Belching is a type of physiological mechanism for venting gaseous material from the stomach to the pharynx with an audible sound.¹ Belching correlates with supragastric or gastric belching.^1-5 However, recent studies have described patients who cannot belch due to failure of the upper esophageal sphincter (UES) to relax.^6-8 These patients complained of recurrent chest pain, abdominal bloating, discomfort, or nausea.^6,7 They also complained of socially awkward chest or lower back gurgling noises.^6,7 The first descriptions were based on a few case reports from 1987.^9,10 In 2019, studies named this disease entity retrograde cricopharyngeus dysfunction (R-CPD), and botulinum toxin (BT) injection to the cricopharyngeus muscle was suggested as a treatment of choice.^7,11-13 High-resolution impedance manometry (HRIM) in patients with R-CPD showed nonspecific finding.^6,12 However, provocative testing with carbonated water drinking during HRIM showed failure of the UES to relax.^6,12 BT injection to UES reduced the basal pressure and restored belching ability.^12,13

In the study based on 50 patients with R-CPD by Arnaert et al,¹⁴ nearly 90% of patients showed improvement in symptoms regarding after 1 month of BT injection without major adverse events. Moreover, approximately 80% showed sustained symptomatic improvement at a median follow-up of 29 months. However, there is still lack of study of sham or control group in the treatment of BT in patients with R-CPD.¹² Moreover, R-CPD is still unfamiliar to the healthcare provider, and can affect patients’ quality of life.¹⁵ Therefore, understanding this disease is important.¹⁵ Further studies with well-designed protocols, including shame controls, are needed.

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