Transcranial Magnetic Stimulation Measures of Corticospinal Excitability in Black and Hispanic/Latino People with Painful Peripheral Neuropathy

This study aims to provide preliminary descriptive data on transcranial magnetic stimulation (TMS) measures obtained in Black and Hispanic/Latino individuals with chronic painful peripheral neuropathy (PN), including those with chemotherapy-induced peripheral neuropathy (CIPN) and diabetic neuropathy (DN). CIPN and DN share similar neuropathic symptoms and underlying physiological mechanisms, in particular altered central nervous system processing. TMS is a non-invasive technique that can assess corticospinal excitability and the function of GABAergic and glutamatergic pathways, potentially serving as a diagnostic tool for PN. This secondary analysis utilized data from a pilot randomized sham-controlled trial of transcutaneous auricular vagus nerve stimulation (taVNS) in people with PN. TMS measures, including resting motor threshold (RMT), unconditioned MEP amplitude (spTMS), short interval intracortical inhibition (SICI), and intracortical facilitation (ICF), were assessed at baseline over 2 separate visits. Test-retest reliability was evaluated, and changes in TMS measures following transcutaneous auricular vagus nerve stimulation were analyzed. Baseline TMS measures showed no significant differences between CIPN and DN groups. The study found good test-retest reliability for TMS measures, with ICC values between 0.73 and 0.87 for all TMS measures. Post taVNS, neuropathic pain symptoms improved, with a slight decrease in ICF. Overall, TMS measures demonstrated good reliability in this sample of Black and Hispanic/Latino individuals with PN, and these findings provide valuable preliminary data for future studies aimed at establishing the psychometric properties and diagnostic utility of TMS measures in PN.