Neurology India Medknow Publications on behalf of the Neurological Society of India ISSN: 0028-3886 EISSN: 1998-4022 Vol. 53, Num. 2, 2005, pp. 160-161

Neurology India, Vol. 53, No. 2, April-June, 2005, pp. 160-161

Invited Comments

Invited Comment

Bien C.G.

Department of Epileptology, University of Bonn, Bonn

Correspondence Address: Department of Epileptology, University of Bonn, Bonn, christian.bien@ukb.uni-bonn.de

Code Number: ni05046

Related article: ni05045. 

In this issue of Neurology India, Deb et al report on of a cohort of four patients with Rasmussen encephalitis (RE) from their center, admitted over a period of 3 years and all finally undergoing hemispherotomy.[1] Their report provides data on the neuropathology of brain tissue obtained on epilepsy surgery and also some clinical data. This is the first internationally accessible neuropathological RE series from India. Its results confirm earlier observations on RE mainly made in North America and Europe which can be summarized as follows: RE is a rare disease. It is estimated that major referral centers encounter one to two cases every year. The disease mainly affects children with a peak of incidence at the age of 6. It is a strictly unihemispheric brain disease characterized by a progressive cerebral hemiatrophy [visible on serial magnetic resonance imaging (MRI)], frequent one-sided simple partial motor (and other) seizures, often in the form of Epilepsia partialis continua, and progressive loss of unilateral neurological function. There is a maximum of disease activity during the first year after onset of the acute disease stage as evident from the high density of inflammatory cells observed in brain specimens, the rapid destruction of brain tissue and the loss of neurological and neuropsychological function during this period. Finally, the patients enter a residual stage with lower (but usually still high) seizure frequency, a stable, often severe neurological deficit and low-grade cerebral inflammation.[2],[3] Neuropathological studies have identified T cells and microglial cells as the main components of brain inflammation, and neurons as the targets of the inflammatory attack.[4],[5] By functional hemispherectomy or hemispherotomy, high-seizure freedom rates (80-85%) and low-complication rates have been achieved, however at the price of irreversible neurological deficits associated with the disconnected hemisphere.

These features are fairly constantly found in all patients described so far. This has led to a recent proposal of formal diagnostic criteria and the suggestion of a therapeutic pathway for RE patients.[6] From a practical point of view, the most urgent question regarding RE is now the following: What is the optimal treatment for patients in the early disease stage, i.e., with still rather well-preserved neurological deficits? Those patients are usually considered not to be eligible for hemispherectomy. They are, on the other hand, at high risk of developing severe neurological deficits. Immunosuppressive and immunomodulatory treatment regimens (steroids, intravenous immunoglobulins, plasma exchange, tacrolimus) are emerging as promising options for these patients. Early immunotreatment seems to be able to stop or slow down the progressive tissue and function loss. However, the optimal treatment still needs to be determined. Beyond this, the most challenging question is that regarding the cause of the inflammatory process. Is it indeed - as usually assumed - autoimmune in nature? Or does an infection with a so far unidentified agent trigger the immune process? Does the epilepsy as such contribute to or even initiate the chronic brain destruction? The answer to these questions may finally bring about an explanation for the most conspicuous and puzzling phenomenon of this disorder: the fact that it affects and destroys only one brain hemisphere.

To pursue these goals, future researchers will rely on a solid foundation of clinical and neuropathological data regarding this condition. Deb et al . should be credited with having broadened this foundation.

REFERENCES

1.	Deb P, Sharma MC, Gaikwad S, Tripathi M, Sharat Chandra P, Jain S, et al . Neuropathological spectrum of rasmussen encephalitis. Neurol India 2005;2:156-160.  Back to cited text no. 1    [BIOLINE]
2.	Robitaille Y. Neuropathologic aspects of chronic encephalitis. In: Andermann F, editor. Chronic encephalitis and epilepsy. Rasmussen's syndrome. Boston: Butterworth-Heinemann; 1991. p. 79-110.  Back to cited text no. 2
3.	Bien CG, Widman G, Urbach H, Sassen R, Kuczaty S, Wiestler OD et al . The natural history of Rasmussen's encephalitis. Brain 2002;125(Pt 8):1751-1759.  Back to cited text no. 3
4.	Bien CG, Bauer J, Deckwerth TL, Wiendl H, Deckert M, Wiestler OD et al . Destruction of neurons by cytotoxic T cells: a new pathogenic mechanism in Rasmussen's encephalitis. Ann Neurol 2002;51:311-18.  Back to cited text no. 4
5.	Pardo CA, Vining EP, Guo L, Skolasky RL, Carson BS, Freeman JM. The pathology of Rasmussen syndrome: stages of cortical involvement and neuropathological studies in 45 hemispherectomies. Epilepsia 2004;45:516-26.  Back to cited text no. 5
6.	Bien CG, Granata T, Antozzi C, Cross JH, Dulac O, Kurthen M et al . Pathogenesis, diagnosis and treatment of Rasmussen encephalitis: a European consensus statement. Brain 2005;128(Pt 3):454-71.  Back to cited text no. 6

Copyright 2005 - Neurology India