Paraneoplastic neurological syndromes are rare syndromes caused by the remote effects of cancer. They have an immune-mediated pathogenesis, yet the underlying mechanisms are not fully elucidated. CV2/Collapsin response-mediator protein 5 (CRMP5)-IgG paraneoplastic neurological syndrome is characterized by heterogeneous clinical presentations, affecting both central and peripheral nervous system, and the most frequently associate tumor is small cell lung carcinoma. Central nervous system involvement along with CSF and neuroimaging findings have not been fully described in the literature in CV2/CRMP5 patients. Unraveling the complexities of CV2/CRMP5 paraneoplastic neurological syndrome is critical to improve diagnosis, treatment, and patients' care. Our intention is to perform a comprehensive analysis of the clinical characteristics and instrumental investigations of a large cohort of CV2/CRMP5 patients.

Inclusion Criteria:

• Patient with paraneoplastic neurological syndromes
• Patient with CV2 antibody in sera and/or CSF

Exclusion Criteria:

• Patient with no data
• Patient without neurological disorder
• Patient without CV2 antibody in sera/CSF

Patients harboring CV2 Abs in serum and/or CSF with or without cancer.