Effect of one session of mirror therapy on phantom limb pain and recognition of limb laterality in military traumatic lower limb amputees: a pilot study

Abstract

Up to 70 % of military amputees suffer phantom limb pain (PLP), which is difficult to treat. PLP has been attributed to cortical reorganisation and associated with impaired laterality. Repeated sessions of mirror therapy (MT) can benefit PLP; however, anecdotal evidence suggests one MT session could be effective. In a one-group pretest and post-test design, 16 UK military unilateral lower limb amputees (median age: 31.0, 95% CI 25.0 to 36.8 years) undertook one 10 min MT session. Visual analogue scale (VAS) pain and laterality (accuracy and reaction time) measurements were taken pre-MT and post-MT. Median VAS PLP did not differ significantly between pre-MT 15 mm (2–53 mm) and post-MT 12 mm (1–31) (p=0.875) scores. For the amputated limb, there were no significant differences between pre-MT and post-MT scores for laterality accuracy, 95.3%, 95% CI 90.5% to 97.6% and 96.7%, 95% CI 90.0% to 99.4%, respectively (p=0.778), or reaction time, 1.42 s, 95% CI 1.11 to 2.11 s and 1.42 s, 95% CI 1.08 to 2.02 s, respectively (p=0.629). Laterality was also not different between limbs for accuracy, p=0.484, or reaction time, p=0.716, and did not correlate with PLP severity. No confounding variables predicted individual responses to MT. Therefore, one 10 min MT session does not affect laterality and is not effective as standard treatment for PLP in military lower limb amputees. However, substantial PLP improvement for one individual and resolution of a stuck phantom limb for another infers that MT may benefit specific patients. No correlation found between PLP and laterality implies associated cortical reorganisation may not be the main driver for PLP. Further research, including neuroimaging, is needed to help clinicians effectively target PLP.