CDR2 and pathologic nystagmus: However, the persistence and progression of the remaining symptoms, with the appearance of objective cerebellar signs (axial ataxia, dysarthria, nystagmus), in a more complex clinical pattern inconsistent with exclusive pharmacological toxicity, was fundamental in raising the hypothesis of an immune-mediated neurological process, later confirmed by the positivity of anti-Yo antibodies. Concurrent positivity for anti-Yo and anti-amphiphysin antibodies is uncommon, as most published studies describe anti-Yo reactivity alone in cases of paraneoplastic cerebellar degeneration [2,4].