The Influence of Experimental Pain on Primary Motor Cortex Function: Protocol for a Systematic Review and Meta-analysis

Abstract

Introduction: The primary motor cortex (M1) is a key brain region implicated in pain processing. Here, we present a protocol for a review that aims to synthesise and critically appraise the evidence for the effect of experimentalpain on M1 function. Methods/Analysis: A systematic review and meta-analysis will be conducted. Electronic databases will be searched using a predetermined strategy. Studies published before April 2020 that investigate the effects of experimentally induced pain on corticomotor excitability (CME) in healthy individuals will be included if they meet eligibility criteria. Study identification, data extraction andrisk of bias assessment will be conducted by two independent reviewers, with a third reviewer consulted for any disagreements. The primary outcomes will include group level changes in CME and intracortical, transcortical and sensorimotor modulators of CME. A separate analysis using individual data will also be conducted to explore individual differences in CME in response to experimental pain. The meta-analysis will consider the following factors: pain model (transient, tonic, transitional pain), type of painful tissue (cutaneous, musculoskeletal), time points of outcome measures(during or after recovery from pain) and localisation of pain(target area, control area). Discussion: This review will provide a comprehensive understanding of the mechanisms within M1 that mediate experimentally induced pain, both on a group and individual level. Registration Number: The systematic review is registered with the International Prospective Register of Systematic Reviews (#CRD42020173172)