Trajectory of phantom limb pain relief using mirror therapy: Retrospective analysis of two studies

Background and purpose Research indicates that mirror therapy reduces phantom limb pain (PLP). Objectives were to determine when mirror therapy works in those who respond to treatment, the relevance of baseline PLP to when pain relief occurs, and what pain symptoms respond to mirror therapy. Methods Data from two independent cohorts with unilateral lower limb amputation were analyzed for this study (n = 33). Mirror therapy consisted of 15-min sessions in which amputees performed synchronous movements of the phantom and intact legs/feet. PLP was measured using a visual analogue scale and the Short-Form McGill Pain Questionnaire. Results The severity of PLP at the beginning of treatment predicted when pain relief occurred. Those with low baseline PLP experienced a reduction (p < 0.05) in PLP by session 7 of treatment, those with medium baseline PLP experienced pain relief by session 14 of treatment, and those with high baseline PLP experienced pain relief by session 21 of treatment. Mirror therapy reduced throbbing, shooting, stabbing, sharp, cramping, aching, tender, splitting, tiring/exhausting, and punishing-cruel pain symptoms. Conclusion The degree of PLP at baseline predicts when mirror therapy relieves pain. Implications This article indicates that the degree of baseline PLP affects when mirror therapy relieves pain: relief occurs by session 7 in patients with low PLP but by session 21 in patients with high PLP. Clinicians should anticipate slower pain relief in patients who begin treatment with high levels of pain. ClinicalTrials.gov numbers: NCT00623818 and NCT00662415.