Pain in Parkinson's disease.

Three patients are described who suffered from Parkinson's disease and who also experienced severe pain. In one patient who had used psychotropic medication for a long period there was evidence of associated autonomic failure. It is suggested that the pain, which has some features of central pain with ill defined areas of involvement and lack of sensory abnormality, may occasionally be an important aspect of Parkinson's disease and indeed can precede the onset of this extrapyramidal disorder. Possible mechanisms are discussed including the influence of dopaminergic pathways on pain modulation. The importance of recognising the pain of Parkinson's disease is stressed.