Autoimmune cerebellar ataxia: An overlooked, but treatable, neuroimmune condition

Abstract Autoimmune cerebellar ataxia (ACA) is a condition in which the cerebellum is the primary location of inflammation due to autoimmune encephalitis caused by neuroimmune conditions. Although ACA is rare, it remains an important differential diagnosis, distinct from other neurodegenerative conditions, such as multiple system atrophy. An accurate diagnosis requires the integration of clinical history, blood tests, cerebrospinal fluid analysis, magnetic resonance imaging and malignancy screening. Over 30 neural antibodies associated with ACA have been reported as diagnostic biomarkers. The clinical profile of frequently reported antibodies, such as anti‐Yo and anti‐GAD, are well‐defined, although that of rarer antibodies remain unclear. Cell‐based assays are the standard method for detecting most neural antibodies, but testing for a wide range of antibodies is costly. Immunoblots assays and tissue‐based assays are useful for screening. Further investigations into clinical profiles and advancements in screening methods are required to identify neural antibodies. ACA should not be overlooked, due to its treatable nature. Acute phase treatments, such as intravenous methylprednisolone and immunoglobulin, plasma exchange, and rituximab, are effective. Maintenance therapy using steroids and/or immunosuppressants is used to prevent relapse and progression. However, maintenance therapy requires individualized decisions due to limited clinical evidence. Additionally, treatment responses might vary depending on the type of neural antibody. In the future, the development of biomarkers and improved autoantibody testing methods is important to develop novel therapies and optimal immunotherapy for patients with ACA.