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  • Updated 02.26.2024
  • Released 04.12.1999
  • Expires For CME 02.26.2027

Rasmussen syndrome



Rasmussen syndrome is a rare disease defined by pharmacoresistant epilepsy, progressive hemiparesis, and deterioration of mental capacity with usual onset in childhood. The epilepsy often manifests as epilepsia partialis continua. Focal motor seizures are most commonly refractory to antiseizure medications. Because the disorder is still a rare entity, a definite etiology has not been delineated, but mounting evidence indicates that it is an autoimmune disorder. Numerous immunosuppressive therapies have been attempted due to the presumed inflammatory etiology based on histopathology immunological studies. The only curative measure has been hemispherectomy after the development of a fixed hemiparesis.

Key points

• Rasmussen syndrome is a progressive disorder, predominately with childhood onset and characterized by intractable epilepsy, hemiparesis, and neurologic decline.

• Rasmussen syndrome is a rare immune-mediated reaction for which an etiology has yet to be determined.

• Various treatments, such as antiseizure medications, steroids, plasma exchange, immunoglobulins, and other immunomodulatory drugs, have been attempted to slow clinical progression of Rasmussen syndrome.

• Hemispherectomy is the only effective treatment to control seizures and prevent cognitive deterioration.

• Controversy exists as to whether hemispherectomy should be performed early in the disease course due to the anticipated disability or after deficits become fixed.

Historical note and terminology

The first cases of what is now called Rasmussen encephalitis or Rasmussen syndrome was referred to as chronic focal encephalitis in 1958 by Dr. Theodore Rasmussen and his colleagues at the Montreal Neurological Institute (49). Their report describes three children with focal seizures and progressive hemiparesis refractory to antiseizure medications. Hemispherectomy in two cases resulted in the improvement of hemiparesis and resolution of seizure activity. Pathology of brain tissue in all three cases demonstrated inflammatory changes, leading to the theory that the disease process was secondary to focal encephalitis. An etiology was not determined, but the disease was thought to be virally mediated. Many years later, the etiology remains elusive, but studies indicate an autoimmune disease with T cell-mediated neuronal death (54; 45; 34; 60; 67).

However, there are reports of cases described by Kozhevnikov, a Russian neurologist in the 1880s, suggesting that this disease process has existed for centuries. He described patients with unilateral focal motor seizures, using the term epilepsia corticalis sive partialis continua to depict a continuous epilepsy syndrome. His account describes men of varying age suffering from persistent focal motor seizures that progressed to generalized convulsions in some. These men then developed unilateral weakness that was observed to be progressive on the side affected by seizure activity. He did not find an etiology to explain the syndrome but did suggest a chronic inflammatory process (36). It is fascinating that Kozhevnikov thought of operating on these patients, as he could find no cure. Unfortunately, he was refused the opportunity to perform autopsies on this group of patients. This syndrome has become known as Kozhevnikov epilepsy, thought to be common in Siberia.

In the 1989 International League Against Epilepsy (ILAE) classification, Rasmussen syndrome was introduced as a synonym of Kozhevnikov type 2 syndrome; eventually, the name Kozhevnikov was removed (47). The revision of seizure terminology by the ILAE commission on classification and terminology lists Rasmussen syndrome under the category “distinctive constellations” (07).

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