Paraneoplastic cerebellar syndrome and optic neuritis with anti-CV2 antibodies: clinical response to excision of the primary tumor.

OBJECTIVE To describe a patient with a paraneoplastic cerebellar syndrome and optic neuritis with circulating anti-CV2 antibodies and clinical improvement after excision of a small cell lung carcinoma. DESIGN Report of a case. SETTING A 62-year-old man simultaneously developed a severe cerebellar syndrome and a bilateral optic neuritis predominantly in the left eye (visual acuity, 20/25 in the right eye; < 20/400 in the left eye; and bilateral swelling of the optic discs). MAIN OUTCOME AND RESULTS Anti-CV2 antibodies, recently described as associated with paraneoplastic neurological syndrome, were detected in the patient's serum sample. These antibodies were demonstrated to react with the cytoplasm of a subpopulation of oligodendrocytes in the white matter of rat brain in the cerebellum, brainstem, spinal cord, and optic chiasm. The patient was found to have a small cell lung carcinoma, which was removed. After excision of the tumor, the cerebellar syndrome improved dramatically and the papilledema disappeared despite aftereffects of the optic neuritis. CONCLUSIONS These findings were consistent with the diagnosis of a paraneoplastic neurological syndrome, although both optic neuritis and remission of the cerebellar syndrome are uncommon patterns of paraneoplastic syndromes. CV2 antigen expression by the oligodendrocytes of the cerebellum, brainstem, spinal cord, and optic chiasm correlated with the clinical syndrome observed in our patient. However, the precise pathophysiological role of anti-CV2 antibodies is still unknown.