Morphometric evaluation of oesophageal wall in patients with nutcracker oesophagus and ineffective oesophageal motility

Esophageal anatomy and physiology vary across spastic and non-spastic phenotypes of disorders of esophagogastric junction outflow

BACKGROUND

Pathophysiologic mechanisms of disorders of esophagogastric junction (EGJ) outflow are poorly understood. We aimed to compare anatomic and physiologic characteristics among patients with disorders of EGJ outflow and normal motility.

METHODS

We retrospectively evaluated adult patients with achalasia types 1, 2, 3, EGJ outflow obstruction (EGJOO) or normal motility on high-resolution manometry who underwent endoscopic ultrasound (EUS) from January 2019 to August 2022. Thickened circular muscle was defined as ≥1.6 mm. Characteristics from barium esophagram (BE) and functional lumen imaging probe (FLIP) were additionally assessed.

KEY RESULTS

Of 71 patients (mean age 56.2 years; 49% male), there were 8 (11%) normal motility, 58 (82%) had achalasia (5 (7%) type 1, 32 (45%) classic type 2, 21 (30%) type 3 [including 12 type 2 with FEPs]), and 7 (7%) had EGJOO. A significantly greater proportion of type 3 achalasia had thickened distal circular muscle (76.2%) versus normal motility (0%; p < 0.001) or type 2 achalasia (25%; p < 0.001). Type 1 achalasia had significantly wider mean maximum esophageal diameter on BE (57.8 mm) compared to type 2 achalasia (32.8 mm), type 3 achalasia (23.4 mm), EGJOO (15.9 mm), and normal motility (13.5 mm). 100% type 3 achalasia versus 0% type 1 achalasia/normal motility had tertiary contractions on BE. Mean EGJ distensibility index on FLIP was lower for type 3 achalasia (1.2 mmHg/mm2 ) and EGJOO (1.2 mmHg/mm2 ) versus type 2 (2.3 mmHg/mm2 ) and type 1 achalasia (2.9 mmHg/mm2 ).

CONCLUSIONS

Our findings suggest distinct pathologic pathways may exist: type 3 achalasia and EGJOO may represent a spastic outflow phenotype consisting of a thickened, spastic circular muscle, which is distinct from type 1 and 2 achalasia consisting of a thin caliber circular muscle layer with more prominent esophageal dilation.

Diagnostic methods to measure spastic segment and guide tailored myotomy length in type 3 achalasia

BACKGROUND

Myotomy length in type 3 achalasia is generally tailored based on segment of spasticity on high-resolution manometry (HRM). Potential of length of tertiary contractions on barium esophagram (BE) or length of thickened circular muscle on endoscopic ultrasound (EUS) to guide tailored myotomy is less understood. This study aimed to assess agreement between spastic segments lengths on HRM, BE, and EUS among patients with type 3 achalasia.

METHODS

This retrospective study included adults with type 3 achalasia on HRM between November 2019 and August 2022 who underwent evaluation with EUS and/or BE. Spastic segments were defined as HRM-distance between proximal borders of lower esophageal sphincter and high-pressure area (isobaric contour ≥70 mmHg); EUS-length of thickened circular muscle (≥1.2 mm) from proximal border of esophagogastric junction (EGJ) to the transition to a non-thickened circular muscle; BE-distance between EGJ to proximal border of tertiary contractions. Pairwise comparisons assessed for correlation (Pearson's) and intraclass correlation classification (ICC) agreement.

KEY RESULTS

Twenty-six patients were included: mean age 66.9 years (SD 13.8), 15 (57.7%) male. Spastic segments were positively correlated on HRM and BE with good agreement (ICC 0.751, [95% CI 0.51, 0.88]). Spastic segments were negatively correlated with poor agreement on HRM and EUS (ICC -0.04, [-0.45, 0.39]) as well as BE and EUS (ICC -0.03, [-0.47, 0.42]).

CONCLUSIONS & INFERENCES

Length of spastic segment was positively correlated on HRM and BE while negatively correlated when compared to EUS, supporting the common use of HRM and highlighting the uncertain role for EUS in tailoring myotomy length for type 3 achalasia.

Type II achalasia with focal elevated pressures: A distinct manometric and clinical sub-group

BACKGROUND

Type II achalasia (Ach2) is distinguished from other achalasia sub-types by the presence of panesophageal pressurization (PEP) of ≥30 mmHg in ≥20% swallows on high-resolution manometry (HRM). Variable manometric features in Ach2 have been observed, characterized by focal elevated pressures (FEPs) (focal/segmental pressures ≥70 mmHg within the PEP band) and/or high compression pressures (PEP ≥70 mmHg). This study aimed to examine clinical and physiologic variables among sub-groups of Ach2.

METHODS

This retrospective single center study performed over 3 years (1/2019-1/2022) included adults with Ach2 on HRM who underwent endoscopic ultrasound (EUS), functional lumen imaging probe (FLIP), and/or barium esophagram (BE) prior to therapy. Patients were categorized into two overarching sub-groups: Ach2 without FEPs and Ach2 with FEPs. Demographic, clinical, and physiologic data were compared between these sub-groups utilizing unpaired univariate analyses.

KEY RESULTS

Of 53 patients with Ach2, 40 (75%) were without FEPs and 13 (25%) had FEPs. Compared with the Ach2 sub-group without FEPs, the Ach2 sub-group with FEPs demonstrated a significantly thickened distal esophageal circular muscle on EUS (1.4 mm [SD 0.9] vs. 2.1 [0.7]; p = 0.02), higher prevalence of tertiary contractions on BE (46% vs. 100%; p = 0.0006), lower esophagogastric junction distensibility index (2.2mm2 /mmHg [0.9] vs 0.9 [0.4]; p = 0.0008) as well as higher distensive pressure (31.0 mmHg [9.8] vs. 55.4 [18.8]; p = 0.01) at 60 cc fill on FLIP, and higher prevalence of chest pain on Eckardt score (p = 0.03).

CONCLUSIONS AND INFERENCES

We identified a distinct sub-group of type II achalasia on HRM, defined as type II achalasia with focal elevated pressures. This sub-group uniquely exhibits spastic features and may benefit from personalized treatment approaches.

High-resolution esophageal manometry in a Mexican population: diagnostic outcome

High-resolution esophageal manometry (HREM) has become the method of choice for evaluation of esophageal motility disorders. There is a paucity of data with this technique from Hispanic countries. This study aims to characterize the diagnostic outcome of HREM in a large cohort of consecutive patients in Mexico.This study was conducted in Monterrey, Mexico from March 1, 2013 to March 31, 2015. Our diverse study population included patients from a major academic institution and the community. HREM was done applying the Chicago Classification 3. Diagnostic outcome was grouped as weak peristaltic disorders, gastroesophageal junction disorders, and hypertensive/uncoordinated peristalsis.We studied 670 consecutive patients, 57% were women, mean age was 43.8 years. The majority (465 [69%]) were referred for preoperative evaluation of gastroesophageal reflux disease (GERD), 365 (78%) of whom had a normal study. Overall, 193 (29%) patients had abnormal motility, the most common disorder being weak peristalsis (104 [54%]). In patients with dysphagia, the most frequent finding was achalasia (23/46 [50%]).To our knowledge, this is the first study to characterize the diagnostic outcome of HREM in a large cohort of Hispanic patients in Latin America. At our open access center, 69% of patients were referred for preoperative evaluation of GERD, reflecting the popularity of antireflux surgery. This study confirms the high prevalence of weak peristalsis and highlights the importance of addressing its pathophysiology and management. The finding of achalasia in 50% of our patients with dysphagia is consistent with recent reports regarding the rising incidence of this disorder and underscores the need of prompt motility testing in this population.

Mechanisms of repetitive retrograde contractions in response to sustained esophageal distension: a study evaluating patients with postfundoplication dysphagia

Repetitive retrograde contractions (RRCs) in response to sustained esophageal distension are a distinct contractility pattern observed with functional luminal imaging probe (FLIP) panometry that are common in type III (spastic) achalasia. RRCs are hypothesized to be indicative of either impaired inhibitory innervation or esophageal outflow obstruction. We aimed to apply FLIP panometry to patients with postfundoplication dysphagia (a model of esophageal obstruction) to explore mechanisms behind RRCs. Adult patients with dysphagia after Nissen fundoplication ( n = 32) or type III achalasia ( n = 25) were evaluated with high-resolution manometry (HRM) and upper endoscopy with FLIP. HRM studies were assessed for outflow obstruction and spastic features: premature contractility, hypercontractility, and impaired deglutitive inhibition during multiple-rapid swallows. FLIP studies were analyzed to determine the esophagogastric junction (EGJ)-distensibility index and contractility pattern, including RRCs. Barium esophagram was evaluated when available. RRCs were present in 8/32 (25%) fundoplication and 19/25 (76%) achalasia patients ( P < 0.001). EGJ outflow obstruction was detected in 21 (67%) fundoplication patients by HRM, FLIP, or esophagram [6 (29%) had RRCs]. On HRM, none of the fundoplication patients had premature contractility, whereas 3/4 with defective inhibition on multiple-rapid swallows and 2/4 with hypercontractility had RRCs. Regression analysis demonstrated HRM with spastic features, but not esophageal outflow obstruction, as a predictor for RRCs. RRCs in response to sustained esophageal distension appear to be a manifestation of spastic esophageal motility. Although future study to further clarify the significance of RRCs is needed, RRCs on FLIP panometry should prompt evaluation for a major motor disorder. NEW & NOTEWORTHY Repetitive retrograde contractions (RRCs) are a common response to sustained esophageal distension among spastic achalasia patients when evaluated with the functional luminal imaging probe. We evaluated patients with postfundoplication dysphagia, i.e., patients with suspected mechanical obstruction, and found that RRCs occasionally occurred among postfundoplication patients, but often in association with manometric features of esophageal neuromuscular imbalance. Thus, RRCs appear to be a manifestation of spastic esophageal dysmotility, likely from neural imbalance resulting in excess excitation.

Achalasia: It Is Not All Black and White

PURPOSE OF REVIEW

This review aims to shed light on subtleties of achalasia diagnosis, including potential pitfalls that may lead to errors. Optimal methods for assessment of disease severity and the relationship between achalasia and other motility disorders will also be reviewed with an emphasis on recent findings from the literature.

RECENT FINDINGS

Adjunctive testing with viscous substances or larger water volumes should be used routinely as it improves the accuracy of achalasia diagnosis. Chronic opiate use can mimic achalasia. The timed barium swallow remains the best test for assessments of disease severity and prognostication, but the functional lumen-imaging probe, a newer tool which measures esophagogastric junction distensibility using impedance planimetry, is emerging as a potentially more powerful tool for these purposes. Functional esophagogastric junction outflow obstruction is possibly part of the achalasia spectrum. By addressing the potential pitfalls described, and through routine and standardized use of the diagnostic tools mentioned herein, the accuracy of diagnosis, severity assessment, and prognostication of achalasia can be improved.

Manometric Subtypes of Ineffective Esophageal Motility

Objectives:

Ineffective esophageal motility (IEM) is characterized by well-defined manometric criteria. However, much variation exists within the diagnosis: Some patients exhibit exactly the required five weak swallows to make the diagnosis. Others show consistently ineffective swallows with total absence of any normal swallow. “We hypothesize” there are two different manometric subtypes of IEM; IEM Alternans (IEM-A) and IEM Persistens (IEM-P).

Methods:

A total of 231 IEM patients were identified by high-resolution manometry (HRM). IEM defined by distal contractile integral (DCI) <450 mm Hg/s/cm in ≥50% of test swallows. Abnormal reflux study was defined by excess total number of reflux episodes, abnormal esophageal acid exposure, or positive symptom association.

Results:

A total of 195 (84%) patients had IEM-A and 36 (16%) had IEM-P. A striking gender difference with 34% of IEM-A being males compared to 53% of IEM-P. (P=0.03). Mean age of IEM-P (59.6 years+/−13.1) was greater than IEM-A (55.5 years+/−13.6) (P=0.04). Mean lower esophageal sphincter (LES) resting pressure was significantly lower in IEM-P (20.8 mm Hg+/−1.4) than IEM-A (29 mm Hg+/−1.2) (P=0.002). There was no difference in LES-integrated relaxation pressure (IRP), bolus transit, or manometric presence of hiatal hernia between the two groups. Out of 146, 89 (61%) patients had abnormal reflux study. Esophageal acid exposure in upright position was significantly higher in IEM-P than IEM-A (3.5 vs. 1.7%, P=0.04). Poor gastric acid control on proton pump inhibitor (PPI) was more prevalent among IEM-P patients (58%) than IEM-A (27%) (P=0.007). In subgroup analysis of 41 IEM patients with dysphagia, DCI for liquid swallows was significantly lower in IEM-P (111+/−142 mm Hg/s/cm) compared to IEM-A (421+/−502 mm Hg/s/cm) (P=0.04), lower mean LES resting pressure in IEM-P (16.6+/−9 mm Hg) than IEM-A (31.7+/−18 mm Hg) (P=0.01).

Conclusions:

There are two distinct manometric IEM subtypes; IEM-P with an older male predominance, more advanced reflux disease, weaker LES, and worse response to PPI; likely a more advanced manifestation than IEM-A. However, the question if there are different etiologies underlying the two subtypes remains to be answered.

Evaluation of Esophageal Motility Utilizing the Functional Lumen Imaging Probe

OBJECTIVES

Esophagogastric junction (EGJ) distensibility and distension-mediated peristalsis can be assessed with the functional lumen imaging probe (FLIP) during a sedated upper endoscopy. We aimed to describe esophageal motility assessment using FLIP topography in patients presenting with dysphagia.

METHODS

In all, 145 patients (aged 18-85 years, 54% female) with dysphagia that completed upper endoscopy with a 16-cm FLIP assembly and high-resolution manometry (HRM) were included. HRM was analyzed according to the Chicago Classification of esophageal motility disorders; major esophageal motility disorders were considered "abnormal". FLIP studies were analyzed using a customized program to calculate the EGJ-distensibility index (DI) and generate FLIP topography plots to identify esophageal contractility patterns. FLIP topography was considered "abnormal" if EGJ-DI was <2.8 mm²/mm Hg or contractility pattern demonstrated absent contractility or repetitive, retrograde contractions.

RESULTS

HRM was abnormal in 111 (77%) patients: 70 achalasia (19 type I, 39 type II, and 12 type III), 38 EGJ outflow obstruction, and three jackhammer esophagus. FLIP topography was abnormal in 106 (95%) of these patients, including all 70 achalasia patients. HRM was "normal" in 34 (23%) patients: five ineffective esophageal motility and 29 normal motility. In all, 17 (50%) had abnormal FLIP topography including 13 (37%) with abnormal EGJ-DI.

CONCLUSIONS

FLIP topography provides a well-tolerated method for esophageal motility assessment (especially to identify achalasia) at the time of upper endoscopy. FLIP topography findings that are discordant with HRM may indicate otherwise undetected abnormalities of esophageal function, thus FLIP provides an alternative and complementary method to HRM for evaluation of non-obstructive dysphagia.

Lymphocytic Esophagitis in Nonachalasia Primary Esophageal Motility Disorders: Improved Criteria, Prevalence, Strength of Association, and Natural History

Lymphocytic esophagitis (LE) is a histologic pattern with no established clinical correlates in the majority of patients. The goal of this study was to evaluate the association between nonachalasia primary esophageal motility disorders (PEMD) and LE. Sixty-nine patients with PEMD and esophageal biopsies, including 22 with nutcracker esophagus, 33 with ineffective motility, and 14 with diffuse spasm, constituted the study group. The control group consisted of 70 patients with severe dysmotility-negative gastroesophageal reflux disease requiring referral for Nissen fundoplication. To improve the criteria for LE, a lymphocyte reference range at different esophageal levels was first established in 17 healthy volunteers. The cutoffs for normal intraepithelial lymphocytes, defined as lymphocyte levels not exceeding mean level±2 SDs, were set at 62, 46, and 41 lymphocytes per high-power field at 0 to 2, 5, and 10 cm above the gastroesophageal junction, respectively. Predominantly focal peripapillary LE was observed in approximately 40% of patients with nutcracker esophagus or diffuse spasm and in 20% of patients with ineffective motility, in comparison with 4% of patients with dysmotility-negative gastroesophageal reflux disease (P<0.035 vs. any subtype of PEMD). Overall, LE was strongly associated with PEMD in multivariate analysis (adjusted odds ratio, 7.93; 95% confidence interval, 2.26-27.9; P=0.001). LE had a chronic course in 56% of the patients with follow-up biopsies. In conclusion, LE has a strong association with PEMD, suggesting the utility of LE in raising the possibility of PEMD.

Lymphocytic Esophagitis With CD4 T-cell-predominant Intraepithelial Lymphocytes and Primary Esophageal Motility Abnormalities: A Potential Novel Clinicopathologic Entity

Lymphocytic esophagitis (LE) is an uncommon poorly defined histologic pattern. Its significance is largely unknown. The goal of our study was to characterize LE clinically, histologically, and immunophenotypically. Biopsies of 45 patients with LE and no intraepithelial granulocytes were selected throughout a 36-month period during routine diagnostic work. After reevaluation, complete absence of intraepithelial granulocytes was confirmed in 21 patients (LE-NG group), and few granulocytes were found in 24 patients (LE-FG). The control group consisted of 28 patients with active esophagitis consistent with reflux and overtly increased intraepithelial lymphocytes (REIL). The ratio of CD4:CD8 intraepithelial lymphocytes (IEL)>1 indicated predominance of CD4 IEL; the ratio ≤1 indicated predominance of CD8 IEL. Dysphagia was the primary complaint in 71%, 54%, and 39% of the patients with LE-NG, LE-FG, and REIL, respectively (P=0.04, LE-NG vs. REIL). Importantly, primary esophageal motility abnormalities were found in 10/11 (91%) tested LE-NG patients, 6/10 (60%) LE-FG patients, and 6/11 (54%) REIL patients. CD4 IELs were predominant in 81%, 50%, and 39% of LE-NG, LE-FG, and REIL cases, respectively (P=0.004, LE-NG vs. REIL), and in 90%, 83%, and 88% of the cases with primary motility abnormalities from the same groups. The prevalence of primary motility abnormalities was significantly higher in patients with CD4-predominant esophagitis than in patients with CD8-predominant esophagitis from all groups (21/24 [83%] vs. 2/8 [25%], P=0.005). A distinctive type of LE with predominance of CD4 IEL is associated with primary motility abnormalities suggesting a diagnostic utility of evaluating CD4 and CD8 subpopulations of T cells in LE.

Novel investigational drugs for constipation-predominant irritable bowel syndrome: a review

INTRODUCTION

Constipation-predominant irritable bowel syndrome (IBS-C) is a functional gastrointestinal (GI) disorder with an unknown etiology. A number of the drugs tested for IBS-C have also been applied to chronic constipation and chronic idiopathic constipation. Unfortunately, due to severe adverse effects, many drugs envisioned for IBS-C had been withdrawn from the market. Nevertheless, a number of potential new agents for this indication are now under development.

AREAS COVERED

The following review describes the most recently developed agents in preclinical as well as Phase 1 and Phase 2 clinical studies. Information was obtained from published literature, abstracts and the latest results found in Clinicaltrial.gov database. The authors put a special interest on glucagon-like peptide 1 analogue, bile acid modulators, serotonergic agents, guanylate cyclase C and cannabinoid antagonists.

EXPERT OPINION

To enter the market, a newly-developed drug has to meet several criteria, such as good bioavailability or the absence of drug-related adverse events. Taking into account constipation and abdominal pain as the main symptoms in IBS-C, a novel successful drug is usually able to improve both at the same time. Four out of fifteen investigational drugs described in this paper belong to the serotonergic family and have a good prognosis to reach the market; still, more long-term clinical studies are warranted.

Esophageal hypomotility and spastic motor disorders: current diagnosis and treatment

Esophageal hypomotility (EH) is characterized by abnormal esophageal peristalsis, either from a reduction or absence of contractions, whereas spastic motor disorders (SMD) are characterized by an increase in the vigor and/or propagation velocity of esophageal body contractions. Their pathophysiology is not clearly known. The reduced excitation of the smooth muscle contraction mediated by cholinergic neurons and the impairment of inhibitory ganglion neuronal function mediated by nitric oxide are likely mechanisms of the peristaltic abnormalities seen in EH and SMD, respectively. Dysphagia and chest pain are the most frequent clinical manifestations for both of these dysfunctions, and gastroesophageal reflux disease (GERD) is commonly associated with these motor disorders. The introduction of high-resolution manometry (HRM) and esophageal pressure topography (EPT) has significantly enhanced the ability to diagnose EH and SMD. Novel EPT metrics in particular the development of the Chicago Classification of esophageal motor disorders has enabled improved characterization of these abnormalities. The first step in the management of EH and SMD is to treat GERD, especially when esophageal testing shows pathologic reflux. Smooth muscle relaxants (nitrates, calcium channel blockers, 5-phosphodiesterase inhibitors) and pain modulators may be useful in the management of dysphagia or pain in SMD. Endoscopic Botox injection and pneumatic dilation are the second-line therapies. Extended myotomy of the esophageal body or peroral endoscopic myotomy (POEM) may be considered in highly selected cases but lack evidence.

Nutcracker esophagus: demographic, clinical features, and esophageal tests in 115 patients

Nutcracker esophagus (NE) is a common esophageal motility disorder chacterized by high amplitude peristaltic contractions in the distal esophagus. While previous studies have examined selected aspects of this condition (e.g. pathogenesis and treatment), there is a paucity of data regarding demographic and clinical features in large cohorts of patients. The aim of this study was to describe demographics, clinical features, comorbidities, time to diagnosis, source of patient referral by specialty, and medication use in a large cohort of patients with NE. We retrospectively analyzed consecutive cases of NE diagnosed from 2008-2010. The electronic medical records of these patients were reviewed, and relevant information was extracted. We identified 115 patients with NE. The median age was 62 years (range 25-87 years), and 63% were female. The median time patients experienced symptoms prior to diagnosis was 24 months (0-480 months). Most patients presented to an internal medicine consultant (42%) or to a gastroenterologist (35%). Presenting symptoms were chest pain (31%) and dysphagia (21%). Gastroesophageal reflux disease (GERD) symptoms were common: heartburn occurred in 51% of patients, 77% had a prior history of GERD, and 78% were receiving acid suppressive medications. GERD was confirmed by testing in at least 35%. Psychiatric comorbidity occurred in 24% with half the patients receiving psychotropic medications. Irritable bowel syndrome (IBS) and fibromyalgia co-existed in 15% and 12% of patients, respectively. Surprisingly, opioids were prescribed to 26% of patients. No statistically significant correlation was found between esophageal motility parameters and symptoms. In this study, NE patients were more commonly middle-aged females experiencing a considerable amount of time between symptom onset and diagnosis. Many were initially evaluated by internists for dysphagia or chest pain and had a history of GERD. Medication prescribed prior to diagnoses frequently involved acid suppression, but narcotic and psychotropic prescriptions were also commonly used. Central sensitization syndromes (fibromyalgia and IBS), psychiatric comorbidity, and reflux commonly coexisted. Our study suggests that future investigations should address the role and interaction of GERD and psychiatric disorders in NE.

Esophageal function testing: beyond manometry and impedance

Manometry and impedance provide only surrogate information regarding longitudinal wall function and are focused on contractile amplitude and lumen content. Ultrasound imaging provides a unique perspective of esophageal function by providing important information regarding longitudinal muscle contraction. Laser Doppler assessment of perfusion may be an important complementary tool to assess abnormal wall blood perfusion as a possible mechanism of pain.

Inflammatory responses in the muscle coat of stomach and small bowel in the postoperative ileus model of guinea pig

PURPOSE

Small intestinal function returns first after surgery, and then the function of the stomach returns to normal after postoperative ileus (POI). The aim of this study was to investigate inflammatory responses in the muscle coat of stomach and small intestine in guinea pig POI model.

MATERIALS AND METHODS

The distance of charcoal migration from pylorus to the distal intestine was measured. Hematoxylin and eosin (H&E) and immunohistochemical stain for calprotectin were done from the histologic sections of stomach, jejunum and ileum obtained at 3 and 6 hour after operation. Data were compared between sham operation and POI groups.

RESULTS

The distance of charcoal migration was significantly reduced in the 3 and 6 hour POI groups compared with sham operated groups (p<0.05). On H&E staining, the degree of inflammation was significantly higher in the stomach of 3 hour POI groups compared with jejunum and ileum of POI groups or sham operated groups (p<0.05). Calprotectin positive cells were significantly increased in the muscle coat of stomach of 3 hour POI groups compared with jejunum and ileum of POI groups or sham operated groups (p<0.05). There was strong association between the degree of inflammation and calprotectin positive cells in stomach.

CONCLUSION

Postoperative ileus induced by cecal manipulation significantly increased the degree of inflammation and calprotectin positive cells in the muscle coat of stomach as a remote organ. The relevance of degree of inflammation and the recovery time of ileus should be pursued in the future research.

The spectrum of achalasia: lessons from studies of pathophysiology and high-resolution manometry

High-resolution manometry and recently described analysis algorithms, summarized in the Chicago Classification, have increased the recognition of achalasia. It has become apparent that the cardinal feature of achalasia, impaired lower esophageal sphincter relaxation, can occur in several disease phenotypes: without peristalsis, with premature (spastic) distal esophageal contractions, with panesophageal pressurization, or with peristalsis. Any of these phenotypes could indicate achalasia; however, without a disease-specific biomarker, no manometric pattern is absolutely specific. Laboratory studies indicate that achalasia is an autoimmune disease in which esophageal myenteric neurons are attacked in a cell-mediated and antibody-mediated immune response against an uncertain antigen. This autoimmune response could be related to infection of genetically predisposed subjects with herpes simplex virus 1, although there is substantial heterogeneity among patients. At one end of the spectrum is complete aganglionosis in patients with end-stage or fulminant disease. At the opposite extreme is type III (spastic) achalasia, which has no demonstrated neuronal loss but only impaired inhibitory postganglionic neuron function; it is often associated with accentuated contractility and could be mediated by cytokine-induced alterations in gene expression. Distinct from these extremes is progressive plexopathy, which likely arises from achalasia with preserved peristalsis and then develops into type II achalasia and then type I achalasia. Variations in its extent and rate of progression are likely related to the intensity of the cytotoxic T-cell assault on the myenteric plexus. Moving forward, we need to integrate the knowledge we have gained into treatment paradigms that are specific for individual phenotypes of achalasia and away from the one-size-fits-all approach.

Longitudinal muscle of the esophagus: its role in esophageal health and disease

PURPOSE OF REVIEW

The muscularis propria of the esophagus is organized into circular and longitudinal muscle layers. The function of the longitudinal muscle and its role in bolus propulsion are not clear. The goal of this review is to summarize what is known of the role of the longitudinal muscle in health, as well as in sensory and motor disorders of the esophagus.

RECENT FINDINGS

Simultaneous manometry and ultrasound imaging reveal that, during peristalsis, the two muscle layers of the esophagus contract in perfect synchrony. On the contrary, during transient lower esophageal sphincter (LES) relaxation, longitudinal muscle contracts independent of the circular muscle. Recent studies have provided novel insights into the role of the longitudinal muscle in LES relaxation and descending relaxation of the esophagus. In certain diseases (e.g. some motility disorders of the esophagus), there is discoordination between the two muscle layers, which likely plays an important role in the genesis of dysphagia and delayed esophageal emptying. There is close temporal correlation between prolonged contractions of the longitudinal muscles of the esophagus and esophageal 'angina-like' pain. Novel techniques to record longitudinal muscle contraction are reviewed.

SUMMARY

Longitudinal muscles of the esophagus play a key role in the physiology and pathophysiology of esophageal sensory and motor function. Neuro-pharmacologic controls of circular and longitudinal muscle are different, which provides an opportunity for the development of novel pharmacological therapies in the treatment of esophageal sensory and motor disorders.

The effects of prucalopride on postoperative ileus in guinea pigs

PURPOSE

Postoperative ileus (POI) is an impairment of coordinated gastrointestinal (GI) motility that develops as a consequence of abdominal surgery and is a major factor contributing to patient morbidity and prolonged hospitalization. The aim of this study was to investigate the effects of different 5-hydroxytryptamine 4 (5-HT₄) receptor agonists, which stimulate excitatory pathways, on a POI model.

MATERIALS AND METHODS

The experimental model of POI in guinea pigs was created by laparotomy, gentle manipulation of the cecum for 60 seconds, and closure by suture, all under anesthesia. Different degrees of restoration of GI transit were measured by the migration of charcoal. Colonic transit was indirectly assessed via measurement of fecal pellet output every hour for 5 hours after administration of various doses of mosapride, tegaserod, prucalopride, and 5-HT.

RESULTS

Charcoal transit assay showed that various 5-HT₄ receptor agonists can accelerate delayed upper GI transit in a dose-dependent manner. However, fecal pellet output assay suggested that only prucalopride had a significant effect in accelerating colonic motility in POI.

CONCLUSION

Although mosapride, tegaserod, and prucalopride produce beneficial effects to hasten upper GI transit in the POI model, prucalopride administered orally restores lower GI transit as well as upper GI transit after operation in a conscious guinea pig. This drug may serve as a useful candidate for examination in a clinical trial for POI.

Longitudinal muscle dysfunction in achalasia esophagus and its relevance

Muscularis propria of the esophagus is organized into circular and longitudinal muscle layers. Goal of this review is to summarize the role of longitudinal muscle in physiology and pathophysiology of esophageal sensory and motor function. Simultaneous manometry and ultrasound imaging that measure circular and longitudinal muscle contraction respectively reveal that during peristalsis 2 layers of the esophagus contract in perfect synchrony. On the other hand, during transient relaxation of the lower esophageal sphincter (LES), longitudinal muscle contracts independently of circular muscle. Recent studies provide novel insights, i.e., longitudinal muscle contraction of the esophagus induces LES relaxation and possibly descending relaxation of the esophagus. In achalasia esophagus and other motility disorders there is discoordination between the 2 muscle layers. Longitudinal muscle contraction patterns are different in the recently described three types of achalasia identified by high-resolution manometry. Robust contraction of the longitudinal muscle in type II achalasia causes pan-esophageal pressurization and is the mechanism of whatever little esophageal emptying that take place in the absence of peristalsis and impaired LES relaxation. It may be that preserved longitudinal muscle contraction is also the reason for superior outcome to medical/surgical therapy in type II achalasia esophagus. Prolonged contractions of longitudinal muscles of the esophagus is a possible mechanism of heartburn and "angina like" pain seen in esophageal motility disorders and possibly achalasia esophagus. Novel techniques to record longitudinal muscle contraction are on the horizon. Neuro-pharmacologic control of circular and longitudinal muscles is different, which provides an important opportunity for the development of novel pharmacological therapies to treat sensory and motor disorders of the esophagus.

Neural plasticity in the gastrointestinal tract: chronic inflammation, neurotrophic signals, and hypersensitivity

Neural plasticity is not only the adaptive response of the central nervous system to learning, structural damage or sensory deprivation, but also an increasingly recognized common feature of the gastrointestinal (GI) nervous system during pathological states. Indeed, nearly all chronic GI disorders exhibit a disease-stage-dependent, structural and functional neuroplasticity. At structural level, GI neuroplasticity usually comprises local tissue hyperinnervation (neural sprouting, neural, and ganglionic hypertrophy) next to hypoinnervated areas, a switch in the neurochemical (neurotransmitter/neuropeptide) code toward preferential expression of neuropeptides which are frequently present in nociceptive neurons (e.g., substance P/SP, calcitonin-gene-related-peptide/CGRP) and of ion channels (TRPV1, TRPA1, PAR2), and concomitant activation of peripheral neural glia. The functional counterpart of these structural alterations is altered neuronal electric activity, leading to organ dysfunction (e.g., impaired motility and secretion), together with reduced sensory thresholds, resulting in hypersensitivity and pain. The present review underlines that neural plasticity in all GI organs, starting from esophagus, stomach, small and large intestine to liver, gallbladder, and pancreas, actually exhibits common phenotypes and mechanisms. Careful appraisal of these GI neuroplastic alterations reveals that--no matter which etiology, i.e., inflammatory, infectious, neoplastic/malignant, or degenerative--neural plasticity in the GI tract primarily occurs in the presence of chronic tissue- and neuro-inflammation. It seems that studying the abundant trophic and activating signals which are generated during this neuro-immune-crosstalk represents the key to understand the remarkable neuroplasticity of the GI tract.

Weak and absent peristalsis

BACKGROUND

Weak and absent esophageal peristalsis are frequently encountered esophageal motility disorders, which may be associated with dysphagia and which may contribute to gastroesophageal reflux disease. Recently, rapid developments in the diagnostic armamentarium have taken place, in particular, in high-resolution manometry with or without concurrent intraluminal impedance monitoring.

PURPOSE

This article aims to review the current insights in the terminology, pathology, pathophysiology, clinical manifestations, diagnostic work-up,and management of weak and absent peristalsis.

Pharmacologic specificity of nicotinic receptor-mediated relaxation of muscarinic receptor precontracted human gastric clasp and sling muscle fibers within the gastroesophageal junction

Relaxation of gastric clasp and sling muscle fibers is involved the transient lower esophageal sphincter relaxations underlying the pathophysiology of gastroesophageal reflux disease (GERD). These fibers do not contribute tone to the high-pressure zone in GERD patients, indicating their role in pathophysiology. This study identifies some mediators of the nicotine-induced relaxation of muscarinic receptor precontracted gastric clasp and sling fibers. Muscle strips from organ donors precontracted with bethanechol were relaxed with nicotine and then rechallenged after washing and adding inhibitors tetrodotoxin (TTX), the nitric-oxide synthase inhibitor L-nitro-arginine methyl ester (L-NAME), the β-adrenoceptor antagonist propranolol, the glycine receptor antagonist strychnine or ginkgolide B, and the GABA(A) receptor antagonist bicuculline or 2-(3-carboxypropyl)-3-amino-6-(4 methoxyphenyl)pyridazinium bromide [(gabazine) SR95531]. TTX only inhibited clasp fiber relaxations. L-NAME and propranolol inhibited, and ginkgolide B was ineffective in both. SR95531 was ineffective in clasp fibers and partially effective in sling fibers. Strychnine and bicuculline prevented relaxations with low potency, indicating actions not on glycine or GABA(A) receptors but more consistent with nicotinic receptor blockade. Bethanechol-precontracted fibers were relaxed by the nitric oxide donor S-nitroso-N-acetyl-DL-penicillamine and by the β-adrenergic agonist isoproterenol (clasp fibers only) but not by the glycine receptor agonist taurine or glycine or the GABA(A) agonist muscimol. These data indicate that nicotinic receptor activation mediates relaxation via release of nitric oxide in clasp and sling fibers, norepinephrine acting on β-adrenoceptors in clasp fibers, and GABA acting on GABA(A) receptors in sling fibers. Agents that selectively prevent these relaxations may be useful in the treatment of GERD.

New-generation 5-HT4 receptor agonists: potential for treatment of gastrointestinal motility disorders

IMPORTANCE OF THE FIELD

Gastrointestinal (GI) dysmotility is an important mechanism in functional GI disorders (FGIDs) including constipation, irritable bowel syndrome, functional dyspepsia, and gastroparesis. 5-hydroxytryptamine(4) (5-HT(4)) receptors are targets for the treatment of GI motility disorders. However, older 5-HT(4) receptor agonists had limited clinical success because they were associated with changes in the function of the cardiac HERG potassium channel.

AREAS COVERED IN THIS REVIEW

We conducted a PubMed search using the following key words alone or in combination: 5-HT(4), safety, toxicity, pharmacokinetics, pharmacodynamics, clinical trial, cardiac, hERG, arrhythmia, potassium current, elderly, prucalopride, ATI-7505, and velusetrag (TD-5108), to review mechanisms of action, clinical efficacy, safety and tolerability of three new-generation 5-HT(4) receptor agonists.

WHAT THE READER WILL GAIN

Prucalopride, ATI-7505, and velusetrag (TD-5108) are highly selective, high-affinity 5-HT(4) receptor agonists that are devoid of action on other receptors within their therapeutic range. Their efficacy has been demonstrated in pharmacodynamic studies which demonstrate acceleration of colonic transit and, to a variable degree, in clinical trials that significantly relieve chronic constipation. Currently available evidence shows that the new 5-HT(4) receptor agonists have safe cardiac profiles.

TAKE HOME MESSAGE

New-generation 5-HT(4) receptor agonists and future drugs targeting organ-specific splice variants are promising approaches to treat GI dysmotility, particularly colonic diseases.

Endoscopic evaluation of gastric emptying and effect of mosapride citrate on gastric emptying

PURPOSE

Gastric emptying has been evaluated by scintigraphy in spite of its limitations of time consumption, cost, and danger of radioisotope. Endoscopy is a simple technique, however, its validation for gastric emptying and quantification of food has not yet been investigated. The aim of our study was to assess endoscopic gastric emptying compared with scintigraphy and radiopaque markers (ROMs) studies. We also investigated the effect of a single dose of mosapride on gastric emptying.

MATERIALS AND METHODS

Fifteen healthy volunteers underwent scintigraphy. Next day, subjects received a standard solid meal with ROMs and underwent endoscopy and simple abdomen X-ray after 3 hrs. After one week, the same procedure was repeated after ingestion of mosapride (5 mg for group 1, n = 8; 10 mg for group 2, n = 7) 15 min before the meal. Quantification of gastric residue by endoscopy was scored from 0 to 3, and the scores were added up.

RESULTS

All subjects completed the study without any complication. The gastric emptying rate [T(1/2) (min)] was in normal range (65.6 +/- 12.6 min). Endoscopic gastric emptying was correlated significantly with gastric clearance of ROMs (r = 0.627, p = 0.012). Endoscopic gastric emptying and gastric clearance of ROMs after administration of mosapride showed significant differences in the 10 mg group (p < 0.05).

CONCLUSION

Endoscopy can evaluate gastric emptying safely and simply on an outpatient basis. A 10 mg dose of mosapride enhanced gastric emptying, assessed by both endoscopy and ROMs.

Multiple rapid swallowing: a complementary test during standard oesophageal manometry

Multiple rapid swallowing (MRS) stimulates neural inhibition resulting in abolition of contractions in the oesophageal body (OB) and complete lower oesophageal sphincter (LOS) relaxation which is followed by peristalsis and LOS contraction. The aim of this study was to evaluate the yield of MRS to detect abnormalities in inhibitory or excitatory oesophageal mechanisms in patients with oesophageal symptoms and either normal standard manometry or ineffective oesophageal motility (IOM). MRS (five water swallows, 2 mL, separated by 2-3 s) was evaluated in 23 healthy subjects, 109 symptomatic patients with normal standard sleeve manometry and in 48 patients with IOM. Healthy subjects had complete inhibition of OB motility during MRS and a strong motor response after MRS, i.e. amplitude of OB contractions in the oesophageal body and LOS tone being higher than after single swallows. Almost 70% of patients with oesophageal symptoms and normal manometry had abnormal MRS, mainly consistent on inability to increase amplitude of OB contractions after MRS. Nearly, half of the patients with IOM were able to normalize OB contractions after MRS. MRS is a simple complementary test that can be added to standard oesophageal manometry. Two-thirds of patients with normal manometry show abnormal MRS that could potentially underlie their symptoms. A normal response to MRS in patients with severe IOM might be used to predict response to prokinetic treatment.

The neural regulation of the mammalian esophageal motility and its implication for esophageal diseases

In contrast to the tunica muscularis of the stomach, small intestine and large intestine, the external muscle layer of the mammalian esophagus contains not only smooth muscle but also striated muscle fibers. Although the swallowing pattern generator initiates the peristaltic movement via vagal preganglionic neurons that project to the myenteric ganglia in the smooth muscle esophagus, the progressing front of contraction is organized by a local reflex circuit composed by intrinsic neurons similarly to other gastrointestinal tracts. On the other hand, the peristalsis of the striated muscle esophagus is both initiated and organized by the swallowing pattern generator via vagal motor neurons that directly innervate the muscle fibers. The presence of a distinct ganglionated myenteric plexus in the striated muscle portion of the esophagus had been enigmatic and neglected in terms of peristaltic control for a long time. Recently, the regulatory roles of intrinsic neurons in the esophageal striated muscle have been clarified. It was reported that esophageal striated muscle receives dual innervation from both vagal motor fibers originating in the brainstem and varicose intrinsic nerve fibers originating in the myenteric plexus, which is called 'enteric co-innervation' of esophageal motor endplates. Moreover, a putative local neural reflex pathway that can control the motility of the striated muscle was identified in the rodent esophagus. This reflex circuit consists of primary afferent neurons and myenteric neurons, which can modulate the release of neurotransmitters from vagal motor neurons in the striated muscle esophagus. The pathogenesis of some esophageal disorders such as achalasia and gastroesophageal reflux disease might be involved in dysfunction of the neural networks including alterations of the myenteric neurons. These evidences indicate the physiological and pathological significance of intrinsic nervous system in the regulation of the esophageal motility. In addition, it is assumed that the components of intrinsic neurons might be therapeutic targets for several esophageal diseases.