Altered Primary Motor Cortex Structure, Organization, and Function in Chronic Pain: A Systematic Review and...

Area of Science:

• Neuroscience
• Pain Research
• Motor Control

Background:

• Chronic pain is frequently linked to motor abnormalities.
• The primary motor cortex (M1) is crucial for movement planning and execution.
• Previous studies suggest M1 alterations in individuals with chronic pain.

Purpose of the Study:

• To systematically review and evaluate evidence of altered M1 structure, organization, and function in chronic pain.
• To assess changes in both neuropathic and non-neuropathic pain conditions.

Main Methods:

• Systematic literature search across multiple databases.
• Methodological quality assessment using a modified STrengthening the Reporting of OBservational studies in Epidemiology checklist.
• Meta-analyses, including subgroup analyses by pain condition, were performed where feasible.

Main Results:

• Sixty-seven studies involving 2,290 participants were included, utilizing diverse neurophysiological measures.
• Meta-analyses indicated increased M1 long-interval intracortical inhibition in chronic pain populations.
• Evidence for altered M1 structure, organization, and function remains conflicting and inconclusive for most measures.

Conclusions:

• The current evidence for M1 structural, organizational, and functional changes in chronic pain is inconsistent.
• Further research with larger sample sizes and rigorous methodologies is necessary to clarify M1 alterations in chronic pain.