Central nervous system autoimmune syndrome associated with neuronal surface antibodies in the course of Enterovirus encephalitis

Case Report: In the past years CNS syndromes associated with antibodies against neuronal surfaces (NSAS) have been further characterized (e.g., N-methyl-d-aspartate receptor antibody encephalitis, limbic encephalitis). There is evidence that autoimmune forms of encephalitis benefit from an early immunomodulatory intervention with a chance of substantial recovery. On the other hand, there are several well-described pediatric CNS syndromes (e.g., postinfectious cerebellitis) with clinical evidence of being immune mediated, without defined pathogenic antibodies, that tend to improve spontaneously.

Case Report: We report a case of a previously healthy 13-year-old girl with chronic inflammatory cerebellitis following an acute Enterovirus encephalitis. She recovered from acute disease with a persistent ataxia and a cerebellar atrophy. Her symptoms progressively worsened and after a few months she developed seizures, behavioral changes, and neuropsychological deficits. MRI revealed progressive cerebellar atrophy. One year after the initial presentation, CSF showed a persistent increase in the IgG index and positive oligoclonal IgG bands. With indirect immunofluorescence neuronal surface antibodies (neuropil) were detected. Tumor search did not reveal an underlying neoplasm. Due to the assumption of an autoimmune cerebellitis with antibodies to a neuronal surface antigen, the girl was started on an intense immune modulatory therapy (corticosteroids and immunoabsorption).

Conclusion: In this case of a juvenile postinfectious chronic inflammatory cerebellar ataxia in the course of an E. encephalitis, we found both clinical evidence and neuropil antibodies suggesting an autoimmune mechanism that justified the start of an intense immunomodulatory therapy. In suspected possible NSAS immunotherapy should be considered early in the course, as these conditions might be responsive to treatment. To identify patients that will benefit from immunomodulatory therapy, a guideline is needed that involves clinical and paraclinical features.