[Clinical presentation of immune mediated cerebellar ataxia]

Over the last decades, clinical evidence has accumulated indicating that the immune system may play an important role in some central nervous system diseases usually regarded as degenerative. The best known example is paraneoplastic cerebellar ataxia (PCA), which is thought to involve autoimmune cross-reaction between tumor and nervous system antigens. In the past twenty years, several antibodies directed against neuronal and tumor antigens have been described in association with PCA, leading to the description of different subtypes of PCA depending on the associated antibodies, the clinical course and the type of tumor. In some types, cerebellar ataxia occurs alone, whereas, in others, it is only one clinical feature in the setting of extensive nervous system disease. Circulating antibodies have also been described in patients with non-paraneoplastic cerebellar ataxia (N-PCA), suggesting that the immune system may be involved in certain cases of sporadic cerebellar ataxia. In this review, the clinical presentation of the different subtypes of potentially immune-mediated PCA and N-PCA will be described, and the experimental approaches developed in order to understand the pathogenic importance of the immune system in these ataxias will be discussed.