Why so Many Patients With Dysphagia Have Normal Esophageal Function Testing

Abstract

Esophageal peristalsis involves a sequential process of initial inhibition (relaxation) and excitation (contraction), both occurring from the cranial to caudal direction. The bolus induces luminal distension during initial inhibition (receptive relaxation) that facilitates smooth propulsion by contraction travelling behind the bolus. Luminal distension during peristalsis in normal subjects exhibits unique characteristics that are influenced by bolus volume, bolus viscosity, and posture, suggesting a potential interaction between distension and contraction. Examining distension-contraction plots in dysphagia patients with normal bolus clearance, ie, high-amplitude esophageal peristaltic contractions, esophagogastric junction outflow obstruction, and functional dysphagia, reveal 2 important findings. Firstly, patients with type 3 achalasia and nonobstructive dysphagia show luminal occlusion distal to the bolus during peristalsis. Secondly, patients with high-amplitude esophageal peristaltic contractions, esophagogastric junction outflow obstruction, and functional dysphagia exhibit a narrow esophageal lumen through which the bolus travels during peristalsis. These findings indicate a relative dynamic obstruction to bolus flow and reduced distensibility of the esophageal wall in patients with several primary esophageal motility disorders. We speculate that the dysphagia sensation experienced by many patients may result from a normal or supernormal contraction wave pushing the bolus against resistance. Integrating representations of distension and contraction, along with objective assessments of flow timing and distensibility, complements the current classification of esophageal motility disorders that are based on the contraction characteristics only. A deeper understanding of the distensibility of the bolus-containing esophageal segment during peristalsis holds promise for the development of innovative medical and surgical therapies to effectively address dysphagia in a substantial number of patients.

Keywords: Distension Contration Plot; Dysphagia; Esophageal Peristalsis; Functional Dysphagia.

Figure 1

(A–C) Prevalence of esophageal motor disorders in patients with dysphagia referred for esophageal manometry from 3 tertiary care centers.

Figure 2

Bolus moves through the esophagus in the shape of an “American Football” during peristaltic transport during primary and secondary peristalsis, recorded by 3 different methods: 1) ultrasound image derived data, 2) Antegrade contraction recorded by Endoflip technique, and 3) impedance derived luminal cross-sectional area of the esophagus.

Figure 3

Effect of posture and bolus viscosity on the distension-contraction waveforms. Esophageal distension shown as waveform and contraction as color heat map. Saline bolus in the supine position arrives much faster in the mid and distal esophagus as compared to the Trendelenburg position (A and C). The latter position slows the speed of bolus and bolus travels closer to the contraction wave along the length of the esophagus. Viscous bolus moves slowly through the esophagus in close relationship with the onset of contraction. Supine (B) vs Trendelenburg (D) position with viscous bolus did not influence the temporal relationship between contraction and dissension waveform. Reproduced with permission from Mittal RK, Muta K, Ledgerwood-Lee M, et al. Relaionship between distension-contraction waveforms during esophageal peristalsis: effect of bolus volume, viscocity and posture:In Press. Am J Physiol 2020; 319(4):G454–G467.

Figure 4

m-Mode US image at 5 cm above the LES along with impedance line tracing to show the relationship between bolus arrival, bolus clearance, luminal distension, and muscle thickness with swallows in normal subject (A), and 3 patients with achalasia esophagus type 3 (B–D). X axis is time in these recordings. Yellow arrows show that unlike normal subject, there is luminal closure before arrival of bolus in achalasia 3 esophagus which results in delayed arrival of bolus in the distal esophagus and bolus travelling closer to the contraction wave. D shows luminal opening, followed by collapse (green arrow) and then opening again in this swallow. Time 1 = time between the onset of swallow and bolus arrival, Time 2 = time between bolus arrival and bolus clearance. Reproduced with permission from Park S, Zifan A, Kumar D, et al. Genesis of esophageal pressurization and bolus flow patterns in patients with achalasia esophagus. Gastroenterology 2018;155:327–336.

Figure 5

Distension-contraction plots in a normal subject (A), a patient with nutcracker esophagus (C), function dysphagia (B) and esophagogastric junction outflow obstruction (D). Distension is seen as waveform and contraction as a color topograph. Note that the bolus arrives in the distal esophagus much ahead of the contraction. Also note that the amplitude of distension is smaller in patients. Finally, note the difference in the distension waveform between normal and patients.

Figure 6

Distension-contraction plots in a normal subject (A), a patient with nutcracker esophagus (C), function dysphagia (B) and esophagogastric junction outflow obstruction (D). Serial images during one swallow in each subject. These 4 subjects are same as in Figure 5. Note the differences in the temporal relationship between distension and contraction in normal subject vs patients. Also the amplitude of distension is smaller in patients with dysphagia but different diagnosis based on the manometry study.

Figure 7

The schematic show relationship between contraction and distension in normal subject (top row), patient with functional dysphagia (middle row) and patient with achalasia 3 esophagus (bottom row) Top row: The esophagus distends in the shape of an “American Football” ahead of the contraction. Middle row: Note a narrow lumen esophagus distal to the contraction wave that results in rapid transit of bolus to the distal esophagus. Bottom row: Note, luminal occlusion distal the distension that impedes the bolus flow.