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Rasmussen Encephalitis

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NORD is very grateful to W. Mathern, MD, Professor and Neurosurgical Director, Pediatric Epilepsy Surgery Program, Departments of Neurosurgery and Psychiatry & Biobehavioral Medicine, Mattel Children's Hospital, David Geffen School of Medicine, UCLA; William Davis Gaillard, MD, Professor, Pediatrics and Neurology, George Washington University School of Medicine, Professor Neurology, Georgetown University, Chief, Epilepsy, Neurophysiology, and Critical Care Neurology, Children's National Medical Center, Associate Director, Center for Neuroscience Research, Children's Research Institute; J Helen Cross, The Prince of Wales's Chair of Childhood Epilepsy UCL-Institute of Child Health, Great Ormond Street Hospital for Children & Young Epilepsy and Head of Neurosciences Unit, UCL-Institute of Child Health, London, for assistance in the preparation of this report.

Synonyms of Rasmussen Encephalitis

Disorder Subdivisions

General Discussion

Rasmussen encephalitis, sometimes referred to as Rasmussen syndrome, is a rare disorder of the central nervous system characterized by chronic inflammation (encephalitis) of one hemisphere of the brain. As a result, the patient experiences frequent episodes of uncontrolled electrical disturbances in the brain that cause epileptic seizures (epilepsy). Further symptoms may include progressive weakness of one side of the body (hemiparesis), language problems (if on the left side of the brain) and intellectual disabilities. The exact cause of this disorder is not known. The two leading ideas are that the brain inflammation might be a reaction of a foreign antigen (infection) or an autoimmune disease limited to one side of the brain resulting in brain damage.

It occurs mostly, but not always, in children between the ages of two and ten years, and in many cases the course of the disease is most severe during the first 8 to 12 months. After the peak inflammatory response is reached, the progression of this disorder appears to slow or stop and the patient is left with permanent neurological deficits.


Typically, affected individuals develop focal seizures that may progress to near continuous seizures termed epilepsia partialis continua (EPC). EPC is characterized by a rapid, rhythmic succession of contractions and relaxations of a muscle or muscle group (myoclonus), particularly of the arms, legs, and face, that may occur singularly or in a repetitive, continuous series. In Rasmussen this occurs consistently on one side of the body.

In most cases, affected children will exhibit progressive paralysis of one side of the body (hemiparesis) and if the seizures continue developmental disabilities. In many cases, the development of physical and mental abilities of affected children may cease (developmental arrest). In addition, affected children may lose previously acquired physical and mental abilities (developmental regression). In some cases, affected children may exhibit degeneration (atrophy) of one side of the brain and/or progressive confusion, disorientation, and deterioration of intellectual abilities (dementia).


The exact cause of Rasmussen encephalitis is not known. Most researchers now suspect that Rasmussen encephalitis is an autoimmune disorder following review of the tissue involved under the microscope. In autoimmune disorders, the body's natural defenses (antibodies) fight its own tissue, mistaking it for foreign organisms for no apparent reason.

Some researchers believe that Rasmussen encephalitis may be triggered by an unidentified infection such as influenza, measles, or cytomegalovirus.

Affected Populations

Rasmussen encephalitis mostly affects children ten years of age and younger. It is unusual to affect children under two years of age. Adolescents and young adults in much smaller proportions are also affected. There may be a history of some prior mild cold or flu prior to the onset of the seizures. The annual number of new-onset Rasmussen has been estimated as 2.4/107 persons less than or equal to 18 years of age.

Related Disorders

Symptoms of the following disorders may be similar to those of Rasmussen encephalitis. Comparisons may be useful for a differential diagnosis:

Focal cortical dysplasia in the motor region refers to lesions near the motor-sensory cortex that can provoke EPC which is similar to RE.

Alpers-Huttenlocher syndrome is caused by mutations in the POLG1 gene and characterized by childhood-onset progressive and ultimately severe encephalopathy with intractable epilepsy and liver failure.

Standard Therapies

Rasmussen encephalitis may be diagnosed based upon a thorough clinical evaluation, a detailed patient history, and a complete neurological evaluation including advanced techniques such as electroencephalography (EEG), and magnetic resonance imaging (MRI).

During an EEG, the brain's electrical impulses are recorded. Such studies may reveal brain wave patterns that are characteristic of certain types of epilepsy. During MRI, a magnetic field and radio waves are used to create cross-sectional detailed images of the brain. It is usual that the diagnosis is made after a minimum of two scans which will detail progressive shrinkage of the affected side of the brain

Treatment of Rasmussen encephalitis is mostly symptomatic and supportive. Special services that may be beneficial to affected children include special social support, physical therapy, and other medical, social, and/or vocational services.

Various anti-seizure medications (anticonvulsants) may be prescribed to treat seizures. However, in most cases, anticonvulsants have proven ineffective. Medical treatments targeted at possible autoimmune disease may be tried, including steroids, immunoglobulin and tacrolimus. Immunological therapies (tacrolimus, intravenous immunoglobulins, potentially others as well) may slow down the neurological and structural deterioration but usually does not improve the epilepsy. Its precise role in management of Rasmussen encephalitis remains to be determined

Surgery usually in the form of a cerebral hemispherectomy is the only way to cure the seizures and halt neurodevelopmental regression. However, there is the inevitable resultant functional deficits including hemiparesis (weakness of one side) and hemifield defect (impairment of vision to one side), and where the dominant side of the brain is affected, there may be an effect on language. The difficulty is often deciding on the necessary and best timing of surgery, dependent on the severity of epilepsy and degree of effect on learning. The decision needs to be made jointly by the family and specialist center who deal with this condition regularly.

Investigational Therapies

The RE Children's Project (http://www.rechildrens.org) a non-profit non-government organization has established a research consortium among US and international research laboratories to identify the cause of Rasmussen encephalitis and develop new more effective treatments. In order to develop new therapies, this group is soliciting families and patients to volunteer their brain tissue obtained at surgery for research. Contact RE Children's Project for more information.

Information on current clinical trials is posted on the Internet at www.clinicaltrials.gov. All studies receiving U.S. government funding, and some supported by private industry, are posted on this government web site.

For information about clinical trials being conducted at the NIH Clinical Center in Bethesda, MD, contact the NIH Patient Recruitment Office:

Toll-free: (800) 411-1222
TTY: (866) 411-1010
Email: prpl@cc.nih.gov

For information about clinical trials sponsored by private sources, contact:

Contacts for additional information about Rasmussen encephalitis:

Gary W. Mathern, MD
Professor and Neurosurgical Director, Pediatric Epilepsy Surgery Program
Departments of Neurosurgery and Psychiatry & Biobehavioral Medicine
Mattel Children's Hospital
David Geffen School of Medicine
University of California, Los Angeles
Telephone: 310-825-7961
Fax: 310-825-0922
Email: gmathern@ucla.edu

William Davis Gaillard, MD
Professor, Pediatrics and Neurology
George Washington University School of Medicine
Professor Neurology
Georgetown University
Chief, Epilepsy, Neurophysiology, and Critical Care Neurology
Children's National Medical Center
Associate Director, Center for Neuroscience Research
Children's Research Institute
Telephone: 202-476-2120
Email: wgaillar@childrensnational.org

J. Helen Cross
The Prince of Wales's Chair of Childhood Epilepsy UCL-Institute of Child Health, Great Ormond Street Hospital for Children & Young Epilepsy

Head of Neurosciences Unit
UCL-Institute of Child Health
4/5 Long Yard
London WC1N 3LU
Telephone number: 0207 599 4105
Fax Number: 0207 430 0032
Mobile: 07983420692
PA Anne Brown: anne.brown@ucl.ac.uk

The Neville Epilepsy Centre
Young Epilepsy
St Piers Lane,
Surrey RH7 6PW
PA: Louise Jones ljones@youngepilepsy.org.uk
Tel: 01342 831212

Rasmussen Encephalitis Resources



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Tubbs RS, Nimjee SM, Oakes WJ. Long-term follow-up in children with functional hemispherectomy for Rasmussen's encephalitis. Childs Nerv Syst. 2005;21:461-65.

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NINDS Rasmussen's Encephalitis Information Page. National Institute of Neurological Disorders and Strokes. National Institutes of Health. www.ninds.nih.gov/disorders/rasmussen/rasmussen.htm. Last Updated December 19, 2011. Accessed November 14, 2012.

Rasmussen's encephalitis. Wikipedia. http://en.wikipedia.org/wiki/Rasmussen's_encephalitis. Last modified November 9, 2012. Accessed November 14, 2012.

Rasmussen's Encephalitis. The Hemispherectomy Foundation. http://hemifoundation.intuitwebsites.com/rasmussen.html. Accessed November 26, 2012.

Report last updated: 2012/11/27 00:00:00 GMT+0