Does Upper Limb Pain Affect the Left/Right Judgment Task? A Systematic Review and Meta-analysis

Abstract

Objective: An emerging body of evidence suggests an association between pain and altered neural representations of the body. The integrity of these neural representations can be assessed with a timed motor imagery task such as the left/right judgment task (LRJT). The purpose of this investigation was to systematically evaluate the literature and use meta-analytical methods to establish whether performance of the LRJT is impaired in people with upper limb pain. Materials and Methods: The literature was systematically searched across 8 databases for studies that reported use of the LRJT and also reported upper limb pain. Fifteen studies were found that included 6 upper limb pain conditions and 749 participants. Studies were grouped into 2 categories: (1) studies that compared response time and accuracy with healthy controls (between group comparison) and (2) studies that compared response time and accuracy for affected limb with the subject’s healthy limb (within group comparison). Data were pooled, mean effect size calculated, and forest plots produced using RevMan 5.5. Results: Response times were slower in people with upper limb pain when compared with healthy controls (effect size: 1.42; 95% CI, 0.54 to 2.30). The pain group were also slower in identifying images corresponding to their painful limb than their healthy limb (effect size: 0.71; 95% CI, 0.24 to 1.17). Accuracy was reduced in people with upper limb pain compared with healthy controls (effect size: −0.76; 95% CI, −1.17 to −0.35). The pain group were also less accurate identifying images corresponding to their painful limb compared with the healthy limb (effect size: −0.63; 95% CI, −1.21 to −0.06). Conclusions: The findings of this meta-analysis and synthesis suggest that performance of the LRJT is impaired in people with upper limb pain conditions. Response times (RTs) are slower and accuracy is worse than healthy control subjects or healthy limbs. This reflects disturbances in cortical motor imagery processing and may indicate cortical changes associated with upper limb pain.