Information on the following diseases can be found in the Related Disorders section of this report:

• Subacute sclerosing panencephalitis (SSPE)

Typically, affected individuals develop mild, partial seizures before ten years of age. Epilepsia partialis continua is the form of epilepsy most commonly associated with Rasmussen's encephalitis. This form of epilepsy is characterized by a rapid, rhythmic succession of contractions and relaxations of a muscle or muscle group (clonus), particularly of the arms, legs, and face, that may occur singularly or in a repetitive, continuous series.

In most cases, affected children may exhibit progressive paralysis of one side of the body (hemiparesis) and/or mental retardation. 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 the brain and/or progressive confusion, disorientation, and/or deterioration of intellectual abilities (dementia).

The exact cause of Rasmussen's encephalitis is not known. Most researchers now suspect that Rasmussen's encephalitis is an autoimmune disorder since many patients have antibodies in their blood that bind to nerve cells and are capable of damaging the brain. In autoimmune disorders, the body's natural defenses (antibodies) fight the invading organisms and attack healthy tissue for no apparent reason.

Some researchers believe that Rasmussen's encephalitis may result from an unidentified viral infection such as influenza, measles, or cytomegalovirus. In some cases of Rasmussen's encephalitis, there has been an association with inflammation of the colored portion and the middle, blood vessel-containing layer of the eye (uveitis). Some researchers believe a primary ocular infection that may spread to the brain may result in Rasmussen's encephalitis.

Rasmussen's encephalitis mostly affects children ten years of age and younger. Adolescents and young adults in much smaller proportions are also affected. It appears that more females than males may be affected. It is probable that a few hundred cases may develop each year, although not all such cases may be properly identified.

Symptoms of the following disorder may be similar to Rasmussen's encephalitis. Comparisons may be useful for a differential diagnosis:

Subacute sclerosing panencephalitis (SSPE) is a progressive brain disorder usually occurring months to years after an attack of measles. It is characterized by mental deterioration, involuntary jerky movements, and seizures. This disorder usually becomes apparent before the age of 20 when an affected individual may begin to exhibit behavioral changes such as deteriorating performance of schoolwork and sluggishness. Such changes may be followed by additional symptoms and findings such as forgetfulness, temper outbursts, distractibility, sleeplessness, hallucinations, grand mal seizures, and/or sudden flexion movements of the extremities, head, and/or trunk. Symptoms often progress in severity. Possible complications may include coma. (For more information on subacute sclerosing panencephalitis, choose "Panencephalitis" as your search term in the Rare Disease Database.)

Diagnosis
Rasmussen's encephalitis may be diagnosed based upon a thorough clinical evaluation, a detailed patient history, and a complete neurological evaluation including advanced imaging techniques such as electroencephalography (EEG), computerized tomography (CT) scanning, or 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 CT scanning, a computer and x-rays are used to create a film showing cross-sectional images of the brain's tissue structure. During MRI, a magnetic field and radio waves are used to create cross-sectional images of the brain.

Treatment
Treatment of Rasmussen's encephalitis is 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.

More recently, surgery intended to control seizures, especially after the progression of the disorder has stopped, has become more common. The surgery involves either severing the nerves linking the two halves (hemispheres) of the cerebral cortex (functional hemispherectomy) or removing the affected hemisphere (hemispherectomy). Such surgery reduces, in most cases, the rate of recurrence of seizures as well as improving behavioral patterns and learning functions.

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 website.

For information about clinical trials being conducted at the National Institutes of Health (NIH) in Bethesda, MD, contact the NIH Patient Recruitment Office:

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

Recruitment for a clinical trial designed to study the safety , tolerability, and effectiveness of the drug rituximab for patients with Rasmussen's encephalitis (and chronic focal encephalitis) is supposed to begin soon. This clinical trial is being sponsored by the California Pacific Medical Center Research Institute in collaboration with the pharmaceutical company Genentech. The Identification Number of this clinical trial is: NCT00259805.

TEXTBOOKS
Beers MH, Berkow R., eds. The Merck Manual, 17th ed. Whitehouse Station, NJ: Merck Research Laboratories; 1999:1358.

Rowland LP. ed. Merritt’s Neurology. 10th ed. Lippincott Williams & Wilkins. Philadelphia, PA. 2000:666-67, 817..

Menkes JH, Pine Jr JW, et al. eds. Textbook of Child Neurology. 5th ed. Williams & Wilkins. Baltimore, MD; 1995:479-80, 749, 776.

RECENT JOURNAL ARTICLES
Koh S. Mathern GW, Glasser g, et al. Status ellipticus and frequent seizures: incidence and clinical characteristics in pediatric epilepsy surgery patients. Epilepsia. 2005;46:1950-54.

Korkman M, Granstrom ML, Kantola-Sorsa E, et al. Two-year follow-up of intelligence after pediatric epilepsy surgery. Pediatr Neurol. 2005;33:173-78.

Gaynor Y, Freilinger M, Dulac O, Levite M. Monozygotic twins discordant for epilepsy differ in the levels of pathogenic antibodies and cytokines. Autoimmunity. 2005;38:139-50.

Freeman JM. Rasmussen’s syndrome: progressive autoimmune multi-focal encephalopathy. Pediatr Neurol. 2005;32:295-99.

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.

Hart Y. Rasmussen’s encephalitis. Epileptic Disord. 2004;6:133-44.

FROM THE INTERNET
NINDS Rasmussen’s Encephalitis Information Page. Last updated January 25, 2006. 3pp.
www.ninds.nih.gov/disorders/rasmussen/rasmussen.htm

Hart I. Rasmussen’s Encephalitis. Encephalitis Information Resource. Last modified: 25/11/2005. 5pp.
www.encephalitis.info/TheIllness/TypesEncephalitis/Rasmussen.html