Exploring the diverse phenotypes of anti-GAD 65 encephalitis, diagnosis and treatment challenges

Objectives. To present two cases of anti-glutamic acid decarboxylase 65 (anti-GAD65) antibody encephalitis with different clinical phenotypes. Introduction. Anti-glutamic acid decarboxylase 65 antibody encephalitis (GAD-65 AE) is a rare pathology with a high potential for severity, having multiple forms of presentation and multiple differential diagnoses. This presentation aims to exemplify the strong clinical heterogeneity that is associated with this clinical entity by putting forth two cases that were treated in our clinic, each representing a separate clinical phenotype of this pathology. Material and methods. We analyzed two cases from our clinic of autoimmune encephalitis with positive anti-GAD65 antibodies and compared the cases with the data from the literature regarding clinical presentation, differential diagnosis, treatment, and evolution. Content. The first case presented is a woman aged 71 (66 at onset) presenting with progressive cerebellar ataxia. She was diagnosed with GAD-65 AE based on clinical presentation and positive anti-GAD65 antibodies titer. She was initially treated with methylprednisolone pulse therapy and received four such courses in the first year afte