Motor Evoked Potentials in Preclinical Models of Spinal Cord Injury and Stroke in Rodents: A Systematic Review.
Motor Evoked Potentials (MEPs) serve as an invaluable tool for assessing corticospinal tract (CST) integrity and motor pathway function in preclinical models of spinal cord injury (SCI) and stroke. Despite their diagnostic and prognostic utility, substantial methodological variability persists across studies, complicating interpretation and cross-study comparisons. This systematic review synthesizes MEP acquisition and interpretation protocols from 83 rodent SCI and stroke studies published since 2015, aiming to outline common practices, identify sources of variability, and highlight methodological gaps. Our analysis reveals a predominance of SCI models and a focus on hindlimb MEPs, employing diverse stimulation protocols including transcranial electrical stimulation (TES), direct cortical stimulation (DCoS), and transcranial magnetic stimulation (TMS). Anesthetic approaches are notably heterogeneous, representing a potentially large source of variability in MEP acquisition. Amplitude and latency, often measured jointly, emerged as the most frequently reported MEP parameters. Critically, MEPs bridge cellular and molecular changes to observable behaviour by reflecting the integrated functionality of neural cell populations and their circuits. However, a lack of standardization in reporting, particularly for secondary electrophysiological features and stimulation intensity, hinders reproducibility. We emphasize the necessity for standardized protocols for stimulation, electrode positioning, and data analysis, particularly the use of comprehensive recruitment curves. Adopting these best practices will enhance the transparency, comparability, and translational potential of MEP methodology in advancing our understanding and treatment strategies for neurological disorders.