Differences in pain perception and sensory discrimination between chronic low back pain patients and healthy controls.

Pain perception threshold (PPT), maximal pain tolerance (MPT) and pain discrimination of CLBP patients and controls were tested. Pain perception threshold was significantly higher in the patient group for two different pain stimuli (electrical and pressure pain). Maximal pain tolerance was significantly higher in CLBP patients only for the pressure pain stimulus. There was no difference between the groups in their capacity to discriminate between painful stimuli of different intensity, as measured by a forced-choice task. It is concluded that CLBP patients have a decreased sensitivity for experimental pain. Two theories which might explain this decreased sensitivity are discussed.