<unk>  is a poorly understood disorder, and a number of theories have speculated the mechanisms that cause the regurgitation, which is a unique symptom to this disorder. While no theory has gained a consensus, some are more notable and widely published than others. The most widely documented mechanism is that the ingestion of food causes gastric distention, which is followed by abdominal compression and the simultaneous relaxation of the lower esophageal sphincter (LES). This creates a common cavity between the stomach and the oropharynx that allows the partially digested material to return to the mouth. There are several offered explanations for the sudden relaxation of the LES. Among these explanations is that it is a learned voluntary relaxation, which is common in those with or having had bulimia. While this relaxation may be voluntary, the overall process of<unk>  is still generally involuntary. Relaxation due to intra-abdominal pressure is another proposed explanation, which would make abdominal compression the primary mechanism. The third is an adaptation of the belch reflex, which is the most commonly described mechanism. The swallowing of air immediately prior to regurgitation causes the activation of the belching reflex that triggers the relaxation of the LES. Patients often describe a feeling similar to the onset of a belch preceding<unk> .
Rumination syndrome
Heat stroke
Precordial catch syndrome
Sympathicolysis
Shark attack
Overlap syndrome
Wooden chest syndrome
Raine syndrome