Randomized Controlled Trial of the Effects of Repetitive Transcranial Magnetic Stimulation and Mirror Therapy on Phantom Limb Pain in Amputees

  Objective  To investigate the effect of repetitive transcranial magnetic stimulation (rTMS) on phantom limb pain (PLP) in amputees, and to compare the therapeutic effect with that of mirror therapy (MT).

  Methods  The study was designed as a randomized controlled trial. The evaluators were blinded, while the subjects and the therapists were unblinded. Subjects were randomly assigned to either the rTMS group or the MT group with a computer-generated random number table. From June 2018 to December 2020, from out of 45 amputee patients screened for the study, 30 who met the inclusion criteria were recruited for the study. All patients were recruited from the Rehabilitation Medicine Center, West China Hospital, Sichuan University. In the end, 4 patients withdrew from the study and 26 patients (12 in the rTMS group and 14 in the MT group) completed the prescribed treatment and evaluation. The rTMS group was given rTMS (1 Hz, 15 min, 5 d/week) for 2 weeks in addition to conventional rehabilitation therapy, while the MT group received MT (corresponding movements of limbs, 15 min, 5 d/week) for 2 weeks in addition to conventional rehabilitation therapy. PLP was evaluated by the Visual Analogue Scale (VAS) and Douleur Neuropathique 4 Questions (DN-4). Subjects were assessed before treatment (t₀), immediately after the completion of the treatment (t₁) and 3 months after the completion of the treatment (t₂).

  Results  The mean age of the 26 patients was 39.73±12.64. There were 15 males and 11 females. According to the reported description of the characteristics of the PLP by the patients, the characteristics with the highest incidence were tingling, stabbing, numbing, electric shocks and burning in descending order. There was no significant difference in the incidence of PLP characteristics between the two groups (P>0.05). The two groups had comparable baseline data, showing no significant difference in VAS and DN-4 between the two groups at t₀ (P>0.05). At t₁ and t₂, the VAS and DN-4 scores were decreased from those of t₀, showing statistically significant difference in both groups (P<0.01 for both scores). In the rTMS group, there was no significant difference between VAS and DN-4 scores at t₁ and those at t₂ (P>0.05). In the MT group, the VAS and DN-4 scores at t₂ were significantly lower than those of t₁ (P<0.05). There was no statistically significant difference between the rTMS group and MT group in the changes in pain measurements, i.e., VAS and DN-4 scores, before and after the intervention (P>0.05). The 26 patients who completed the experiment showed no dizziness, headache, or other abnormalities during the study.

  Conclusion  The results of this study indicate that repetitive transcranial magnetic stimulation could improve PLP in amputees, and the improvement effect was comparable to that of mirror therapy.