IEM is associated with an increased acid clearance times in the distal oesophagus. Gastropharyngeal reflux causes supraoesophageal manifestations such as globus, chronic cough, hoarseness, asthma, chronic sinusitis, or other otorhinolaryngologic diseases. It might be hypothesised that patients with IEM would be unable to clear refluxed acid; this would lead to a prolonged oesophageal dwell time of the refluxed acid and then the refluxed acid would reach to a higher level. As a result, it would be presumed that patients with IEM have more gastropharyngeal reflux than those patients with normal oesophageal motility.
A research article published on 21 October 2008 in the World Journal of Gastroenterology addresses this question. The research team led by Prof. Kim from Pusan National University Hospital evaluated the association between IEM and gastropharyngeal reflux in a large series of patients who underwent ambulatory 24-hour dual-probe pH monitoring for the evaluation of supraoesophageal symptoms. They showed that the frequency of gastrooesophageal reflux disease (GERD) and gastropahryngeal reflux disease, as defined by ambulatory pH monitoring was not different between the patients with normal oesophageal motility and those with IEM.
Why is IEM not associated with GPRD as well as GERD? Conventional manometry may be unable to evaluate the 'true effectiveness' of oesophageal peristalsis. In addition, the refluxed acid is neutralised by both the oesophageal submucosal secretions and the swallowed salivary secretions, so it becomes non-acid reflux material. Therefore, even though this non-acid refluxate in the upper level actually increased in the patients with IEM, the proximal pH probe cannot detect it. To solve this problem, a prospective study using a combined multichannel intraluminal impedance and pH measurement, which are able to detect both acid and non-acid reflux, as well as the proximal extent of the refluxate, will be needed.