Central Hypersensitivity in Chronic Hemiplegic Shoulder Pain

Soo Hoo J, Paul T, Chae J, Wilson RD: Central hypersensitivity in chronic hemiplegic shoulder pain. Am J Phys Med Rehabil 2013;92:1-13. Objective: This study aimed to examine the association of hemiplegic shoulder pain (HSP) with central hypersensitivity through pressure-pain thresholds (PPTs) in healthy, distant tissues. Design: This study is a cross-sectional study. A total of 40 patients (n = 20, HSP; n = 20, stroke without HSP) were enrolled in this study. PPTs were measured at the affected deltoid and the contralateral deltoid and the tibialis anterior using a handheld algometer. Differences in PPTs were analyzed by Wilcoxon's rank-sum test and with linear regression analysis, controlling for sex, a known confounder of PPTs. Results: The subjects with HSP had lower local PPTs than did the control subjects who have had a stroke when comparing the painful shoulders with the dominant shoulders of the controls and comparing the nonpainful shoulder and the tibialis anterior with the nondominant side of the controls. Similarly, those with HSP had lower PPTs compared with the controls in contralesional-to-contralesional comparisons as well as ipsilesional-to-ipsilesional comparisons. Conclusions: The subjects with HSP have lower local and distal PPTs than the subjects without HSP. This study suggests that chronic shoulder pain may be associated with widespread central hypersensitivity, which has been previously found to be associated with other chronic pain syndromes. This further understanding can then help develop better treatment options for those with this HSP.