| Background and Aim: Esophageal motility disorder (EMD) is a major cause of non-cardiac chest pain and dysphasia. Based on the Chicago classification ver3.0, the first step when making a diagnosis is to evaluate the function of EGJ relaxation, and the assessment of the integrated relaxation pressure (IRP) is the gold standard for determining whether the EGJ relaxation is impaired. We sometimes encounter cases in which a diagnosis is difficult because the IRP is close to the upper limit of normal. Therefore, another approach for evaluating EGJ relaxation besides IRP is awaited. To achieve this, we must first determine how successful EGJ relaxation is achieved, which was the objective of the present study. Method: Sixteen participants with normal HRM results were enrolled. The participants were asked to perform a dry swallow 5 times and then a wet swallow when drinking 5 ml of water 5 times. Result: There are two mechanisms that cause EGJ relaxation: EGJ receptive relaxation (EGJRR) and swallow-induced EGJ relaxation (SEGJR). The extent of EGJ relaxation (11.2±1.6 mmHg, n=16) in dry swallowing was smaller than that (19.1±2.7 mmHg, n=16) found in wet swallowing, since EGJRR was not observed in dry swallowing (-0.6±1.4 mmHg, n=16) but was seen in wet swallowing. Furthermore, the extent of SEGJR with wet swallowing (14.4±1.8 mmHg, n=16) was significantly larger than that with dry swallowing (11.8±1.5 mmHg, n=16). Conclusion: Both EGJRR and SEGJR are indispensable for successful EGJ relaxation during food intake. Assessing these two major mechanisms in greater detail may be a promising approach to the evaluation of EGJ relaxation other than IRP. |
