Acidic Pharyngeal Reflux Does Not Correlate with Symptoms and Laryngeal Injury Attributed to Laryngopharyngeal Reflux

Abstract

Background: Laryngopharyngeal reflux (LPR) is suspected when the symptoms are attributed to the penetration of acidic gastroesophageal reflux (GER) into the larynx. However, the relationships between the intensity of LPR and symptoms and laryngeal injury have not been elucidated. Several factors confound the study of LPR, namely pH is monitored in the pharynx (pharyngeal reflux) but the pharyngeal acidity (pH) required to induce laryngeal injury is unknown, the GER origin of pharyngeal acid is not always established, and a recent treatment with proton pump inhibitors (PPI) confounds the analysis.

Aims: We aimed to limit these confounding factors to analyze the relationship between LPR and symptoms and laryngeal injury.

Methods: We used dual pharyngeal and distal esophageal 24-h pH/impedance monitoring to establish GER origin of pharyngeal reflux, we used an unbiased approach to analysis by evaluating a whole range of acidity (pH < 6, pH < 5.5, pH < 5.0, pH < 4.5 and pH < 4.0) in patients with suspected LPR without PPI for > 30 days.

Results: Pharyngeal reflux was (median[IQR]) 14[8-20.5] and 4[1.5-6.5] pharyngeal reflux episodes with pH < 6.0 and pH < 5.5, respectively. Pharyngeal reflux with pH < 5.0 was rare. Comprehensive analysis did not reveal any correlation between symptoms (reflux symptom index) or laryngeal injury (reflux finding score) and the number of pharyngeal reflux episodes or duration of pharyngeal acid exposure at any pH level.

Conclusion: Unbiased comprehensive approach did not reveal any relationship between acidic pharyngeal reflux and the symptoms or laryngeal injury attributed to LPR. Limited clinical usefulness of pharyngeal monitoring reported by others is unlikely due to confounding factors.

Keywords: Acid; Gastroesophageal reflux; Laryngopharyngeal reflux; Reflux finding score; pH–impedance monitoring.

Fig. 1

Recording of pharyngeal reflux. a Representative example of a dual pH sensor catheter placing. The pH sensors were located 1 cm above the UES and 5 cm above the LES. Impedance electrodes are located 1 cm above and 2, 5, and 7 cm below the proximal pH sensor and 1 cm above and 1 and 3 cm below the distal pH sensor. b Representative trace of pharyngeal acidic reflux episode recorded by dual pharyngeal and distal esophageal pH/impedance. Sudden drop of pH and impedance in the distal esophagus (black arrow, GER) is followed by distal to proximal decrease in impedance (distal to proximal movement of the refluxate) and subsequent drop of pH in the pharyngeal pH sensor (red arrow, LPR)

Fig. 2

Quantification of pharyngeal acidic reflux in patients diagnosed with LPR. a Number of pharyngeal acidic reflux episodes with indicated acidity during 24 h. b Duration of pharyngeal acid exposure calculated as cumulative time pH of pharyngeal reflux was below indicated pH during 24 h. N = 27

Fig. 3

Pharyngeal acidic reflux correlates with distal esophageal acidic reflux in patients diagnosed with LPR. **P < 0.01. a Correlation between the number of pharyngeal acidic (pH < 6.0) reflux episodes and distal esophageal acidic (pH < 4.0) reflux episodes. b Correlation between the duration of pharyngeal acidic (pH < 6.0) exposure and distal esophageal acid (pH < 4.0) exposure time

Fig. 4

Pharyngeal acidic reflux does not correlate with reflux symptom index (RSI) or reflux finding score (RFS) in patients diagnosed with LPR. a, b The relationship between pharyngeal acidic (pH < 6.0) reflux and RSI in RSI-positive (RSI > 13) patients (N = 20, r > 0.37 is required for positive directional correlation for P < 0.05). c, d Relationship between pharyngeal acidic (pH < 6.0) reflux and RFS in RFS-positive patients (N = 21, r> 0.36 is required for positive directional correlation for P < 0.05)