Acquisition of chronic pain

It is suggested that psychophysiological mechanisms play an important role in the development and maintenance of chronic pain states. There is accumulating evidence that chronic pain patients show learnt increases in muscles tension when exposed to stressful and painful events. Muscle tension increases can be classically conditioned in healthy humans, but are acquired more rapidly in a subchronic pain group at high risk for chronicity. Conditioning leads to the formation of memories for pain that alter the central processing of stimuli in chronic pain patients. Initial analyses of the cortical processing of painful and nonpainful stimulation in chronic pain patients confirm this hypothesis. Specifically, increased cortical reactivity to painful tactile stimulation was detected. In phantom pain patients hyperreactivity of somatosensory cortical areas representing body parts adjacent to the site of the lesion was observed. To what extent the peripheral and central physiological abnormalities are related remains to be determined. The authors propose that both central and peripheral psychophysiological response stereotypes are present in chronic pain patients and discuss their potential role in the chronification process.