Dados do Trabalho

Título

Autoimmune encephalitis: how to recognize?

Resumo

Autoimmune encephalitis (AS) comprises a group of immune-mediated inflammatory diseases of the brain parenchyma, usually lasting less than 3 months. A monophasic course is common in AS by surface antibodies; a progressive course can occur in paraneoplastic encephalitis - such as paraneoplastic cerebellar degeneration (anti-Yo) -, hence the importance of screening for neoplasms. The objective is to elucidate diagnostic forms and the importance of a detailed history and physical examination in the management of these patients. After clinical suspicion, investigation with magnetic resonance imaging (MRI) of the brain and analysis of cerebrospinal fluid (CSF) is usually carried out. It is known that the presence of bilateral limbic encephalitis is the only isolated MRI finding that is sufficient for a definitive diagnosis, within the correct clinical context, even in the absence of measured antibodies. All other suggestive MRI patterns (cortical/subcortical, striatal, diencephalic, brainstem, encephalomyelitis, and meningoencephalitis) require antibody positivity. Furthermore, the electroencephalogram (EEG) provides evidence of focal or multifocal brain abnormality when MRI is negative. AS is the leading cause of refractory de novo status epilepticus (NORSE) and suggestive findings include focal deceleration/seizures and periodic lateralized discharges (Delta Brush). In addition, all patients with suspected AE require lumbar puncture (LP), unless contraindicated. In the analysis of the CSF, usually performed after MRI, the presentation of an inflammatory character may be the only abnormality found, serving as an indication for empirical immunotherapy, after ruling out infection. Common findings include: mild-to-moderate lymphocytic pleocytosis (commonly 20-200 cells, can be as high as 900 cells), hyperproteinorraquia, and sometimes an elevated IgG index. These findings, in the setting of negative infectious and oncotic cytology studies, support an immune-mediated etiology, but do not differentiate AS from other immune-mediated conditions, hence the need for clinical correlation. In addition, CSF and serum antinuclear antibody (NAA) testing and monitoring of the sodium level (showing hyponatremia in certain subtypes, such as LGI-1 antibody AS) may increase sensitivity. Thus, it is observed that the wide diagnostic approach and early identification are bases for diligent treatment, maximizing the chances of full recovery of the patient.

Palavras Chave

Immune-mediated diseases; Autoimmune encephalitis; Autoantibodies.