Cognitive-emotional sensitization contributes to wind-up-like pain in phantom limb pain patients.

Peripheral mechanisms are known to play a role in phantom pain following limb amputation, and more recently it has been suggested that central mechanisms may also be of importance. Some patients seem to have a psychological sensitivity that predisposes them to react with pain catastrophizing after amputation of a limb, and this coping style may contribute to increased facilitation, impaired modulation of nociceptive signals, or both. To investigate how pain catastrophizing, independently of anxiety and depression, may contribute to phantom limb pain and to alterations in pain processing twenty-four upper-limb amputees with various levels of phantom limb pain were included in the study. Patients' level of pain catastrophizing, anxiety and depression was assessed and they went through quantitative sensory testing (QST) of thresholds (mechanical and thermal) and wind-up-like pain (brush and pinprick). Catastrophizing accounted for 35% of the variance in phantom limb pain (p=0.001) independently of anxiety and depression. Catastrophizing was also positively associated with wind-up-like pain in non-medicated patients (p=0.015), but not to pain thresholds. These findings suggest that cognitive-emotional sensitization contributes to the altered nociceptive processing seen in phantom limb pain patients. The possible interactions between pain catastrophizing, wind-up-like pain, and peripheral input in generating and maintaining phantom limb pain are discussed.