Endoscopic Topical Application (ETA) Therapy for Refractory Overactive Bladder: A First-in-Human Report

Refractory overactive bladder (OAB) remains a clinical challenge despite established therapies, such as anticholinergics, β3-agonists, and intradetrusor botulinum toxin (BTX). Emerging evidence suggests that sensory mechanisms within the bladder, including those involving the trigone where superficial afferent networks are present, may contribute to persistent urinary urgency and frequency in some patients. Although intradetrusor BTX injection is effective in selected patients, its impact on these superficial pathways may be limited because the injected drug predominantly distributes within the detrusor. Endoscopic topical application (ETA) therapy delivers BTX directly to the trigone under air cystoscopy, potentially providing targeted modulation of sensory hyperexcitability. We report a 72-year-old woman with long-standing refractory OAB who experienced only partial improvement with repeated intradetrusor BTX injections but achieved clinically meaningful symptom relief after ETA therapy. Nocturia, urgency, urgency urinary incontinence, and voided volume were improved, with no complications other than transient postoperative urethral pain. This case suggests that ETA therapy may represent a promising sensory-focused option for refractory OAB.