Prospective controlled study of endoscopic botulinum toxin injection for retrograde cricopharyngeus dysfunction, the inability to belch syndrome

Background: Complete inability to belch due to retrograde cricopharyngeus dysfunction (R-CPD) may lead to chronic gas-related gastrointestinal complaints. We aimed to validate high-resolution manometric (HRM) diagnostic criteria, and prospectively evaluate the feasibility and efficacy of cricopharyngeal botulinum toxin injection (CBTI) via flexible endoscopy. Methods: Consecutive manometrically diagnosed R-CPD patients were included. Asymptomatic volunteers were also included for diagnostic validation. R-CPD patients underwent CBTI (treatment group) or deferred/declined treatment (control group). Outcomes included ability to belch, clinical symptoms and quality of life measured using self-report questionnaires. Results: Sixty-five subjects were included (52 treatment group, 7 controls, 6 asymptomatic volunteers). All R-CPD patients had inability to belch since childhood. During HRM with carbonated drink provocative testing, all R-CPD patients demonstrated characteristic esophageal pressurization patterns associated with failure of upper esophageal sphincter relaxation; these findings were never seen in asymptomatic volunteers. At 3-months, 92% patients who received CBTI were able to belch (compared to 0 controls; P<0.001), and experienced improved clinical symptoms (global symptom score improved from 7.3 ± 1.7 to 1.8 ± 2.3, whereas in controls was static 7.5 ± 2.1 to 7.7 ± 1.8; P<0.0001 for comparison). Quality of life significantly improved in the treatment group but not controls (P=0.0002). At 3-months, 43/51 (84%) of the treatment group reported being ‘satisfied’ or ‘very satisfied’ with therapeutic outcome. Conclusion: HRM with carbonated drink provocation demonstrates pathognomonic signs of R-CPD that were not seen in health. Flexible endoscopic cricopharyngeal botulinum toxin injection is highly effective for symptomatic relief compared to no treatment.