[Opsoclonic cerebellar disease. A paraneoplastic syndrome sensitive to chlormethiazole].

Opsoclonus is a very rare ocular dyskinesia associated to a viral infection or neoplasms, being neuroblastoma in children or carcinoma in adults. A case of opsoclonus as a paraneoplastic symptom preceding the diagnosis of breast carcinoma is presented. The abnormal movements had a complete response to the administration of chlormethiazole.