Prospective Controlled Study of Endoscopic Botulinum Toxin Injection for Retrograde Cricopharyngeus Dysfunction: The Inability to Belch Syndrome.

[INTRODUCTION] 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) by flexible endoscopy.

[METHODS] Consecutive manometrically diagnosed patients with R-CPD were included. Asymptomatic volunteers were also included for diagnostic validation. Patients with R-CPD 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, and 6 asymptomatic volunteers). All patients with R-CPD 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 with 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.

[DISCUSSION] HRM with carbonated drink provocation demonstrates pathognomonic signs of R-CPD that were not seen in health. Flexible endoscopic CBTI is highly effective for symptomatic relief compared with no treatment.