Mechanical hyperesthesia and cold perception hypoesthesia in distal residual limbs of amputees

Abstract

In this prospective study, we report that the distal residual limbs (DRL) of amputee subjects are hyperesthetic/allodynic for pressure pain thresholds (large fibers) and hypoesthetic for cold perception threshold (small fibers) in comparison with the contralateral unaffected extremities. We prospectively assessed twenty-two subjects (18 with pain, 4 without) with a unilateral upper or lower limb amputation. We utilized the Fischer algometer to compare pressure pain thresholds (PPT) and the Medoc peltier type device to compare thermal perception thresholds. The Wilcoxon Signed Rank Test was used to analyze the affected limb versus the unaffected limb of these psychophysical tests. Our results revealed decreased perceptual threshold values for pressure pain threshold(p <0.016) and an elevated threshold for cold perception (p<0.017) There were no significant difference in thresholds for cold pain or hot perception or pain. There were no differences detected between subjects with and without pain. These results suggest a possible peripheral pathological processes in superficial tissue of the residual limb, such as a differential dying back phenomena of small (cold perception) or peripheral sensitization of large fiber output; or a central phenomena such as sensitization or disinhibition.