tDCS for Reducing the Incidence of OEI After Cesarean Section

Cesarean section is the most common obstetric surgery worldwide. Epidural anesthesia hasbecome the preferred anesthesia method for cesarean sections due to its definiteanalgesic effect and minimal impact on mother and baby. To ensure postoperativeanalgesia, intrathecal administration of morphine (the preferred opioid for obstetricintrathecal analgesia) is a routine clinical protocol, but morphine‐induced postoperativepruritus is a common adverse reaction. A study targeting the cesarean section populationconfirmed that the incidence of pruritus after epidural morphine administration is ashigh as 40%‐75%.Transcranial direct current stimulation (tDCS) can enhance the activityof GABAergic inhibitory interneurons in the spinal dorsal horn through thecortical‐spinal descending pathway, reverse the inhibitory effect of morphine on them,and restore negative feedback regulation of itch‐specific GRPR⁺ neurons; at the sametime, it downregulates the phosphorylation level and membrane expression of μ‐opioidreceptors in the spinal dorsal horn, weakening the receptor activation efficiency ofmorphine. On the other hand, tDCS can reduce peripheral nerve excitability, decrease mastcell degranulation in the skin, and reduce the release of histamine and tryptase;simultaneously, it inhibits the activation of glial cells in the spinal cord/cortex,decreases the secretion of pro‐inflammatory factors such as TNF‐α and IL‐6, and blocksthe vicious cycle of 'inflammation‐receptor upregulation‐itch exacerbation,' therebyreducing the occurrence of itch.This study aims to explore the effect of transcranialdirect current stimulation (tDCS) on the incidence of morphine‐induced itching aftercesarean section by inhibiting the central itch perception circuits in cesarean sectionpatients and antagonizing the disinhibitory effects mediated by μ‐opioid receptors in thespinal dorsal horn.