Painful Parkinson's disease.

A number of patients with Parkinson's disease complain of severe and distressing pain. Many of them are referred for psychiatric or other inappropriate treatment. The key diagnostic clue to the origin of the pain is that in almost all cases it fluctuates in parallel with the motor changes associated with levodopa treatment. The nature of this temporal association in the individual case, as well as aiding diagnosis, often indicates the need for appropriate modifications in antiparkinsonian therapy, which can be far more effective than conventional analgesic treatments.