Changes in thermal and mechanical pain thresholds in hand amputees. A clinical and physiological long-term follow-up

In a previous study, allodynia to cold and vibratory stimuli was found in the finger stumps of 24 patients with amputations, control values being obtained from fingers of the intact contralateral hand. When treated with regional intravenous guanethidine block (RGB), some of the patients only had short-lasting relief of symptoms, whereas others experienced a more long-lasting beneficial effect. In the present long-term follow-up study the patients were re-examined 6 years after the RGB treatment. The aim was to investigate whether the earlier symptoms and signs persisted, and whether there were any differences in these respects, between patients with long-lasting (group 1) and short-lasting relief of symptoms after RGB (group 2). All 24 patients were asked to answer a questionnaire concerning their clinical symptoms. In addition, 14 of them visited the laboratory for determination of thermal and vibration-induced pain thresholds. Comparisons were made with values obtained at the first examination before RGB treatment and with values from 14 healthy subjects tested in a similar way on 2 occasions with an interval of 8 years. Twenty of 23 patients reported that cold exposure still evoked stump pain. However, the threshold measurements showed that with time the patients had become more tolerant to thermal stimuli not only in the injured but also in the uninjured hand. A rise in pain threshold was also observed when vibration-induced pain was tested in the injured hand. There was no significant difference between groups 1 and 2. Similar changes in pain thresholds with time were not observed in the group of healthy control subjects.