Retrograde cricopharyngeus dysfunction (R-CPD), also known as inability to belch syndrome-a narrative review

Retrograde cricopharyngeus dysfunction (R-CPD), also known as 'inability to belch syndrome', is an under-recognized disorder wherein the upper esophageal sphincter (UES) fails to open following gaseous reflux. First described in 1987, R-CPD was rediscovered in 2019 along with the first effective treatment, endoscopic botulinum toxin (Botox) injection into the cricopharyngeus (CP). Since then, there has been an explosion of literature on R-CPD. The objectives of this review were to discuss the physiology of belching and R-CPD along with the epidemiology, diagnostic criteria, and clinical experience in managing R-CPD.

Relevant publications with an abstract in English were identified using the PubMed, Scopus, and Cochrane databases (time frame: 1987-November 15, 2025).

Along with an inability to belch, R-CPD is associated with an array of symptoms including gurgling noises in the chest, bloating, flatulence, and chest pain that can compromise a patient's quality of life. The ultimate cause of R-CPD is dysfunction of the vago-vagal reflex mediating UES opening in response to gaseous distention of the esophagus. This can be demonstrated with high-resolution manometry (HRM) by provoking the need to belch with ingestion of a carbonated beverage. However, most R-CPD cases come to light via internet forums such as "#noburpsyndrome" on TikTok and to date most cases (estimated in the thousands) have been treated without physiological confirmation. The reported success rate of Botox treatment is about 90% with only transient dysphagia as a side effect and with many treated patients having a response lasting beyond the expected 4-month duration of action of Botox. This suggests that many R-CPD cases may be amenable to behavioral/biofeedback therapy as has also been claimed on internet forums and in a published case report.

R-CPD is characterized by an inability to belch and a characteristic array of associated symptoms caused by physiological dysfunction of the UES. R-CPD is demonstrable by an HRM study with carbonated beverage provocation and treatable with Botox injection to the CP. Future studies are needed to clarify whether R-CPD exists in a mild-to-severe spectrum and what proportion of R-CPD cases are amenable to behavioral therapy.