Pain relief by movement representation strategies: An umbrella and mapping review with meta-meta-analysis of motor imagery, action observation and mirror therapy

Objective To develop a mapping and umbrella review with a meta-meta-analysis (MMA) to critically evaluate the current evidence of motor imagery (MI), action observation and mirror therapy (MT) on pain intensity. Methods The study involved a systematic search of PubMed, PEDro, Scielo, EBSCO and Google Scholar. Results Ten systematic reviews were included in the qualitative synthesis, 70% of which showed high methodological quality. Three reviews found a significant reduction in chronic musculoskeletal pain as the result of applying movement representation methods (MRM) plus usual-care (UC), with a large clinical effect (standardized mean difference [SMD] of -1.47; 95% CI -2.05 to -0.88; heterogeneity Q = 1.66; p = 0.44; I-2 = 0%). However, two reviews showed no statistically significant reduction in acute and postsurgical pain as a result of applying MI plus UC. Four reviews showed no significant reduction in phantom limb pain (PLP) as a result of applying MT plus UC interventions. In four reviews, the MMA showed a significant reduction in complex regional pain syndrome (CRPS) as a result of applying MT plus UC, with a large clinical effect (SMD -1.27; 95% CI -1.87 to -0.67; heterogeneity Q = 3.95; p = 0.27; I-2 = 24%). In two reviews, the MMA showed no significant differences in poststroke pain as a result of applying MT plus UC. Conclusion Results show that MRM could be effective for chronic musculoskeletal pain, with low to moderate-quality evidence. The results also show a reduction in pain intensity through MT interventions in patients with CRPS, although these results were not found in patients with PLP or poststroke pain. Significance This umbrella review analysed systematic reviews evaluating movement representation techniques, with the aim of synthesizing the available evidence regarding motor imagery, action observation and mirror therapy on pain. The results provide relevant information about the potential clinical use of movement representation techniques in different types of patients with painful conditions.