A randomized, controlled trial of mirror therapy among men with unilateral upper-limb amputations and phantom limb pain (PLP) was conducted with participants from Walter Reed National Military Medical Center, Bethesda, Maryland, and Brooke Army Medical Center, San Antonio. The results of the trial, published July 7 in Frontiers in Neurology, indicated that mirror therapy reduced the severity and duration of daily PLP episodes in this population.
The 15 participants were randomly assigned to one of two groups: mirror therapy (n = 9) or control (n = 6, covered mirror or mental visualization therapy). Participants were asked to perform 15 minutes of their assigned therapy daily for five days per week for four weeks. The primary outcome measure was pain, as measured with a 100mm visual analog scale.
The results indicated that subjects in the mirror therapy group had a significant decrease in pain scores, from a mean of 44.1mm (SD = 17) to 27.5mm (SD = 17.2). In addition, there was a significant decrease in daily time in which they experienced pain, from a mean of 1,022 minutes (SD = 673) to 448 minutes (SD = 565). By contrast, the control group had neither diminished pain nor decreased overall time experiencing pain.
A decrease in pain response seen by the tenth treatment session was predictive of final efficacy. Each participant’s response to mirror therapy after five sessions was largely predictive of the response at four weeks. Six participants (66.7 percent) reported a directional change in their pain scores at the day five assessment that was consistent with their directional change after four weeks. Of the three remaining subjects, all reported a directional change at the day ten assessment that agreed with that of their day 20 assessment. Five of the six patients in the control group crossed over and completed four weeks of mirror therapy. They all then had decreased pain severity as well as time experiencing pain.
The authors note, however, that the participant population consisted only of men, which precludes generalizing the findings, as literature supports pain perception and pain thresholds differing between the sexes. Another limitation of the study is that, due to the small sample size, the study groups could not be divided by baseline characteristics, such as time since amputation or length of time experiencing pain.