What is Rasmussen's encephalitis

Rasmussen's encephalitis is a rare, chronic inflammatory brain disorder characterized by frequent, severe seizures, progressive loss of neurological function, and inflammation in one hemisphere of the brain. It primarily affects children and often results in permanent cognitive and physical deficits if not managed with aggressive intervention.

What causes Rasmussen's encephalitis?

While the exact trigger remains a subject of ongoing research, Rasmussen's encephalitis is widely considered an autoimmune-mediated process. The body’s immune system mistakenly attacks its own brain cells, leading to chronic inflammation and the destruction of neurons and glial cells. This localized inflammation causes the affected hemisphere to shrink (atrophy) over time, which is why Rasmussen's encephalitis is sometimes referred to as a progressive hemispheric syndrome.

Who is typically affected by Rasmussen's encephalitis?

Rasmussen's encephalitis is an exceptionally rare condition, with an estimated annual incidence of approximately 2 cases per 10 million people. It primarily affects children, with the average age of onset falling between 6 and 8 years old, though it can occasionally manifest in adolescents or adults. There is no significant gender bias or geographic clustering identified in the literature, and it is generally not considered an inherited genetic condition.

What are the primary clinical features?

The progression of Rasmussen's encephalitis typically follows a predictable, albeit devastating, clinical course:

• Prodromal stage: Often presents with mild, infrequent seizures or occasional weakness.


• Acute stage: Characterized by frequent, drug-resistant seizures (often epilepsia partialis continua), rapid cognitive decline, and progressive paralysis on the side of the body opposite the affected brain hemisphere.


• Residual stage: Seizure frequency may stabilize, but the patient is typically left with permanent motor deficits and cognitive impairment.

How is Rasmussen's encephalitis distinct from other epilepsies?

Unlike common childhood epilepsies, Rasmussen's encephalitis is defined by its progressive, inflammatory nature. While standard anti-seizure medications often fail to control the symptoms of Rasmussen's encephalitis, surgical interventions—such as a functional hemispherectomy—are frequently considered to halt the progression of the disease and improve long-term outcomes.

Next steps

• Consult a pediatric neurologist or an epileptologist specializing in inflammatory brain diseases.


• Connect with the 14 community members on DiseaseMaps.org who have shared their experiences with Rasmussen's encephalitis.


• Request specialized neuroimaging (MRI) to monitor for hemispheric atrophy.

Medical disclaimer: This content is for informational purposes only and does not constitute professional medical advice, diagnosis, or treatment.

References

• NIH Genetic and Rare Diseases Information Center (GARD)


• Orphanet: Rare Disease Database (ORPHA:765)


• OMIM (Online Mendelian Inheritance in Man): Rasmussen Encephalitis


• The Rasmussen’s Encephalitis Patient Support Group and clinical literature via PubMed