Rasmussen syndrome

Fernando Cendes MD PhD (Dr. Cendes of the University of Campinas - UNICAMP has no relevant financial relationships to disclose.)
Jerome Engel Jr MD PhD, editor. (Dr. Engel of the David Geffen School of Medicine at the University of California, Los Angeles, has no relevant financial relationships to disclose.)
Originally released April 12, 1999; last updated June 8, 2020; expires June 8, 2023

This article includes discussion of Rasmussen syndrome, Rasmussen encephalitis, and chronic focal encephalitis. The previous terms may include synonyms, similar disorders, variations in usage, and abbreviations.


Rasmussen syndrome is a rare disease defined by intractable epilepsy, progressive hemiparesis, and deterioration of mental capacity with usual onset in childhood. The epilepsy most often manifests itself as epilepsia partialis continua. Focal motor seizures are most commonly refractory to antiepileptic medications. Because the disorder is still a rare entity, a definite etiology has not been delineated, but it is thought to be an autoimmune disorder. Numerous immunosuppressive therapies have been attempted due to the presumed inflammatory etiology based on histopathology. The only curative measure has been hemispherectomy after the development of a fixed hemiparesis. In this article, the author discusses advances in the treatment of Rasmussen syndrome.

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 antiepileptic drugs, steroids, plasma exchange, and immunoglobulins, are attempted to treat Rasmussen syndrome.


• Hemispherectomy is the only effective treatment to reduce seizure frequency and prevent 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 (Rasmussen et al 1958). Their report describes 3 children with intractable focal seizures and progressive hemiparesis refractory to antiepileptic treatment. Hemispherectomy in 2 cases resulted in the improvement of hemiparesis and resolution of seizure activity. Pathology of brain tissue in all 3 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.

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 describes 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 (Kozhevnikov 1991). 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 (Panayiotopoulos 2010). The revision of seizure terminology by the ILAE commission on classification and terminology lists Rasmussen syndrome under the category “distinctive constellations” (Berg et al 2010).

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