.com/learn/types-epilepsy-syndromes/rasmussens-encephalitis

Also Read:

Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:August 31, 2023

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