Pain-Induced Reduction in Corticomotor Excitability is Counteracted by Combined Action-Observation and Motor Imagery

Musculoskeletal pain reduces corticomotor excitability (CE) and methods modulating such CE reduction remain elusive. This study aimed to modulate pain-induced CE reduction by performing action observation and motor imagery (AOMI) during experimental muscle pain. Twelve healthy participants participated in 3 cross-over and randomized sessions separated by 1 week. During the AOMI session subjects performed an AOMI task for 10 minutes. In the AOMI+PAIN session, hypertonic saline was injected in the first dorsal interosseous muscle before performing the AOMI task. In the PAIN session, participants remained at rest for 10 minutes or until pain-resolve after the hypertonic saline injection. CE was assessed using transcranial magnetic stimulation motor-evoked potentials (TMS-MEPs) of the first dorsal interosseous muscle at baseline, during, immediately after, and 10 minutes after AOMI and/or PAIN. Facilitated TMS-MEPs were found after 2 and 4 minutes of AOMI performance (P < .017) whereas a reduction in TMS-MEPs occurred at 4 minutes (P < .017) during the PAIN session. Performing the AOMI task during pain counteracted the reduction in CE, as evident by no change in TMS-MEPs during the AOMI+PAIN session (P > .017). Pain intensity was similar between the AOMI+PAIN and PAIN sessions (P = .71). This study, which may be considered a pilot, demonstrated the counteracting effects of AOMI on pain-induced decreases in CE and warrants further studies in a larger population. Perspective: This is the first study to demonstrate a method counteracting the reduction in CE associated with acute pain and advances therapeutic possibilities for individuals with chronic musculoskeletal pain.