Concordance of Phantom and Residual Limb Pain Phenotypes in Double Amputees: Evidence for the Contribution of Distinct and Common Individual Factors.

UNLABELLED: Most, but not all, limb amputees develop phantom limb pain (PLP) or residual limb pain (RLP), and large interindividual differences in pain intensity and course are apparent. The present cross-sectional study of 122 double amputees investigated the possible role of genetic factors in PLP and RLP, assuming that strong individual predisposition results in high intraindividual concordance in pain phenotype. Intraindividual concordance was observed in 116 (95%) patients for development of PLP and in 110 patients (90%) for development of RLP. For both pain types, high intraindividual concordance was also observed for remission and current intensity. Moderate association for lifetime history and current intensity of PLP and RLP was observed both within and between limbs. The high intraindividual concordance in pain phenotypes suggests strong individual predisposition for PLP and RLP development. However, the finding of only moderate association between PLP and RLP suggests that susceptibility to these pain phenomena involves distinct, as well as common, risk factors. Genome-wide studies in large samples of single amputees may facilitate the dissection of these phenotypes and their underlying mechanisms. PERSPECTIVE: The observation of high intraindividual concordance for PLP and RLP in 122 double amputees suggests that individual factors contribute to post-amputation pain. The relatively low intraindividual association between PLP and RLP suggests that these factors are at least partially specific for each pain type.