Selective Stimulation of C fibers for Chronic Pain Relief

The chronic pain reduces people's quality of life (QOL). It is a social problem growing in countries that are ageing. Opioid drugs are expected as a long-lasting pain inhibitor or relief for chronic pain. However, due to the addiction and strict national control, using opioids could not accepted by most patients as a general treatment stimulating unmyelinated nerve fibers: C fibers near the sarcolemma using needle electrodes, or acupuncture could induce the secretion of endogenous opioid. However, due to the invasiveness of needle treatment and the expert skill needed, it is difficult to apply to family individuals. Endogenous-opioid-based pain relief by selective stimulation through surface electrodes is a strong candidate to push the pain relief technology into a home environment. In this study, we simulated the C and Aδ fibers using the Hodgkin-Huxley (HH) model and the MRG model, respectively. Bipolar Square Waves (BSW) and Bipolar high frequency modulated wave (BMP) of different frequencies were tested. The effects of frequency bands, ISI (inter-stimulation interval) and polarity asymmetry on the selectivity of C fiber were investigated. This study contributes to the understanding of the selective stimulation of C and Aδ fibers. The stimulation with the frequency lower than 100 Hz and asymmetric waveform may have potential clinical application of pain suppression.