Paraneoplastic neurological syndromes (PNS) a ff ecting the central nervous system are infrequent, presenting in < 1% of all those with cancer. The relevant auto-antibodies, that are detected in serum or cerebrospinal fl uid, can target either neuronal cytoplasmic/nuclear proteins or neuronal cell surface proteins such as ion channels. The type of antibodies detected may determine the underlying malignancy and also response to immunotherapy. Anti-CV2/CRMP-5 is a 62-kDa neuronal cytoplasmic protein of the collapsin response-mediator family that is usually correlated with thy- moma or small cell lung cancer (SCLC). The PNS associated with anti- CV2/CRMP-5 is generally characterized by encephalomyelitis, para- neoplastic sensory neuronopathy, uveitis or chorea [ 1 ]. We have re- cently encountered a patient with prominent motor weakness and be- havioral changes whose cranial MR investigation was compatible with striatal encephalitis and spinal MR imaging revealed longitudinal myelitis. Paraneoplastic antibody screening was positive for anti-CV2/ CRMP-5 antibodies. Meticulous workup disclosed small cell lung cancer (SCLC) as the underlying pathology
