The Relationship Between Corticomotor Reorganization and Acute Pain Severity: A Randomized, Controlled Study Using Rapid Transcranial Magnetic Stimulation Mapping

Rocco Cavaleri, Lucy S. Chipchase, Simon J. Summers, Jane Chalmers, Siobhan M. Schabrun

Research output: Contribution to journalArticlepeer-review

Abstract

OBJECTIVE: Although acute pain has been shown to reduce corticomotor excitability, it remains unknown whether this response resolves over time or is related to symptom severity. Furthermore, acute pain research has relied upon data acquired from the cranial "hotspot," which do not provide valuable information regarding reorganization, such as changes to the distribution of a painful muscle's representation within M1. Using a novel, rapid transcranial magnetic stimulation (TMS) mapping method, this study aimed to 1) explore the temporal profile and variability of corticomotor reorganization in response to acute pain and 2) determine whether individual patterns of corticomotor reorganization are associated with differences in pain, sensitivity, and somatosensory organization. METHODS: Corticomotor (TMS maps), pain processing (pain intensity, pressure pain thresholds), and somatosensory (two-point discrimination, two-point estimation) outcomes were taken at baseline, immediately after injection (hypertonic [n = 20] or isotonic saline [n = 20]), and at pain resolution. Follow-up measures were recorded every 15 minutes until 90 minutes after injection. RESULTS: Corticomotor reorganization persisted at least 90 minutes after pain resolution. Corticomotor depression was associated with lower pain intensity than was corticomotor facilitation (r = 0.47 [P = 0.04]). These effects were not related to somatosensory reorganization or peripheral sensitization mechanisms. CONCLUSIONS: Individual patterns of corticomotor reorganization during acute pain appear to be related to symptom severity, with early corticomotor depression possibly reflecting a protective response. These findings hold important implications for the management and potential prevention of pain chronicity. However, further research is required to determine whether these adaptations relate to long-term outcomes in clinical populations.

Original languageEnglish
Pages (from-to)1312-1323
Number of pages12
JournalPain Medicine
Volume22
Issue number6
DOIs
Publication statusPublished - Jun 2021

Keywords

  • Corticomotor Reorganization
  • Pain
  • Sensitivity
  • Transcranial Magnetic Stimulation

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