Tracing of gastric reflux into the middle ear in a mongolian gerbil model

The purpose of this study was to trace induced gastric reflux and to examine whether it reaches the middle ear in a Mongolian gerbil model.

Otitis media with effusion is the most frequent middle ear disease in childhood. Gastroesophageal reflux is suspected to be a possible factor in its pathogenesis.

Seventeen Mongolian gerbils were assigned to three groups: the control (phosphate-buffered saline application to the lower esophageal sphincter) and two experimental groups (Aquo-Trinitrosan [Merck, Darmstadt, Germany] application to the lower esophageal sphincter, low gastric pressure and Aquo-Trinitrosan application, higher gastric pressure). We injected Chinese ink into the stomach to trace the path of a potential gastroesophageal reflux in all three groups. The traces of ink were investigated by ear and larynx endoscopy and histology.

There were no signs of gastroesophageal reflux based on the data obtained from the control group. In animals with traceable laryngeal reflux, the ink was also shown to advance through the eustachian tube and reach the middle ear. In addition, we found that when reflux reaches the middle ear on one side, it also reaches the contralateral middle ear in most cases.

Gastroesophageal reflux induced by relaxation of the lower esophageal sphincter was shown to reach the middle ear in our Mongolian gerbil model. These results support recent hypotheses linking gastroesophageal reflux to the development of otitis media with effusion.