Phantom limb pain relief by contralateral myofascial injection with local anaesthetic in a placebo-controlled study: Preliminary results

OBJECTIVE: To ascertain the existence of contralateral painful muscle areas mirroring phantom pain and to evaluate the short-term effects of anaesthetic vs saline, injected contra notlaterally to control phantom and phantom limb pain. DESIGN: Double-blinded cross-over study. SETTING: Inpatients; rehabilitation institute. PARTICIPANTS: Eight lower limb amputees with phantom limb pain in the past 6 months. INTERVENTIONS: Either 1 ml of 0.25% bupivacaine or 0.9% saline injected alternately in each point with a 28-gauge needle, with 72 h between injections. Main outcome measurePhantom sensation modification and the intensity of phantom limb pain (visual analogue scale) before and after injections. RESULTS: Although present, painful muscle areas in the healthy limb do not mirror the topographical distribution of phantom limb pain. Sixty minutes after the injection, a statistically significant greater relief of phantom limb pain was observed after using local anaesthetic than when using saline injection (p = 0.003). Bupivacaine consistently reduced/abolished the phantom sensation in 6 out of 8 patients. These effects on phantom sensation were not observed after saline injections. CONCLUSION: Contralateral injections of 1 ml 0.25% bupivacaine in myofascial hyperalgesic areas attenuated phantom limb pain and affected phantom limb sensation. The clinical importance of this treatment method requires further investigation.