Efficacy of Mirror Therapy in Patients with Phantom Pain after Amputation of a Lower Limb: A Systematic Literature Review

Background Up to 80% of patients after amputation are affected by phantom limb pain. This may be due to various mechanisms of cortical reorganisation. Non-surgical treatment of the neuropathic phantom limb pain involves mirror therapy. Thereby, the use of a mirror should induce the illusion that the extremity has been preserved. This illusion should initiate processes to restore the original organisation of the somatosensory and motor cortex and thus to reduce pain. Evidence of mirror therapy to treat lower extremity phantom limb pain is rare. Therefore, the aim of this systematic review is to qualitatively analyse the efficacy of mirror therapy for treatment of phantom limb pain in adult patients after unilateral amputations of the lower extremity. Method The databases Medline (PubMed), Physiotherapy Evidence Database (PEDro), Cochrane Library (Central), and OPENGREY were systematically searched until 26th November 2020, followed by continued searches in these databases to provide a review of updated literature. Study selection, data extraction, and risk of bias evaluation (Risk of Bias Tool [RoB]) of included studies were conducted by two reviewers independently. The primary outcome was pain intensity, and secondary outcomes were pain frequency, pain duration, activities of daily life (ADL), and quality of life. The methodology of this review follows the recommendations of Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) and the Cochrane Handbook for Systematic Reviews of Interventions. Results The search revealed 234 articles. Four articles were included in the analysis. A reduction in pain intensity due to mirror therapy was reported in all studies, however, in only 2 studies there were significant differences between mirror therapy and the comparison after 4 weeks of treatment (p < 0.001; p < 0.05). This significant difference was maintained after 3 and 6 months follow-up in one of those studies (p < 0.001). The outcomes pain frequency, pain duration, and ADL were decreased after 4 and 10 weeks of mirror therapy compared to comparison, but with no statistical significance (p > 0.05). After 6 months, there was a significant improvement in the duration of pain and in ADL after mirror therapy compared with the control group (p < 0.05). Differences in the results quality of life between the intervention group and comparison were observed in 2 studies. Conclusion Mirror therapy of high frequency and duration is an effective intervention to reduce phantom limb pain in patients after unilateral lower extremity amputation. The superiority of mirror therapy to other interventions cannot be concluded, as the evidence was of low quality.