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). Both 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 or prognostic tool for PN.

Methods

This study utilized data from a pilot randomized sham-controlled trial that tested the impact of patient education videos on the effect of transcutaneous auricular vagus nerve stimulation (taVNS) in Black and Hispanic/Latino individuals living with PN. TMS measures, including resting motor threshold (RMT), MEP amplitude following unconditioned single-pulse TMS (spTMS) and paired-pulse TMS measures of short interval intracortical inhibition (SICI), and intracortical facilitation (ICF), were assessed twice on separate visits. Test-retest reliability was evaluated, and changes in TMS measures following transcutaneous auricular vagus nerve stimulation were computed.

Results

Pre-intervention TMS measures showed smaller-than-medium sized differences between CIPN and DN groups. The study found good test-retest reliability for TMS measures, with ICC values between 0.69 and 0.95 for all TMS measures of interest.

Discussion

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.