Pharyngeal electrical stimulation favorably modifies healthy human pharyngoesophageal function: a randomized trial using high-resolution manometry impedance.

Abstract

Despite positive clinical evidence for the effects of pharyngeal electrical stimulation (PES) on swallowing performance in disease, it remains unknown which specific swallow characteristics improve. Using high-resolution manometry impedance (HRMI) with pressure flow analysis (PFA), we aimed to assess the effects of PES on normal swallow function and to evaluate the impact of pharyngeal length variability on electrode placement. As part of a prospective randomized controlled trial (RCT), 20 asymptomatic volunteers were randomly assigned to 3 days of PES or SHAM treatment. HRMI assessments were conducted at baseline (during which pharyngeal length measurements were acquired) and repeated at 1-2 h, and at 24-72 h following PES or SHAM treatment. Twenty healthy adults [10 males, median age: 28.0 (interquartile range, IQR 23.8-45.0) yr, age range: 20-65 yr] participated in this RCT. We developed an objective, standardized method of catheter placement based on pharyngeal length measurements. Over 3 days, the median stimulation intensity of PES was 11 mA. When compared with the SHAM group, the PES group scored better on multiple pharyngeal and esophageal metrics resulting in improved global swallow function values 1-2 h after treatment (P = 0.029). One day later, most of these beneficial effects were no longer present. This study suggests that PES can temporarily alter swallow function in healthy individuals. Functional reserve in healthy individuals may be further enhanced by PES. In the majority of volunteers, electrode position needed to be adjusted 1-3 cm to account for variations in pharyngeal length.NEW & NOTEWORTHY Pharyngeal electrical stimulation (PES) positively influences clinical swallow-outcomes in patients with neurogenic dysphagia. Its effect on the underlying swallowing physiology remains unknown. Our study evaluated this effect of PES in healthy individuals using high-resolution manometry impedance. PES showed short-term improved pharyngeal contractility, upper esophageal sphincter relaxation, proximal esophageal contractility and bolus flow, resulting in improved swallowing. One day later, most of these beneficial effects were no longer present as expected in already intact swallow systems.