Oesophageal motor functions and its disorders

The perilous consequences of bowel preparation: a case study with literature review of Boerhaave syndrome

Colonoscopy is widely acknowledged as a prevalent and efficacious approach for the diagnosis and treatment of gastrointestinal disorders. In order to guarantee an effective colonoscopy, it is imperative for patients to undergo an optimal bowel preparation regimen. This entails the consumption of a substantial volume of a non-absorbable solution to comprehensively purge the colon of any fecal residue. Nevertheless, it is noteworthy to acknowledge that the bowel preparation procedure may occasionally elicit adverse symptoms such as nausea and vomiting. In exceptional instances, the occurrence of excessive vomiting may lead to the rupture of the distal esophagus, a grave medical condition referred to as Boerhaave syndrome (BS). Timely identification and efficient intervention are imperative for the management of this infrequent yet potentially perilous ailment. This investigation presents a case study of a patient who developed BS subsequent to the ingestion of mannitol during bowel preparation. Furthermore, an exhaustive examination of extant case reports and pertinent literature on esophageal perforation linked to colonoscopy has been conducted. This analysis provides valuable insights into the prevention, reduction, and treatment of such serious complications.

Changes in specific esophageal neuromechanical wall states are associated with conscious awareness of a solid swallowed bolus in healthy subjects

Esophageal neuromechanical wall states are the physical manifestations of circular muscle inhibition and contraction resulting from neural inputs and leading to bolus propulsion. A novel method infers esophageal neuromechanical wall states through simultaneous determination of pressure and diameter in vivo using impedance manometry. We hypothesized that changes in esophageal neuromechanical wall states relate to conscious awareness of esophageal bolus passage ("bolus perception"). Seven healthy participants were selected for perception of solid bolus passage and were compared with seven healthy participants with no conscious awareness of solid bolus passage. Participants were studied using impedance manometry (MMS Solar, Unisensor, 20 Hz). Subjects swallowed ten 5-ml liquid and ten 2-cm square saline-soaked bread boluses and rated bolus perception using a visual analog scale. Esophageal neuromechanical wall states were calculated and analyzed. Proportions of time spent in states with and without luminal distension were compared using a two-proportions Z-test. Bolus perception was associated with neuromechanical wall states corresponding to luminal distension more frequently than matching states without distension in the proximal esophagus (P < 0.001) and transition zone (P < 0.001), whereas there were no differences for the distal esophagus. In healthy volunteers, perceived swallows relate to changes in esophageal neuromechanical wall states in the proximal esophagus. We postulate that these changes relate to bolus retention and summation of active and passive wall tension activating intramural tension receptors.NEW & NOTEWORTHY This study explores esophageal neuromechanical wall states derived from changes in pressure and impedance-derived distension in relation to conscious awareness of esophageal solid bolus transit in healthy volunteers. There are increases in neuromechanical wall states indicative of esophageal distension in healthy volunteers with conscious awareness of bolus transit as compared with unaware individuals. Bolus-based esophageal distension is postulated as a mechanism for esophageal symptoms such as dysphagia.

Sildenafil improves clinical signs and radiographic features in dogs with congenital idiopathic megaoesophagus: a randomised controlled trial

We evaluated the efficacy of oral sildenafil citrate in dogs with congenital idiopathic megaoesophagus (CIM). Twenty-one puppies were randomly assigned to two groups (treatment and control). The dogs were given sildenafil oral suspension 1 mg/kg every 12 hours for 14 days or placebo in a masked fashion. Clinical signs (frequency of regurgitation and weight gain) and oesophagrams (relative oesophageal diameter, ROD) were evaluated in order to assess the efficacy of drug treatment, by examiners who were unaware of the study protocol. In addition, a set of in vitro experiments on isolated samples of canine lower oesophageal sphincter (LOS) was performed, and the effects of increasing concentrations of sildenafil on basal tone and electrically-stimulated motility were assessed. Sildenafil administration significantly reduced the number of regurgitation episodes (0.88±1.40 v 2.65±1.56, P<0.0001) and significantly increased weight gain in the treated dogs compared to controls (79.76±28.30 per cent v 53.40±19.30 per cent, P=0.034). ROD values, at the end of the treatment period, were significantly decreased in the sildenafil group, compared to pre-treatment values (0.97±0.19 v 0.24±0.14, P<0.0001), in contrast to control subjects (0.98±0.17 v 1.10±0.25, P=0.480). In accordance with the in vivo findings, sildenafil dose-dependently reduced basal tone and increased electrically-induced relaxation of dog LOS samples. These results suggest that sildenafil citrate helps ameliorate clinical and radiographic signs in dogs with CIM by reducing LOS tone, and could represent a novel therapeutic tool for the treatment of this disease.

Clinical, endoscopic and manometric features of the primary motor disorders of the esophagus

BACKGROUND

Significant incidence, diagnostic difficulties, clinical relevance and therapeutic efficacy associated with the small number of publications on the primary esophageal motor disorders, motivated the present study.

AIM

To determine the manometric prevalence of these disorders and correlate them to the endoscopic and clinical findings.

METHODS

A retrospective study of 2614 patients, being 1529 (58.49%) women and 1085 (41.51%) men. From 299 manometric examinations diagnosed with primary esophageal motor disorder, were sought-clinical data (heartburn, regurgitation, dysphagia, odynophagia, non-cardiac chest pain, pharyngeal globe and extra-esophageal symptoms) and/or endoscopic (hiatal hernia, erosive esophagitis, food waste) that motivated the performance of manometry.

RESULTS

Were found 49 cases of achalasia, 73 diffuse spasm, 89 nutcracker esophagus, 82 ineffective esophageal motility, and six lower esophageal sphincter hypertension. In relation to the correlations, it was observed that in 119 patients clinical conditions were associated with dysphagia, found in achalasia more than in other conditions; in relationship between endoscopic findings and clinical conditions there was no statistical significance between data.

CONCLUSION

The clinical and endoscopic findings have little value in the characterization of the primary motor disorders of the esophagus, showing even more the need for manometry, particularly in the preoperative period of gastroesophageal reflux disease.

Excitatory and inhibitory enteric innervation of horse lower esophageal sphincter

The lower esophageal sphincter (LES) is a specialized, thickened muscle region with a high resting tone mediated by myogenic and neurogenic mechanisms. During swallowing or belching, the LES undergoes strong inhibitory innervation. In the horse, the LES seems to be organized as a "one-way" structure, enabling only the oral-anal progression of food. We characterized the esophageal and gastric pericardial inhibitory and excitatory intramural neurons immunoreactive (IR) for the enzymes neuronal nitric oxide synthase (nNOS) and choline acetyltransferase. Large percentages of myenteric plexus (MP) and submucosal (SMP) plexus nNOS-IR neurons were observed in the esophagus (72 ± 9 and 69 ± 8 %, respectively) and stomach (57 ± 17 and 45 ± 3 %, respectively). In the esophagus, cholinergic MP and SMP neurons were 29 ± 14 and 65 ± 24 vs. 36 ± 8 and 38 ± 20 % in the stomach, respectively. The high percentage of nitrergic inhibitory motor neurons observed in the caudal esophagus reinforces the role of the enteric nervous system in the horse LES relaxation. These findings might allow an evaluation of whether selective groups of enteric neurons are involved in horse neurological disorders such as megaesophagus, equine dysautonomia, and white lethal foal syndrome.

Upper gastrointestinal motility: prenatal development and problems in infancy

Deglutition, or swallowing, refers to the process of propulsion of a food bolus from the mouth into the stomach and involves the highly coordinated interplay of swallowing and breathing. At 34 weeks gestational age most neonates are capable of successful oral feeding if born at this time; however, the maturation of respiration is still in progress at this stage. Infants can experience congenital and developmental pharyngeal and/or gastrointestinal motility disorders, which might manifest clinically as gastro-oesophageal reflux (GER) symptoms, feeding difficulties and/or refusal, choking episodes and airway changes secondary to micro or overt aspiration. These problems might lead to impaired nutritional intake and failure to thrive. These gastrointestinal motility disorders are mostly classified according to the phase of swallowing in which they occur, that is, the oral preparatory, oral, pharyngeal and oesophageal phases. GER is a common phenomenon in infancy and is referred to as GERD when it causes troublesome complications. GER is predominantly caused by transient relaxation of the lower oesophageal sphincter. In oesophageal atresia, oesophageal motility disorders develop in almost all patients after surgery; however, a congenital origin of disordered motility has also been proposed. This Review highlights the prenatal development of upper gastrointestinal motility and describes the most common motility disorders that occur in early infancy.

Postnatal changes in vagal control of esophageal muscle contractions in rats

AIMS

Replacement of smooth muscles by striated muscles occurs in the esophagus during the early postnatal period. The aim of this study was to clarify postnatal changes in vagal control of esophageal muscle contractions in rats.

MAIN METHODS

An isolated segment of the neonatal rat esophagus was placed in an organ bath and the contractile responses were recorded using a force transducer.

KEY FINDINGS

Electrical stimulation of the vagus trunk evoked a biphasic contractile response in the neonatal esophageal segment. The first and second components of the contractions were inhibited by α-bungarotoxin and atropine, respectively. Ganglion blockers, hexamethonium and mecamylamine, did not affect vagally mediated contractions. The first component gradually enlarged with age in days, whereas the second component declined during the first week after birth. Application of d-tubocurarine or acetylcholine caused an apparent contraction in the esophageal striated muscle at postnatal day 0, but responses to these drugs were not observed at 1 week after birth. The neonatal esophagus expressed the γ-subunit of nicotinic acetylcholine receptors. In contrast, the ε-subunit was dominantly expressed in the adult esophagus.

SIGNIFICANCE

The vagus nerves directly innervate both the esophageal striated muscles and smooth muscles in the early neonatal period. During the process of muscle rearrangement, the property of the striated muscles is altered substantially. The specific features of striated muscles in the neonatal rat esophagus might compensate for immature formation of neuromuscular junctions. Unsuccessful conversion of the striated muscle property during postnatal muscle rearrangement would be related to disorders of esophageal motility.

Altered GI motility in critically Ill patients: current understanding of pathophysiology, clinical impact, and diagnostic approach

Gastrointestinal (GI) motility disturbances are common in critically ill patients. GI tract dysmotility has been linked to increased permeability of intestinal mucosa and bacterial translocation, contributing to systemic inflammatory response syndrome, sepsis, and multiple organ dysfunction syndrome. A key issue in providing nutrition to critically ill patients is intolerance of enteral feeding as a result of impaired GI motility. Remarkable progress has been made in the understanding of the regulation of GI motility in critical illness. Predominant motility abnormalities seen in ICU patients include antral hypomotility, delayed gastric emptying, and reduced migrating motor complexes. The diagnosis of motility disturbances can be challenging to establish in critically ill patients. The available tests used for detection of abnormal motility have major limitations in the ICU setting. Recognition of the type and site of intestinal motility disorder is important to guide the therapy and improve the outcome.

The impact of automatic retractors on the esophagus during anterior cervical surgery: an experimental in vivo study in a sheep model

Object

Postoperative dysphagia is a well-recognized complication of the anterior surgical approach to the cervical spine. However, its incidence and etiology remain unknown. The aim of this study was to investigate the impact of automatic retractor use on the esophagus and to describe the related pathological changes that might occur during cervical spine surgery.

Methods

A single-level cervical discectomy was performed via an anterior approach in 16 skeletally mature female sheep. Continuous retraction was applied with an automatic retractor system during surgery. The sheep model was chosen because of anatomical similarities to the human esophagus. The esophageal tract in every animal was examined using contrast radiographic examination. Eight animals were killed 3 days after the operation (Group 1). The remaining sheep were killed 4 weeks after the operation (Group 2). The esophagi were removed for histopathological study, which was performed using H & E and Masson trichrome staining. The changes in esophageal innervation were examined with nicotinamide adenine dinucleotide diphosphate–diaphorase histochemical staining.

Results

Only 1 animal (a Group 1 sheep) demonstrated any postoperative radiographic abnormality. In Group 1 sheep, histopathological study of the esophagi at the treated level revealed edema between the muscular fibers in the outer longitudinal and inner circular layers of the muscularis propria. At some points, obvious signs of vascular congestion, vascular damage, and inflammation were observed. In the Group 2 animals, there was mild-to-moderate fibrosis extending from the outer surface of the esophagus to the longitudinal layers of the muscularis propria in the area to which retraction had been applied. Enzyme-histochemical staining revealed the presence of normal myenteric plexus and ganglion cells, and nitrergic innervation in all parts of the esophagus wall.

Conclusions

The results of this study demonstrate that direct pressure induced by the medial retractor blade on the esophagus wall leads to local injury. Postoperative dysphagia in human patients who have undergone anterior cervical spine surgery could be a clinical manifestation of this phenomenon.

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.

Axial force measurement for esophageal function testing

The esophagus serves to transport food and fluid from the pharynx to the stomach. Manometry has been the “golden standard” for the diagnosis of esophageal motility diseases for many decades. Hence, esophageal function is normally evaluated by means of manometry even though it reflects the squeeze force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe with combined axial force and manometry recordings showed that axial force amplitude increased by 130% in contrast to an increase of 30% using manometry. Using axial force in combination with manometry provides a more complete picture of esophageal motility, and the current paper outlines the advantages of using this method.

Is all ineffective esophageal motility the same? A clinical and high-frequency intraluminal US study

BACKGROUND

Ineffective esophageal motility (IEM) is characterized by frequent hypotensive or failed peristaltic contractions; its pathophysiology is controversial.

OBJECTIVE

To evaluate whether patients with IEM because of GERD would differ from patients with other etiologies of IEM on the basis of esophageal-muscle thickness measured by high-frequency intraluminal US (HFIUS).

DESIGN

Single-center prospective study.

SETTING

Academic medical center; from January 2004 to June 2005.

SUBJECTS

A total of 46 patients who were newly diagnosed with IEM were classified into 2 groups: GERD-related IEM (group I, n = 26) and non-GERD-related IEM (group II, n = 20) on the basis of the presence of reflux esophagitis and/or pathologic acid exposure by 24-hour esophageal pH monitoring. In addition, 16 asymptomatic healthy volunteers with no reflux esophagitis, normal manometric finding, and normal level of acid exposure were included as controls.

MAIN OUTCOME MEASUREMENTS

We compared the clinical characteristics, including a predominant principal esophageal symptom and the results from HFIUS among the control, GERD-related IEM (group I), and non-GERD-related IEM (group II) groups.

RESULTS

The proportion of typical reflux symptom as a predominant symptom was higher in group I (66%) than in group II (25%). Muscle thickness was greater in group II than in group I and the control group during both the baseline rest period and the peak of contraction period at all levels of the middle of the lower esophageal sphincter (LES), and 3 cm and 9 cm above the LES (respectively) (P < .05).

LIMITATION

The limitation was the small sample size.

CONCLUSIONS

Patients with non-GERD-related IEM had increased muscle thickness on HFIUS compared with patients with GERD-related IEM and the controls. Based on this study, IEM is not necessarily indicative of GERD.

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

The pathogenesis of nutcracker oesophagus (NE) and ineffective oesophageal motility (IEM) is unclear. Damage to the enteric nervous system or smooth muscle can cause oesophageal dysmotility. We tested the hypothesis that NE and IEM are associated with abnormal muscular or neural constituents of the oesophageal wall. Oesophageal manometry was performed in patients prior to total gastrectomy for gastric cancer. The oesophageal manometries were categorized as normal (n = 7), NE (n = 13), or IEM (n = 5). Histologic examination of oesophageal tissue obtained during surgery was performed after haematoxylin and eosin (H&E) and trichrome staining. Oesophageal innervation was examined after immunostaining for protein gene product-9.5 (PGP-9.5), choline acetyltransferase (ChAT) and neuronal nitric oxide synthase (nNOS). There were no significant differences in inner circular smooth muscle thickness or degree of fibrosis among the three groups. Severe muscle fibre loss was found in four of five patients with IEM. The density of PGP-9.5-reactive neural structures was not different among the three groups. The density of ChAT immunostaining in the myenteric plexus (MP) was significantly greater in patients with NE (P < 0.05) and the density of nNOS immunostaining in the circular muscle (CM) was significantly greater in IEM patients (P < 0.05). The ChAT/nNOS ratio in both MP and CM was significantly greater in NE patients. NE may result from an imbalance between the excitatory and inhibitory innervation of the oesophagus, because more than normal numbers of ChAT-positive myenteric neurones are seen in NE. Myopathy and/or increased number of nNOS neurones may contribute to the hypocontractile motor activity of IEM.

Is Esophageal Dysmotility after Laparoscopic Adjustable Gastric Banding Reversible?

Laparoscopic adjustable gastric banding (LAGB) has become an increasingly popular option to treat morbid obesity. Esophageal dysmotility secondary to LAGB has been described, but is usually reversible after removal of the band. Long-term esophageal dysmotility persisting after removal of the band is an unusual and not yet described complication. We report the case of a 58-year-old obese patient who developed severe dysphagia and vomiting associated with atypical esophageal dysmotility 22 months after gastric band placement. Radiological exploration revealed no acute band slippage but only a pseudoachalasia. Device deflation and then band removal were required in an attempt to treat her symptoms. Esophageal dysmotility persisted for several months after band removal and was still present after a Roux-en-Y gastric bypass performed as revisional operation. Possible mechanisms generating this complication and clinical implications are discussed.

Prevalence of increased esophageal muscle thickness in patients with esophageal symptoms

BACKGROUND

Patients with achalasia, diffuse esophageal spasm (DES), and nutcracker esophagus have a thicker muscularis propria than normal subjects. The goal of our study was to determine the prevalence of increased muscle thickness in a group of unselected patients referred to the esophageal function laboratory for evaluation of the symptoms.

METHODS

We studied 40 normal subjects and 94 consecutive patients. Manometry and ultrasound images were recorded concurrently, using a special custom-built catheter. Esophageal muscle thickness and muscle cross-sectional area were measured at 2 and 10 cm above the lower esophageal sphincter (LES). Patients were assigned manometric diagnosis and determination was made if they had increased muscle thickness and muscle cross-sectional area.

RESULTS

Nearly all patients with well-defined spastic motor disorders, i.e., achalasia, DES, and nutcracker esophagus, revealed (a) an increase in the muscle thickness/cross-sectional area, (b) increase in esophageal muscle thickness/cross-sectional area was also seen, albeit at a lower prevalence rate, in patients with less well-characterized manometric abnormalities, i.e., hypertensive LES, impaired LES relaxation, and ineffective esophageal motility, and (c) 24% of patients with esophageal symptoms but normal manometry were also found to have an increase in muscle thickness/cross-sectional area. Dysphagia was more likely, and heartburn less likely in patients with increased muscle thickness, but there were no differences in chest pain and regurgitation symptoms between the groups.

CONCLUSION

We describe, for the first time, increased muscle thickness in patients with esophageal symptoms and normal manometry. We suggest that increased esophageal muscle thickness is likely to be an important marker of esophageal motor dysfunction.

Intestinal motility disturbances in intensive care patients pathogenesis and clinical impact

BACKGROUND

Gastrointestinal motility disturbances in critically ill patients are frequent in the ICU setting, causing considerable discomfort and are associated with increased rates of morbidity and mortality. This review focuses on the pathophysiological basis of intestinal motility, the major patterns of pathological motility alterations, the impact on patient outcome, and current therapeutic options.

DISCUSSION

Intestinal motility is controlled by the enteric nervous system, modulated by hormones and extrinsic afferent and efferent neurons. Pathological motility disturbances can affect the stomach, small bowel, and colon separately or in combination. Changes in esophageal motor activity contribute to the aspiration of gastric juice, whereas early enteral feeding most frequently fails due to gastric intolerance. Disturbances in digestive and interdigestive motility patterns and the inability to switch motor activity from the interdigestive to the digestive pattern also contribute to feeding disability and thus to increased morbidity and mortality as well.

CONCLUSIONS

The therapeutic options for motility disturbances in critically ill patients include the adjustment of electrolyte imbalances, tailored fluid management, early enteral feeding, appropriate management of catecholamines and drugs used for analgosedation, and prokinetic drugs. Unfortunately, the therapeutic options for treating motility disturbances in ICU patients are still limited. This situation requires careful assessment of ICU patients with respect to gut motility disturbances and their pathophysiological mechanisms and an individually tailored treatment to prevent further aggravation of existing motility disturbances.

Primary esophageal motility disorders: Concise review for clinicians

Primary esophageal motility disorders comprise various abnormal manometric patterns which usually present with dysphagia or chest pain. Some, such as achalasia, are diseases with a well defined pathology, characteristic manometric features, and good response to treatments directed towards the palliation of symptoms. Other disorders, such as diffuse esophageal spasm and nutcracker esophagus, have no well defined pathology and could represent a range of motility abnormalities associated with subtle neuropathic changes, gastresophageal reflux and anxiety states. On the other hand, hypocontracting esophagus is generally caused by weak musculature commonly associated with gastresophageal reflux disease. Although manometric patterns have been defined for these disorders, the relation with symptoms is poorly defined and in some cases the response to medical or surgical therapy unpredictable. The aim of this paper is to present a wide spectrum of the primary esophageal motility disorders, as well as to give a concise review for the clinicians encountering these specific diseases. .