Coexistence of oropharyngeal dysphagia and esophageal dysphagia have been reported in many cases [1]. Although the patient’s subjective complaint is the first important clue in differentiating between oropharyngeal dysphagia and esophageal dysphagia [2,3], many patients with esophageal dysphagia initially complained of pharyngeal symptoms [4,5]. In patients suspected of both esophageal and pharyngeal dysphagia, pharyngeal swallowing test is recommended first, primarily to differentiate the intra-airway aspiration [2]. Videofluoroscopic swallowing studies (VFSS) are one of the standard tests to evaluate pharyngeal swallowing function. We previously reported 7.5% of the patients undergoing the test showed some degree of esophageal dysphagia [6]. When barium in the esophagus with a diameter of 2 cm or more was observed after the VFSS test, lung cancer and esophageal cancer were confirmed through esophagogastroduodenoscopy (EGD) or chest computed tomography (CT) scan, and achalasia was confirmed through barium esophagogram [6].

Esophageal motility disorders are classified into major and minor motility disorders according to the Chicago Classification, based on findings of high-resolution esophageal manometry (HREM) [7]. No previous attempt has been made to classify patients with barium residues in the esophagus after VFSS through HREM. According to previous studies of timed barium esophagogram, an esophageal diameter 4 cm after 1 minute form barium swallowing suggested the possibility of achalasia, whereas a barium diameter greater than 1 cm suggested nonachalasia motility disorder [8,9]. We hypothesized that there would be esophageal motility disorders in patients with post-VFSS barium residues greater than 1 cm. In addition, we hypothesized that a significant number of patients undergoing the VFSS test may have difficulties in receiving the HREM due to pre-existing cognitive or physical impairments [6]. In this study, we aimed to confirm the presence of esophageal motility disorders by reviewing the results of HREM in subjects with a diameter of 1 cm or more of barium residue in the esophagus, and to determine the proportion of major motility disorders requiring active treatment attempts. We also aimed to analyze the proportion of those who did not receive the HREM and the reasons of HREM failures.

Esophageal evaluations including HREM were performed to assess the esophageal motility disorders. The proportion of esophageal motility disorders was 68.8%. Major and minor esophageal motility disorders were 18.8% and 50%, respectively. This was the first study to analyze the proportion of esophageal motility disorders through HREM in patients with esophageal barium residues with diameter greater than 1 cm on the post-VFSS chest X-ray. Of the 85 patients with esophageal barium residues, only 16 underwent HREM testing, and the remaining 81% did not achieve HREM testing. Characteristics such as age, causative disease, MMSE, MBI, and VFSS findings excluding sex, were not significantly different between successful and failed HREMs. In spite of low execution rate of HREM, our findings suggest that esophageal motility disorders may be present in a high proportion in patients with large residual barium on post-VFSS chest X-rays.

In this analysis, the proportion of subjects with esophageal barium greater than 1 cm was 19% of the subjects, which was even higher than the previously reported 7.5% with presence of esophageal barium residue regardless of the size of diameter [6]. The previous study showed significant differences in the age of subjects based on the presence or absence of esophageal barium residues [6]. The average age of the study population in the previous study was 73.5 years, and the age of population in this study was slightly older (mean age was 74.7 years). The proportion of esophageal abnormalities may vary depending on the characteristics of the patients (e.g., age) participating in the VFSS. Therefore, it suggests that the rate of esophageal dysphagia among people receiving VFSS test may vary by hospitals or regions. Nevertheless, we were able to suggest that a non-negligible proportion of VFSS patients could have esophageal dysphagia.

In spite of the high proportion of identified causes of esophageal dysphagia (87.5%) including 11 motility and three structural disorders, two patients showed unspecified findings on HREM and EGD. In the current study, VFSS was performed in an upright posture and HREM was performed supine. Sweis et al. [18] reported that in the upright position, the pressure of the EGJ could change due to an increase in hydrostatic pressure or anatomical change. When upright position swallows were included in the HREM, the results could be different to a supine test [19]. Generally, esophageal motility disorders are associated with both solid foods and liquids [3]. HREM with solid food had different findings than that with liquid food. Sweis et al. [18] reported that the integrated relaxation pressure was larger in solid swallows than in liquid ones because of increased friction between the bolus and the luminal wall. Our HREM protocol was to swallow liquid (thin or thick). When solid food swallowing or upright position swallow were included in the HREM, the results could differ a from liquid and supine test [19]. The Chicago classification, which classified esophageal motility disorders through HREM, was published in version 3.0 in 2015 and updated to version 4.0 in 2020. In the Chicago classification version 4.0, positional change (supine and upright position) and provocative testing (solid food) were included [20]. Because the Chicago classification version 4.0 provides detailed diagnostic threshold values for upright position and solid food swallowing, more accurate diagnosis will be possible if HREM is based on the Chicago classification version 4.0. At the time of our study, the Chicago classification version 3.0 was the latest version, so the upright position test or the solid food test could not be performed.

Previous study suggested the larger diameter barium in the esophagus could be associated with achalasia compared to non-achalasia motility disorders [8,9]. In our study, the diameter and end-level of esophageal residual barium were not significantly related to the severity of esophageal motility disorders. First, this may be because only large barium residues (diameter ≥1 cm) were included in the analysis. Second, too few patients were included, and it may have failed to achieve statistical significance due to the small sample. Third, this may be due to the failure to control the interval between VFSS and chest X-ray. The interval between two tests may increase, depending on several factors. When large amounts of pharyngeal residues were observed during VFSS, oropharyngeal suction was performed during or after VFSS. Depending on the patient’s walking ability, the travel time to the chest X-ray room after VFSS could be delayed.

Sixty-nine of 85 patients (81%) failed HREM. Poor cooperation was the most common cause of failed HREM. The conventional HREM protocol (based on Chicago classification version 3.0), which requires 10 swallows of 5 mL of liquid in the supine position [7], was difficult to perform in patients who did not cooperate. Shinjo et al. [21] reported that swallowing was subjectively more difficult in the supine position than in the upright position. Xiao et al. [19] reported that the diagnostic results were significantly consistent in the supine and upright positions. Therefore, for patients with risk of aspiration and poor cooperation, carefully performing only five swallows in the upright position can be considered.

This study has several limitations. First, it was a retrospective review, and additional workups were not performed in the absence of esophageal barium residue or with small residue. Therefore, a randomized controlled trial is needed to determine whether there is a statistically significant difference in the diagnostic rate of esophageal dysphagia by performing additional workups in a control group without esophageal barium residue. Second, of 85 patients with large esophageal barium residue, only 16 patients underwent esophageal evaluation. The sample was too small to evaluate the relationship between the degree of barium diameter and the severity of esophageal motility disorders. Third, chest X-ray posture was not consistent. Patients (n=25) who were able to stand were examined with the chest posteroanterior (PA) to observe a wider lung field. However, the patient (n=60) with difficulty in standing was examined in anteroposterior (AP) method because there was a risk of falling. We could not find any papers reporting the difference in esophageal diameter between chest PA and chest AP, but there may be a bias in measuring barium diameter.

In conclusion, of the 85 patients with large esophageal residual barium, 16 (18.8%) successfully underwent HREM. Lack of cooperation, systemic deterioration, and other medical reasons were the most common reasons limiting HREM. Esophageal motility disorders were identified in 68.8% of 16 patients with large esophageal residual barium with three patients in the major and eight patients in the minor categories. Including three patients (18.8%) with structural disorders, the proportion of identified causes of esophageal dysphagia was increased up to 87.5%. Since residual barium in the esophagus is not rare and can be a sign of significant esophageal disease, additional esophageal evaluation will be required.