"Gas" laryngopharyngeal reflux cause unexplained chronic cough.

Hypopharyngeal multichannel intraluminal impedance (HMII) that can measure laryngopharyngeal reflux (LPR) events has supported the causal relationship between chronic cough (CC) and LPR containing liquid. However the role of "gas" LPR associated with CC has been poorly understood. We present two cases of patients with CC who had negative LPR containing liquid but had multiple episodes of "gas" LPR on HMII. The majority of "gas" LPR events had a minor pH drop at hypopharynx. Since any etiology of CC was excluded and medical therapy failed, both patients underwent laparoscopic antireflux surgery (LARS). Both of the patients had complete resolution of cough postoperatively. The present cases demonstrated successful outcome of LARS to treat the patients with CC who had documented "gas" LPR on HMII, thus suggesting the causal relationship between CC and "gas" LPR. The number of "gas" LPR events may need to be considered as an important diagnostic parameter.