Changes in pain perception after treatment for chronic pain.

Pain threshold, sensitivity, response bias and ability to discriminate were measured before and after treatment for 15 improved and 15 unimproved chronic pain patients diagnosed as having myofascial pain dysfunction (MPD) syndrome, There were no differences between the groups before treatment. After treatment, the improved group showed an increase in pain threshold, sensitivity and ability to discriminate between different levels of painful stimulation and a decrease in response bias to report pain. The unimproved group showed no changes.