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.
