With the introduction of esophageal high-resolution manometry (HRM) in the 1990s, the assessment of patients with dysphagia has been facilitated compared to conventional esophageal manometry. Esophageal HRM is now established as the gold standard method for diagnosing esophageal motility disorders. The publication and update of the Chicago classification (CC) further solidified the importance of HRM in the diagnosis of esophageal motility disorders. However, the limitation of HRM is that it cannot furnish information about bolus transit, a conclusion based on studies integrating manometry with the radiological visualization of flow and clearance.¹

More recently, esophageal high-resolution impedance manometry (HRIM), which combines HRM and impedance, has been developed and used to diagnose patients with dysphagia. HRIM has the advantage of providing both HRM metrics and impedance-based bolus transit patterns simultaneously.² Usually, patients with esophageal motility disorders have both abnormalities in bolus clearance and abnormalities in HRM metrics. However, in some patients, HRM metrics are normal, and only bolus clearance is incomplete in impedance, or bolus clearance is complete, and only HRM metrics are abnormal. In these cases, it becomes difficult for physicians to interpret the HRIM results.³

Even the CC, the HRM interpretation criteria for diagnosing esophageal motility disorders, rarely address the transport of bolus contents on impedance. In the recently published CC version 4.0, the supportive role of bolus transit on impedance is only slightly described in the diagnosis of ineffective esophageal motility (IEM) section.⁴ Regarding impedance values, even though bolus transit is one of the important measures of impedance, there is no consensus on the management of incomplete bolus clearance.⁵

In an issue of the Journal of Neurogastroenterology and Motility, Dorfman et al⁶ reported a cross-sectional anonymous e-mail survey study conducted to identify trends in HRIM metrics interpretation by gastroenterologists worldwide. A questionnaire was created exclusively for the study. The questionnaire consisted of 10 questions, including basic information about the respondents and about coping with situations where HRM metrics and bolus transit results differed. A total of 107 gastroenterologists from 26 countries responded, and 65.5% of the respondents were adult providers. While most respondents found HRIM useful (yes: 77.6%, sometimes: 20.6%), most of the respondents reported that they had experienced a discrepancy between HRM metrics and impedance values (often: 31.8%, rarely: 66.4%). Interestingly, when HRIM results showed incomplete bolus clearance and normal manometry, 38.7% recommended observation, 38.7% recommended 24-hour pH-impedance, and 15.1% recommended prokinetics. When the HRIM results showed abnormal manometry and complete bolus clearance, 57.1% recommended observation, while 17.1% recommended 24-hour pH-impedance and 14.3% recommended prokinetics. Although there were significant differences in results when analyzing respondents by continent, there were no significant differences in results regarding specialty (adult providers vs pediatric providers) or years of clinical experience (less than 5 years vs more than 5 years).

The strength of the study is that, to the authors’ knowledge, there has never been a global study of gastroenterologists on discrepancies between HRM metrics and impedance values, including a survey study. However, most of the respondents were from North America (59.8%) and Europe (16.8%), with relatively few respondents from Asia (5.6%), Oceania (8.4%), and South America (9.3%). Therefore, it is unlikely that the results of this study reflect global management trends when HRM metrics and impedance values are different.

In situations when bolus clearance and manometry study results were discordant, the respondents were more likely to perform additional testing or treatment if they observed incomplete bolus clearance than if they observed abnormal esophageal manometry study results. Zerbib et al⁷ performed a study to investigate motility patterns and symptoms related to IEM, defined as impaired bolus clearance. Although the proportion was small, 6.8% of the asymptomatic controls in HRM were diagnosed with IEM based on CC version 3.0, and all 28 initially enrolled IEM patients had incomplete bolus clearance.⁷ In terms of bolus clearance, the median percentage of swallows with complete bolus clearance was 95%, with a normal range defined by 5th and 95th centiles of 50-100%.⁷ Between bolus clearance and HRM metrics, bolus clearance is arguably a more physiologic indicator than HRM metrics. Thus, it seems that the respondents consider bolus clearance to be more reflective of the patient’s symptoms.

Concerning prescribing anti-reflux therapy and prokinetics, when asked about patients with normal esophageal manometry studies with incomplete bolus clearance, 1.9% of the respondents selected anti-reflux therapy, and 15.1% selected prokinetics. When asked about patients with abnormal esophageal manometry studies with complete bolus clearance, 6.7% of the respondents selected anti-reflux therapy, and 14.3% selected prokinetics. Among the patients who underwent HRIM for esophageal symptoms, the discrepancy between bolus clearance and manometry study results would include patients with minor esophageal motility disorders, such as IEM, as covered in CC version 3.0 and version 4.0.^8,9 Since IEM is often combined with gastroesophageal reflux disease (GERD), the mainstay of treatment is proton pump inhibitors (PPIs) or prokinetics, and in patients with refractory GERD, prokinetics may be added to PPIs.^8,10,11 A recent meta-analysis study including 16 randomized control trials reported that PPIs with prokinetics showed a significant reduction in global GERD symptoms regardless of the prokinetic type, refractoriness, or ethnicity compared to PPI monotherapy (risk ratio of reflux symptoms resolution, 1.22; 95% confidence interval, 1.11 to 1.35; P < 0.0001).¹² Mosapride improved esophageal symptoms and significantly enhanced distal contractile integral in a study by Kim et al¹³ The medical approach should be determined by the patient’s symptoms. However, it seems that medication may be considered if symptoms are present.

This study is valuable in that it covers real-world clinical challenges and issues faced by physicians treating patients with esophageal motility disorders. Hopefully, future updated guidelines for esophageal motility disorders will address impedance value criteria or alternatives to overcome the discrepancy between bolus clearance and manometry study results.

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