This is a multicenter, randomized, double-blind, sham-controlled, 2x2 factorial trial investigating the efficacy of combining repetitive Transcranial Magnetic Stimulation (rTMS) with gut-directed therapy for chronic visceral pain in diarrhea-predominant irritable bowel syndrome (IBS-D).
Scientific rationale: Current treatments for IBS-D often provide inadequate relief. rTMS, a non-invasive neuromodulation technique, may alleviate pain by restoring cortical excitability and neural plasticity. Its potential synergy with gut-targeted agents (antispasmodic or probiotic) remains unexplored.
Objectives: The primary objective is to determine the interaction effect between rTMS (real vs. sham) and drug (pinaverium bromide vs. bifidobacterium) on the composite response rate at Week 2. Secondary objectives include assessing changes in IBS-SSS, IBS-QoL, PHQ-9 scores, and anorectal manometry parameters.
Methodology: 140 eligible adults will be randomized equally into four groups: (1) real rTMS + pinaverium bromide, (2) real rTMS + bifidobacterium, (3) sham rTMS + pinaverium bromide, (4) sham rTMS + bifidobacterium. Real rTMS will be delivered at 1Hz, 80% MT over the mPFC for 20 minutes daily for 2 weeks. Sham rTMS uses a placebo coil. Pinaverium bromide (50mg tid) and bifidobacterium (500mg bid) will be administered with matched placebos to maintain blinding. Participants, outcome assessors, and statisticians will be blinded to intervention assignments.
Outcomes: The primary outcome is the proportion of participants achieving composite response (≥30% reduction in worst abdominal pain AND ≥50% reduction in days with BSFS 6/7 stools) at Week 2. Secondary outcomes include changes from baseline in IBS-SSS, IBS-QoL, PHQ-9, and manometry measures.
Statistics: A factorial ANOVA will be used to test the main and interaction effects. The primary analysis will follow the intention-to-treat principle.