Esophageal Body Motility for Clinical Assessment in Patients with Refractory Gastroesophageal Reflux Symptoms

Esophageal chemical clearance and mucosa integrity values in refractory gastroesophageal reflux disease patients with different esophageal dynamics

OBJECTIVES

Esophageal post-reflux swallow-induced peristaltic wave index (PSPWI) and mean nocturnal baseline impedance (MNBI), novel impedance-based markers of reflux burden, are associated with esophageal dynamics. We aim to investigate the characteristics of PSPWI and MNBI in Chinese refractory gastroesophageal reflux disease (RGERD) patients with different esophageal dynamic changes.

MATERIALS AND METHODS

201 RGERD and 76 functional heartburn patients, undergone off-PPI endoscopy, esophageal manometry and impedance-pH monitoring, were included. Comparisons of conventional and novel impedance-pH metrics were made among different esophageal dynamics groups. Receiver operating-characteristic analyses were utilized to evaluate the diagnostic efficacy of PSPWI and MNBI in differentiating abnormal esophageal dynamics. Correlations were used to investigate their associated factors.

RESULTS

PSPWI and MNBI of RGERD with esophagogastric junction (EGJ) injury and esophageal dysmotility were lower than EGJ injury alone or normal dynamics (p < 0.05 for both comparisons). PSPWI with esophageal peristalsis abnormality was lower than EGJ injury (p = 0.049), while MNBI showed no statistical difference. PSPWI, MNBI and their combination have auxiliary diagnostic values for esophageal peristalsis [area under the curves (AUCs): 0.683, 0.656, 0.708)] while only their combination for EGJ injury (AUC: 0.610). And they positively correlated with esophageal motility while negatively correlated with ineffective swallows and acid reflux events.

CONCLUSIONS

PSPWI and MNBI, indicating impairment of esophageal chemical clearance and mucosa integrity, were lower in RGERD patients with multiple esophageal dynamic injuries than single injuries or normal dynamics. Moreover, they provided useful contributing information for potential dynamic injuries if manometry has already been found normal or marginal.

Clinical efficacy and mechanism of transcutaneous neuromodulation on ineffective esophageal motility in patients with gastroesophageal reflux disease

BACKGROUND

Esophageal motility disorder is one of the pathogenesis of gastroesophageal reflux disease (GERD). The clinical and functional relationship between the ineffective esophageal motility (IEM) and GERD have been found. PPI is a widely used drug of this diaease, but some patients have poor efficacy. The purpose of this study was to investigate the efficacy and possible mechanism of Transcutaneous Neuromodulation in these patients.

METHODS

Fifty-six patients with GERD with IEM were enrolled and randomly divided into two groups, one group was TN ST-36 group, the other group was sham TN group. The GERD questionnaire (GerdQ), quality of life score, MOS item short from health survey (SF-36), Hospital Anxiety and Depression Scale (HADS) were used to assess the severity of symptoms. High-resolution esophageal manometry (HRM) test was performed to assess low esophageal sphincter (LES) pressure and distal contractile integral (DCI). The heart rate variability (HRV) test was performed to assess autonomic nervous function.

KEY RESULTS

Compared with sham TN, chronic TN treatment decreased the GERD-Q score (p < 0.001). The anxiety score (p = 0.058) and depression score (p = 0.156) were decreased, but there were no statistical differences. Chronic TN treatment also significantly improved the quality of life of patients, mainly in physical function, physical pain, overall health, vitality, social function, emotional function, and mental health. Acute TN treatment increased the DCI (p < 0.001) and LES pressure (p < 0.001) significantly and decreased the combined percentage of failed and weak peristalsis (p < 0.001). Concurrently, acute TN enhanced vagal activity (p < 0.001).

CONCLUSIONS AND INFERENCES

IEM is an important link in the pathogenesis of GERD. Chronic TN treatment can significantly improve the clinical symptoms of patients. Acute TN treatment can significantly increase LES pressure and DCI and reduce the frequency of esophageal lost peristalsis and weak peristalsis. The improvement of esophageal motility in GERD patients with IEM by TN treatment may be related to the regulation of autonomic nervous function.

Updates in interaction of gastroesophageal reflux disease and extragastroesophageal digestive diseases

INTRODUCTION

Gastroesophageal reflux disease (GERD) is one of the common chronic diseases with prevalence increasing in the last decades. Because of its prevalence and chronicity, GERD affects the quality of life and increases health-care costs. Gastroesophageal diseases leading to GERD have been thoroughly studied, while extragastroesophageal digestive diseases (EGEDDs) may coexist with GERD and affect the occurrence and persistence of GERD symptoms and therapeutic effect.

AREAS COVERED

In this review, we aim to summarize the EGEDDs correlated with GERD and explore the potential mechanisms of this interaction.

EXPERT OPINION

Individuals with troublesome GERD symptoms may have some common gastroesophageal etiologies, but EGEDDs may also overlap and impact on the progression of GERD, which are often ignored in clinic. The lesions in the small intestine, colon, and hepatobiliary tract as well as functional bowel disorders had positive or negative associations with GERD through potential mechanisms. These diseases aggravate GERD symptoms, increase the esophageal acid burden, cause esophageal hypersensitivity, and finally affect the response to therapy in GERD patients. Therefore, it is necessary to clear the interaction between GERD and EGEDDs and their mechanisms.

Concise Review: Applicability of High-resolution Manometry in Gastroesophageal Reflux Disease

Manometry, particularly high-resolution manometry is the preferred diagnostic tool used to evaluate esophageal motor function. This investigation is strongly indicated in the setting of dysphagia, but is also useful in gastroesophageal reflux disease (GERD), especially in case of failure of conventional treatment to exclude alternative diagnoses and prior to anti-reflux surgery. Moreover, ineffective esophagogastric junction barrier function and esophageal motor dysfunction are pathophysiological mechanisms in GERD and can be identified by manometry. The recent international guidelines have positioned high-resolution manometry as an important part of functional diagnostic work up in GERD in order to identify the GERD phenotype to guide specific treatment. The proposed manometric identification and measurement is based on the Chicago classification version 4.0 adding with new established metrics for GERD evaluation.

GERD-related chronic cough: Possible mechanism, diagnosis and treatment

GERD, or gastroesophageal reflux disease, is a prevalent medical condition that affects millions of individuals throughout the world. Chronic cough is often caused by GERD, and chronic cough caused by GER is defined as GERD-related chronic cough (GERC). It is still unclear what the underlying molecular mechanism behind GERC is. Reflux theory, reflex theory, airway allergies, and the novel mechanism of esophageal motility disorders are all assumed to be linked to GERC. Multichannel intraluminal impedance combined with pH monitoring remains the gold standard for the diagnosis of GERC, but is not well tolerated by patients due to its invasive nature. Recent discoveries of new impedance markers and new techniques (mucosal impedance testing, salivary pepsin, real-time MRI and narrow band imaging) show promises in the diagnosis of GERD, but the role in GERC needs further investigation. Advances in pharmacological treatment include potassium-competitive acid blockers and neuromodulators (such as Baclofen and Gabapentin), prokinetics and herbal medicines, as well as non-pharmacological treatments (such as lifestyle changes and respiratory exercises). More options have been provided for the treatment of GERC other than acid suppression therapy and anti-reflux surgery. In this review, we attempt to review recent advances in GERC mechanism, diagnosis, and subsequent treatment options, so as to provide guidance for management of GERC.

Esophageal Nocturnal Baseline Impedance and Post-reflux Swallow-induced Peristaltic Wave Index in Identifying Proton Pump Inhibitor-refractory Non-erosive Reflux Disease

Background/Aims

Esophageal mean nocturnal baseline impedance (MNBI) levels and post-reflux swallow-induced peristaltic wave (PSPW) index could increase the diagnostic value of 24-hour multichannel intraluminal impedance and pH monitoring in patients with gastroesophageal reflux disease. This study aims to compare the MNBI and PSPW index in patients with no evidence of erosive reflux disease.

Methods

Impedance-pH monitoring tracings from 70 patients, 50 with non-erosive reflux disease (NERD) and 20 with functional heartburn (FH), were reviewed. According to proton pump inhibitors (PPI) treatment response, NERD patients were divided into NERD/PPI responders and NERD/PPI nonresponders. MNBI, PSPW index, and intercellular spaces were measured and compared among each group.

Results

MNBI values and PSPW index were lower in NERD patients than in FH (P < 0.01 and P < 0.05, respectively). MNBI positively correlated with PSPW index (r = 0.525, P < 0.001). NERD/PPI responders had lower MNBI values and PSPW index compared to NERD/PPI nonresponders (both P < 0.01). MNBI and PSPW index distinguished NERD from FH patients with an area under the curve of 0.914 and 0.677, respectively. Wider intercellular space could be identified in patients with NERD (P < 0.01).

Conclusion

MNBI and PSPW index may differentiate NERD from FH patients and relate to PPI treatment efficacy in patients with NERD.

Esophagogastric junction contractile integral abnormalities in patients with proton pump inhibitor-refractory symptoms

OBJECTIVES

Esophagogastric junction contractile integral (EGJ-CI) is a novel indicator to evaluate quantitatively the esophagogastric junction (EGJ) barrier function. We aimed to assess the role of EGJ-CI in patients with refractory gastroesophageal reflux disease (GERD) symptoms and the correlation between EGJ-CI and impedance-pH monitoring characteristics.

METHODS

In total 82 patients with proton pump inhibitors (PPIs)-refractory gastroesophageal reflux symptoms (heartburn or regurgitation) were enrolled. These patients were further divided into two groups based on their EGJ-CI value (39 mmHg·cm). The mean nocturnal baseline impedance (MNBI) was measured to explore its association with EGJ-CI.

RESULTS

The median EGJ-CI in patients with PPI-refractory symptoms was 30.8 mmHg·cm. EGJ-CI was inversely correlated with acid exposure time and reflux episodes; while it was positively correlated with MNBI, distal contractile integral, lower esophageal sphincter basal pressure and integrated relaxation pressure. Patients were further divided into the high (n = 27) and low (n = 55) EGJ-CI groups using a cut-off value of 39.0 mmHg·cm. Patients with a low EGJ-CI had a lower MNBI level than those with a high EGJ-CI (2703 Ω vs 3545 Ω, P = 0.034).

CONCLUSIONS

In patients with PPIs-refractory symptoms, EGJ-CI is associated with acid exposure and conventional high-resolution manometry parameters. EGJ-CI may play an important role in the diagnosis and treatment of patients with refractory GERD.

Integrative Effects and Vagal Mechanisms of Transcutaneous Electrical Acustimulation on Gastroesophageal Motility in Patients With Gastroesophageal Reflux Disease

INTRODUCTION

Impaired esophageal and gastric motilities are known to contribute to symptoms of gastroesophageal reflux disease (GERD). However, there is a lack of GERD therapy, targeting both gastric and esophageal functions. This study was designed to investigate the effects of transcutaneous electrical acustimulation (TEA) on symptoms of GERD and gastroesophageal functions and possible mechanisms in patients with GERD.

METHODS

Thirty patients with GERD with ineffective esophageal motility were equally divided and randomized into a 4-week sham-TEA or 4-week TEA treatment. The GERD questionnaire (GerdQ), GERD health-related quality-of-life questionnaire, high-resolution esophageal manometry, a nutrient drink test, the electrogastrogram, and ECG were performed to assess the severity of reflux symptoms, low esophageal sphincter (LES) pressure, distal contractile integral (DCI), gastric accommodation, gastric slow waves (GSW), and autonomic functions, respectively.

RESULTS

Compared with sham-TEA, the 4-week TEA treatment significantly decreased the GerdQ score (P = 0.011) and GERD health-related quality of life (P = 0.028) and improved nutrient drink-induced fullness (P < 0.001) and belching (P < 0.001) in patients with GERD. Although only acute TEA significantly enhanced LES pressure (P < 0.05), both acute and chronic TEA remarkedly increased DCI (P < 0.05) and reduced the incidence of ineffective esophageal contractions during wet swallows (P = 0.02). In addition, chronic TEA significantly increased gastric accommodation and the percentage of postprandial normal GSW compared with sham-TEA and baseline. Concurrently, TEA-enhanced vagal activity (P = 0.02) and the vagal activity positively correlated with LES pressure (r = 0.528; P = 0.003) and DCI (r = 0.522; P = 0.003).

DISCUSSION

The TEA treatment performed in this study improves reflux-related symptoms, increases DCI, reduces the incidence of ineffective esophageal contractions during wet swallows, and improves gastric accommodation and slow waves. The improvement in GERD symptoms might be attributed to the integrative effects of TEA on these gastroesophageal functions mediated via the vagal mechanism.

Manometric and pH-monitoring changes after laparoscopic sleeve gastrectomy: a systematic review

PURPOSE

Aim of this systematic review is to assess the changes in esophageal motility and acid exposure of the esophagus through esophageal manometry and 24-hours pH-monitoring before and after laparoscopic sleeve gastrectomy (LSG).

METHODS

Articles in which all patients included underwent manometry and/or 24-hours pH-metry or both, before and after LSG, were included. The search was carried out in the PubMed, Embase, Cochrane, and Web of Science databases, revealing overall 13,769 articles. Of these, 9702 were eliminated because they have been found more than once between the searches. Of the remaining 4067 articles, further 4030 were excluded after screening the title and abstract because they did not meet the inclusion criteria. Thirty-seven articles were fully analyzed, and of these, 21 further articles were excluded, finally including 16 articles.

RESULTS

Fourteen and twelve studies reported manometric and pH-metric data from 402 and 547 patients, respectively. At manometry, a decrease of the lower esophageal sphincter resting pressure after surgery was observed in six articles. At 24-hours pH-metry, a worsening of the DeMeester score and/or of the acid exposure time was observed in nine articles and the de novo gastroesophageal reflux disease (GERD) rate that ranged between 17.8 and 69%. A meta-analysis was not performed due to the heterogeneity of data.

CONCLUSIONS

After LSG a worsening of GERD evaluated by instrumental exams was observed such as high prevalence of de novo GERD. However, to understand the clinical impact of LSG and the burden of GERD over time further long-term studies are necessary.

Gastroesophageal reflux and asthma: when, how, and why

PURPOSE OF REVIEW

Gastro-esophageal reflux is a possible cause of uncontrolled symptoms of asthma and should be actively investigated and treated before severe asthma is diagnosed and biological therapy started.

RECENT FINDINGS

Recent investigations on esophageal function and tissue biomarkers in patients with asthma and associated GERD have established a relevant role for esophageal motility and neuronal sensory abnormalities in linking the two diseases. Characterization of the underpinning inflammatory substrate has showed mixed results as both neutrophilic and eosinophilic type 2 inflammatory changes have been described.

SUMMARY

New findings regarding inflammatory mechanisms in GERD-associated asthma as well as new diagnostic tools to investigate functional esophageal abnormalities and characterize asthma endotype have identified potential treatable traits that may improve the clinical management and outcome of asthmatic patients with GERD.

[Esophageal pH-impedance monitoring of reflux patterns in non-erosive reflux disease, reflux hypersensitivity and functional heartburn]

OBJECTIVE

To analyze the differences in reflux patterns in 24-hour esophageal pH-impedance monitoring in patients with non-erosive reflux disease (NERD), reflux hypersensitivity (RH) and functional heartburn (FH) and explore the possible mechanism of symptoms in patients with heartburn and negative endoscopic findings.

METHODS

Seventy-nine patients with heartburn as the main symptoms but negative endoscopic findings, including 35 with NERD, 16 with RH and 28 with FH, were enrolled in this study.All the patients underwent 24-h esophageal pH-impedance monitoring and esophagogastroscopy, and the results were compared among the 3 groups.

RESULTS

Acid reflux episode was significantly increased and weakly alkaline reflux episode was significantly decreased in NERD group in comparison with RH group and FH group (P < 0.05).The patients in NERD group showed significantly increased total reflux episode, mixed reflux episode, proximal acid reflux episode, proximal weak acid reflux episode, total proximal reflux episode, percentage of proximal acid reflux, percentage of proximal weak acid reflux, and percentage of total proximal reflux as compared with the other two groups (all P < 0.05).Bolus clear time was significantly prolonged in NERD group compared with that in the other two groups (P < 0.05).Analysis of the reflux acidity showed that the percentages of different reflux episodes differed significantly among the 3 groups (P < 0.05);acid reflux was the main reflux in NERD, while weak acid reflux was the main reflux in RH and FH groups, which had also significantly increased weakly alkaline reflux episodes compared with NERD group.

CONCLUSIONS

Patients with NERD, RH and FH had different reflux patterns.Acid reflux is predominant in the NERD, while weakly alkaline reflux is significantly increased RH and FH.In patients with normal esophageal acid exposure but without symptoms or without recorded symptoms during esophageal pH-impedance monitoring, analysis of the total reflux episode, mixed reflux episode, proximal acid reflux episode and percentage can help in the differential diagnosis between RH and FH.

Impact of ineffective esophageal motility on chemical clearance in patients with gastroesophageal reflux symptoms

Ineffective esophageal motility (IEM) is the most common manometric abnormality in gastroesophageal reflux disease (GERD). However, the impact of IEM on esophageal chemical clearance has not been fully investigated. This study aimed to determine the impact of IEM on esophageal chemical clearance in patients with GERD. A total of 369 patients with GERD symptoms who underwent upper endoscopy and high-resolution manometry (HRM) test were retrospectively analyzed. The relationship between IEM and erosive esophagitis was examined. In addition, the impact of IEM on chemical clearance was examined in patients who underwent an additional combined multichannel intraluminal impedance-pH (MII-pH) test. Esophageal chemical clearance capability was evaluated via postreflux swallow-induced peristaltic wave (PSPW) index and acid clearance time (ACT). Of 369 patients, 181 (49.1%) had esophageal motility disorders, of which 78 (21.1%) had IEM. The proportion of IEM patients in those with erosive esophagitis and those without were 16.2% and 21.7%, respectively, and no significant difference was observed (P = 0.53). After excluding patients other than those with IEM and normal esophageal motility, 64 subsequently underwent MII-pH test. The median values of the PSPW index in the IEM and normal esophageal motility group were 11.1% (4.2%-20.0%) and 17.1% (9.8%-30.6%), respectively. The PSPW index was significantly lower in the IEM group than in the normal esophageal motility group (P < 0.05). The median ACT values in the IEM group and normal esophageal motility group were 125.5 (54.0-183.5) seconds and 60.0 (27.2-105.7) seconds, respectively. The ACT was significantly longer in the IEM group than in the normal esophageal motility group (P < 0.05). In conclusion, IEM was found to be associated with chemical clearance dysfunction as measured against the PSPW index and ACT. As this condition could be a risk factor for GERD, future treatments should be developed with a focus on chemical clearance.

Gastroesophageal reflux disease and chronic cough: A possible mechanism elucidated by ambulatory pH-impedance-pressure monitoring

BACKGROUND

The pathophysiological mechanism(s) of gastroesophageal reflux disease (GERD)-related chronic cough (CC) is unclear. We aimed to determine the mechanism of reflux-induced cough by synchronous monitoring of reflux episodes, esophageal motility, and cough.

METHODS

Patients with GERD were prospectively enrolled and classified into GERD with CC (GERD-CC) and without CC (GERD) groups. Twenty-four-hour ambulatory pH-impedance-pressure monitoring was performed; the reflux patterns, esophageal motility during prolonged exposure to acid and characteristics of reflux episodes that induced coughing paroxysms were analyzed.

KEY RESULTS

Thirty-one patients with GERD-CC and 47 with GERD were enrolled; all of whose monitoring results fulfilled the criteria for diagnosis of GERD. Patients with GERD-CC had higher reflux symptom scores, longer exposure to acid, higher DeMeester scores, and more frequent reflux episodes, proximal extent reflux detected by impedance, and higher percentage of strongly acidic reflux than patients in the GERD group (all P < .05). Of 63 reflux-cough episodes identified in the GERD-CC group, 74.6% of distal reflux and 67.0% of proximal reflux episodes were acidic. More patients had low pan-esophageal pressure in primary peristalsis (48.5% vs 11.8%, P = .000) and synchronous contraction in secondary peristalsis during prolonged exposure to acid in the GERD-CC than in the GERD group (63.9% vs 9.1%, P = .000).

CONCLUSIONS & INFERENCES

Proximal acidic reflux and distal reflux-reflex are jointly associated with reflux-induced cough in patients with GERD. Low pan-esophageal pressure in primary peristalsis and synchronous contraction in secondary peristalsis may play important roles in GERD-associated chronic cough.

Esophageal Motor Dysfunctions in Gastroesophageal Reflux Disease and Therapeutic Perspectives

Gastroesophageal reflux disease (GERD) is a very common disease, and the prevalence in the general population has recently increased. GERD is a chronic relapsing disease associated with motility disorders of the upper gastrointestinal tract. Several factors are implicated in GERD, including hypotensive lower esophageal sphincter, frequent transient lower esophageal sphincter relaxation, esophageal hypersensitivity, reduced resistance of the esophageal mucosa against the refluxed contents, ineffective esophageal motility, abnormal bolus transport, deficits initiating secondary peristalsis, abnormal response to multiple rapid swallowing, and hiatal hernia. One or more of these mechanisms result in the reflux of stomach contents into the esophagus, delayed clearance of the refluxate, and the development of symptoms and/or complications. New techniques, such as 24-hour pH and multichannel intraluminal impedance monitoring, multichannel intraluminal impedance and esophageal manometry, high-resolution manometry, 3-dimensional high-resolution manometry, enoscopic functional luminal imaging probe, and 24-hour dynamic esophageal manometry, provide more information on esophageal motility and have clarified the pathophysiology of GERD. Proton pump inhibitors remain the preferred pharmaceutical option to treat GERD. The ideal target of GERD treatment is to restore esophageal motility and reconstruct the anti-reflux mechanism. This review focuses on current advances in esophageal motor dysfunction in patients with GERD and the influence of these developments on GERD treatment.

High-Resolution Manometry Diagnosis of Ineffective Esophageal Motility Is Associated with Higher Reflux Burden

INTRODUCTION

Ineffective esophageal motility (IEM) is the most commonly diagnosed abnormality on high-resolution manometry (HRM). However, the clinical significance of IEM and associated reflux burden remains unclear.

AIM

Our primary aim was to compare reflux patterns between IEM versus normal motility on HRM.

METHODS

HRM and reflux studies in patients with IEM and normal motility were retrospectively reviewed. Esophageal pressure topography parameters, reflux variables, and patient-reported outcome questionnaires were explored.

RESULTS

A total of 239 patients with IEM were explored. Of these, 146 underwent reflux monitoring. Additionally, 100 patients with normal HRM all of whom had undergone reflux monitoring were included. IEM patients were more likely to have an abnormal number of reflux events compared to normal (22.7% vs. 9.0%, p < 0.01). Including only off-proton pump inhibitor (PPI) testing, IEM patients had higher mean total acid exposure time (AET) and total reflux events compared to normal motility (p = 0.02). Within IEM patients, higher AET modestly correlated with increased percentage of impaired swallows. Increased reflux events modestly correlated with higher impaired swallows and decreased lower esophageal sphincter (LES) resting pressure. Reflux burden increased with higher esophagogastric junction (EGJ) subtype, driven mostly by subtype III, although there was no difference in the distribution of EGJ subtypes between the IEM and normal HRM cohorts.

CONCLUSIONS

Patients with HRM diagnosis of IEM may be more prone to acid reflux while off-PPI and non-acid reflux while on-PPI. Reflux burden appears to be worse in IEM patients who have lower resting LES pressure, higher EGJ subtype, or higher percentage of impaired swallows.

Acid exposure in patients with gastroesophageal reflux disease is associated with esophageal dysmotility

OBJECTIVE

To explore the correlation between reflux disease and abnormal esophageal motility in patients with gastroesophageal reflux disease (GERD).

METHODS

Participants (patients with GERD and controls) who underwent 24-h impedance-pH monitoring (MII-pH monitoring) and high-resolution manometry between January 2012 and February 2017 were retrospectively studied. The patients were divided into two groups (acid reflux and nonacid reflux) based on their MII-pH monitoring data. Reflux episodes, endoscopic findings, and esophageal dynamic parameters were assessed and compared.

RESULTS

A total of 142 patients were included (acid reflux [n = 58], nonacid reflux [n = 60], control group [n = 24]). There were more patients with esophagitis and more severe esophageal mucosal injury in the acid reflux group than in the nonacid reflux group. The acid reflux group had reduced lower esophageal sphincter (LES) basal pressure, shorter LES length, lower esophageal pressure and distal contractile integral index than the nonacid reflux group. Patients in the acid reflux group had more large breaks and a higher incidence of type II and III esophagogastric junction morphology than those in the nonacid reflux group. Acid exposure time, the incidence of long-term acid reflux, recumbent acid reflux, and the incidence of acid and nonacid reflux had a significant negative correlation with esophageal body motility or LES function.

CONCLUSION

This study suggests that an increase in esophageal acid exposure is correlated with an increase in esophageal dysmotility in patients with GERD.