Rasmussen’s Encephalitis: Incidence and Response to Treatment with Tacrolimus or Intravenous Immunoglobulins

In Epilepsia early view on-line version ahead of press dated December 2012, Drs. Bien and colleagues from the Department of Epileptology, University of Bonn Medical Center in Bonn, Germany, and a number of other centers throughout Germany, present an interesting and important analysis assessing the frequency of Rasmussen's encephalitis and its response to immune based therapy. Rasmussen's encephalitis is an immune based condition characterized by serious uncontrolled seizures. This study was the first randomized, prospective treatment trial in Rasmussen's encephalitis assessing how individuals perform with regards to tacrolimus versus intravenous immunoglobulin. The researchers set out to establish outcomes defined as a loss of motor function, and/or changes in hemispheric volume using a historical control group.

Over 6.3 years, 21 patients with recent-onset Rasmussen's encephalitis were found. Sixteen were randomized to tacrolimus ( n = 9) versus IVIG, (n = 7). Immunotreated patients had a longer survival than the historical control. Neither treatment group was more effective than the other. Two patients who had been treated with tacrolimus experienced serious adverse effects. No immunotreated, but several untreated patients, developed intractable epilepsy. No patients with refractory epilepsy became treatment responsive under immunotherapy.

The authors found that the incident rate of diagnosed Rasmussen's encephalitis is 2.4 cases per 107 people in individuals less than the age of 18 years of age. Tacrolimus or IVIG may slow down tissue and function loss and prevent the development of drug-resistant epilepsy. However, immunotherapy may arrest patients in a state of pharmacoresistant epilepsy without allowing the disease to progress. Moreover, the study did not make clear how immune treatments compare to surgery (i.e. hemispherectomy).

Rasmussen's encephalitis, although rare, is very difficult to manage and very little is known with regards to the best treatment approach in these individuals. The study helps to suggest that immune treatment may help over the long run with regards to stabilizing the condition, but it does not necessarily cure the epilepsy or make drug-resistant epilepsy responsive.