The influence of preamputation pain on postamputation stump and phantom pain

The significance of preamputation pain for the development of postamputation stump and phantom pain has been discussed over the years and is still a matter of dispute. It has been argued that preamputation pain increases the risk of phantom pain and that phantom pain is a revivification of pain experienced before the amputation. The purpose of this prospective study was to clarify the relation between preamputation pain and phantom pain. Fifty-six patients scheduled for amputation of a lower limb were interviewed the day before the amputation about preamputation pain and about stump and phantom pain 1 week, 3 and 6 months after the amputation. Pain was quantitated and described using a visual analogue scale (VAS), 10 different word descriptors, the McGill Pain Questionnaire (MPQ) and the patients' own words. If phantom pain was present patients were asked if the pain was similar to any pain experienced before the amputation. At each postoperative interview patients were asked to recall preamputation pain intensity. Location of pain and analgesic requirements were registered. Preamputation pain significantly increased the incidence of stump pain (P = 0.04) and phantom pain (P = 0.04) after 1 week and the incidence of phantom pain after 3 months (P = 0.03). About 42% of the patients reported that their phantom pain resembled the pain they had experienced at the time of the amputation. However, there was no relation between the patients' own opinion about similarity between preamputation pain and phantom pain and the actual similarity found when comparing pre- and postoperative recordings of pain. Patients significantly overestimated preamputation pain intensity after 6 months.