Paraneoplastic neurological disorders

A paraneoplastic neurological disorder (PND) may be defined as one in which a particular neoplasm associates with a remote but specific effect on the nervous system more frequently than would be expected by chance1. The range of tumours that can provoke these disorders is relatively limited. The commonest is small cell lung tumour, where a prospective study of 150 cases detected a paraneoplastic disorder in about 3%.This would imply that about 250 new cases a year in the UK are associated with this neoplasm, but in practice it seems that the diagnosis is often overlooked. Other neoplasms commonly implicated in PND are ovarian and breast cancers, neuroblastoma, thymoma and lymphoma. Diagnosis is often hampered by the fact that in most cases the onset of the neurological syndrome precedes the cancer declaring itself, sometimes for as long as five years.