TMS-Indexed neurophysiological signatures of neural compensation in spinal cord injury: associations with injury level, motor function, and affective modulation.

BACKGROUND

Spinal cord injury (SCI) impairs motor, autonomic, and sensory functions from nerve damage. Transcranial Magnetic Stimulation (TMS) enables non-invasive assessment of cortical excitability, essential for understanding neuroplasticity and its role in motor and cognitive recovery in SCI patients.

OBJECTIVE

To identify associations between sociodemographic and clinical factors predicting corticospinal excitability in SCI patients.

METHODS

We analyzed 102 individuals from the DEFINE cohort using cross-sectional analysis and linear and logistic regression models. TMS metrics were primary outcomes.

RESULTS

Age correlated positively with Motor Threshold (MT) (β = 0.29, p < 0.001), and non-white participants had higher MT than white participants (β = 4.79, p = 0.028). Thoracic and lumbar lesions were negatively associated with MT (β = -9.34, p < 0.001; β = -13.13, p < 0.001). Thoracic and lumbar lesions increased the odds of Motor Evoked Potentials (MEP) above the median by 62.2% (OR = 1.62, p < 0.001) and 54% (OR = 1.54, p = 0.011), respectively. Higher hand strength was linked to lower Intracortical Inhibition (ICI) (β = -0.0062, p = 0.023), while anxiety increased ICI (β = 0.0311, p = 0.003). Females had higher Intracortical Facilitation (ICF) than males (β = 0.14, p = 0.033), and lumbar lesions increased ICF compared to cervical (β = 0.147, p = 0.026).

CONCLUSION

Cortical excitability in subjects with SCI is influenced by age, race, lesion level, and psychological factors. The observed associations in motor threshold, theta activity, and lesion level underscore the need for personalized rehabilitation strategies.