Autoimmune Ataxias

The dramatic progress in the genetic characterization of the numerous forms of ataxias, using next-generation sequencing (NGS) and whole genome sequencing (WGS), has also revealed that a substantial number of sporadic ataxias are not due to genetic defects but are likely to be immune-mediated for a proportion of them. At the same time, the recent identification of an increasing number of antibodies associated with sporadic ataxias has clarified the diagnostic approach for immune-mediated cerebellar ataxias (IMCAs). However, the diagnosis of IMCA remains problematic if it is solely dependent on the serological screening for such antibodies. Moreover, there is a significant phenotypic overlap with non-immune forms of ataxia. In the majority of cases, serological screening for known antibodies associated with IMCA may not be readily available. In other conditions, no specific antigenic trigger or associated antibodies have been identified so far. Therefore, recognition of IMCA relies on clinical expertise, indirect evidence of autoimmunity (additional autoimmune diseases or family history of autoimmune disease), and appropriate investigations. It is imperative to consolidate quickly such a diagnosis as therapeutic interventions can be effective in salvaging cerebellar reserve.