Autoimmune encephalitis: the new hit at neurological parade

Abstract

R ecently, we have witnessed the fast growth of knowledge in neurology, particularly within neuroimmunology. Also, old neurological diseases have been revisited and renamed with the emerging class of anti-neural antibodies (AN-Ab). At the same time, neurologists have become aware of diagnosing immune-mediated diseases and understanding their immunological mechanisms. Different lines of research have uncovered that peripheral and central nervous tissues are not immune-privileged sites, which used to be thought due to their biological barriers.Independently of terminology 1,2, we should bear in mind that autoimmune encephalitis (AIE) is a generic term that encompasses more than paraneoplastic and non-paraneoplastic diseases or conditions linked to AN-Ab. For instance, Machado et al. 3 , in this issue of Arquivos de Neuropsiquiatria, and other classical revisions 3-8 have shown that not only the neurological manifestations are shared by other more common neurological diseases, but also one specific AN-Ab is associated with clinical heterogeneity and distinct neurological prognosis.Unquestionably, the AN-Ab discovery has contributed for our understanding of AIE pathogenic process 9,10 , and can point to a more specific treatment in near future. However, we should deal with some issues. For example, the infectious diseases are highly prevalent, these new AN-Ab laboratorial tests are not easily and routinely available in public health system (even at university centers), the costs of them privately held are very expensive ($ 1,000-2,000/Ab/ sample), their results take at least 20 days to be released, even privately held or kindly given by doctor Dalmau (problematic when we are face to a case of acute onset), the AN-Ab negative results do not exclude AIE diagnosis, and some medicines used abroad have restrictive practices, such as monoclonal antibodies in Brazil.Considering literature data, the previous paragraph, and our own service experience, it can be noted that AIE could be diagnosed and treated without any AN-Ab tests. In a more chronic presentation (more than six months 7 ) at first neurological evaluation, all steps presented by Machado et al. should be followed, and the immunotherapy should be started as soon as the more common diseases have been ruled out.The major concern is represented by acute/sub-acute onset (less than six weeks 2