The immediate effect of acupuncture on brain function in patients with chronic itch: a study protocol for an fNIRS investigation.

Background: Chronic itch significantly affects patients' quality of life. Acupuncture shows therapeutic potential for chronic itch, while its neural mechanisms remain unclear. This study aims to investigate the immediate anti-itch effects of acupuncture in patients with chronic itch and explores the underlying neural mechanisms through functional near-infrared spectroscopy (fNIRS) monitoring. Methods: This study is a randomized controlled design. A total of 40 participants with chronic itch will be randomly assigned to the verum acupuncture group or the sham acupuncture group. The fNIRS will be used to monitor hemodynamic activity and functional connectivity of the prefrontal cortex and motor areas. The data will be continuously acquired across three consecutive 5-min epochs: (1) pre-stimulation baseline (5 min before needle insertion), (2) intra-stimulation phase (during 5-min needle retention), and (3) post-stimulation observation (5 min immediately after needle withdrawal). The primary outcome is the change in itch numeric rating scale score, secondary outcomes include the degree of itch relief, immediate comfort, intensity of itch, deqi intensity scale and expectation of therapeutic effect. In addition, both regional brain activation and functional connectivity will be analyzed. Discussion: This study plans to observe the immediate anti-itch effects of acupuncture for patients with chronic itch and reveal associated brain functional changes using fNIRS. The findings will provide a neurobiological basis for the anti-pruritic mechanisms of acupuncture. Clinical trial registration: http://itmctr.ccebtcm.org.cn/, identifier ITMCTR2025001506.