Sergio E. Fuentealba

Sacral nerve stimulation induces pan-colonic propagating pressure waves and increases defecation frequency in patients with slow-transit constipation.

Objective  Colonic propagating sequences are important for normal colonic transit and defecation. The frequency of these motor patterns is reduced in slow‐transit constipation. Sacral nerve stimulation (SNS) is a useful treatment for faedcal and urinary incontinence. A high proportion of these patients have also reported altered bowel function. The effects of SNS on colonic propagating sequences in constipation are unknown. Our aims were to evaluate the effect of SNS on colonic pressure patterns and evaluate its therapeutic potential in severe constipation.

Pancolonic spatiotemporal mapping reveals regional deficiencies in, and disorganization of colonic propagating pressure waves in severe constipation

Background  The morphology, motor responses and spatiotemporal organization among colonic propagating sequences (PS) have never been defined throughout the entire colon of patients with slow transit constipation (STC). Utilizing the technique of spatiotemporal mapping, we aimed to demonstrate ‘manometric signatures’ that may serve as biomarkers of the disorder.

Differential relaxation and contractile responses of the human upper esophageal sphincter mediated by interplay of mucosal and deep mechanoreceptor activation

BACKGROUND AND AIMS the neural mechanisms of distension-induced esophagoupper esophageal sphincter (UES) reflexes have not been explored in humans. We investigated the modulation of these reflexes by mucosal anesthesia, acid exposure, and GABA(B) receptor activation. In 55 healthy human subjects, UES responses to rapid esophageal air insufflation and slow balloon distension were examined before and after pretreatment with 15 ml of topical esophageal lidocaine, esophageal HCl infusion, and baclofen 40 mg given orally. In response to rapid esophageal distension, UES can variably relax or contract. Following a mucosal blockade by topical lidocaine, the likelihood of a UES relaxation response was reduced by 11% (P < 0.01) and the likelihood of a UES contractile response was increased by 14% (P < 0.001) without alteration in the overall UES response rate. The UES contractile response to rapid esophageal air insufflation was also increased by 8% (P < 0.05) following sensitization by prior mucosal acid exposure. The UES contractile response, elicited by balloon distension, was regionally dependent (P < 0.05) (more frequent and of higher amplitude with proximal esophageal distension), and the response was attenuated by topical lidocaine (P < 0.05). Baclofen (40 mg po) had no effect on these UES reflexes. Abrupt gaseous esophageal distension activates simultaneously both excitatory and inhibitory pathways to the UES. Partial blockade of the mucosal mechanosensitive receptors permits an enhanced UES contractile response mediated by deeper esophageal mechanoreceptors. Activation of acid-sensitive esophageal mucosal chemoreceptors upregulates the UES contractile response, suggestive of a protective mechanism.

Optimal criteria for detecting bolus passage across the pharyngo-oesophageal segment during the normal swallow using intraluminal impedance recording

Abstract  The impedance criteria for the detection of the arrival of bolus head and clearance of bolus tail in the pharynx have not been defined, and may differ from accepted criteria used in the oesophagus. Our aim was to define the optimal impedance criteria that most accurately defined passage of the swallowed bolus moving through the pharyngo‐oesophageal segment. In eight healthy volunteers, an assembly incorporating seven impedance‐measuring segments was positioned across the pharyngo‐oesophageal segment, and subjects swallowed liquid and semisolid radio‐opaque boluses (2–20 mL) while impedance was simultaneously recorded with videofluoroscopic images. To derive the optimal criteria, in an iterative process we correlated impedance defined bolus presence with fluoroscopy (Cohen’s Kappa) for a range of impedance cut‐off values from 100% to 0% for both the initial fall, and recovery of impedance. Bolus presence in the pharynx, as determined by the ‘standard’ criteria (50% drop and recovery to 50% of baseline), correlated very modestly with videofluoroscopy (κ≈0.35). The criteria that most accurately defined bolus passage varied between pharyngeal regions. Threshold (% of baseline) for bolus head entry into the region ranged from 71% to 80%. Threshold for bolus tail clearance varied from nadir to 19%. Correlation of impedance with videofluoroscopy improved to κ≈0.6 with the above criteria. The impedance criteria defining bolus presence across the pharyngo‐oesophageal segment differ from those adopted in the oesophagus. Pharyngeal impedance provides an accurate, non‐radiological indicator of bolus transit through the pharynx.

Factor analysis identifies subgroups of constipation

AIM To determine whether distinct symptom groupings exist in a constipated population and whether such grouping might correlate with quantifiable pathophysiological measures of colonic dysfunction. METHODS One hundred and ninety-one patients presenting to a Gastroenterology clinic with constipation and 32 constipated patients responding to a newspaper advertisement completed a 53-item, wide-ranging self-report questionnaire. One hundred of these patients had colonic transit measured scintigraphically. Factor analysis determined whether constipation-related symptoms grouped into distinct aspects of symptomatology. Cluster analysis was used to determine whether individual patients naturally group into distinct subtypes. RESULTS Cluster analysis yielded a 4 cluster solution with the presence or absence of pain and laxative unresponsiveness providing the main descriptors. Amongst all clusters there was a considerable proportion of patients with demonstrable delayed colon transit, irritable bowel syndrome positive criteria and regular stool frequency. The majority of patients with these characteristics also reported regular laxative use. CONCLUSION Factor analysis identified four constipation subgroups, based on severity and laxative unresponsiveness, in a constipated population. However, clear stratification into clinically identifiable groups remains imprecise.

Long-term outcome following pneumatic dilatation as initial therapy for idiopathic achalasia: an 18-year single-centre experience.

Relapse after treatment for idiopathic achalasia is common and long‐term outcome data are limited.

Acid sensitization of esophageal mucosal afferents: implication for symptom perception in patients across the gastroesophageal reflux disease spectrum.

Background:Sensitization of esophageal chemoreceptors, either directly by intermittent acid exposure or indirectly through esophagitis-associated inflammatory mediators, is likely to be the mechanism underlying the perception of heartburn. Aims:To compare basal esophageal sensitivity with electrical stimulation and acid, and to compare the degree of acid-induced sensitization in controls and in patient groups across the entire spectrum of gastroesophageal reflux disease: erosive oesophagitis (EO), nonerosive reflux disease (NERD), and functional heartburn (FH). Methods:Esophageal sensory and pain thresholds to electrical stimulation were measured before, 30, and 60 minutes after an intraesophageal infusion of saline or HCl. Patients received a 30-minute infusion of 0.15 M HCl and controls were randomized to receive either HCl (n=11) or saline (n=10). After electrical sensory threshold testing, participants received another 30-minute infusion of HCl to determine whether sensitivity to acid is increased by prior acid exposure Results:All patient groups had higher basal sensory thresholds than healthy controls (controls, 13±1.4 mA; FH, 20±5.1 mA; NERD, 21±5.1 mA; EO, 23±5.4 mA; P<0.05). Acute esophageal acid exposure reduced sensory thresholds to electrical stimulation in FH and NERD patients (P<0.05). The level of acid sensitivity during the first HCl infusion was comparable between all patient groups and controls. The secondary infusion caused increased discomfort in all participants (P<0.01). This acid-induced sensitization to HCl was significantly elevated in the patient groups ( P<0.05). Conclusions:(1) Esophageal acid infusion sensitizes it to subsequent electrical and chemical stimulation. (2) The acid-related sensitization is greater in gastroesophageal reflux disease than in controls and may influence in part symptom perception in this population. (3) Acid-related sensitization within the gastroesophageal reflux disease population is not dependant on mucosal inflammation.

Modulation of esophageal afferent pathways by 5‐HT3 receptor inhibition

Background  The study aims were to investigate whether neural pathways involving 5‐HT3 receptors mediate: (i) distension‐induced upper esophageal sphincter (UES) relaxation reflex, (ii) esophageal sensitivity to acid and electrical stimuli, and (iii) viserosomatic sensitization following acid exposure.

W1889 Long Term Outcome Following Pneumatic Dilatation for Idiopathic Achalasia

copist and uncomfortable for the patient, 3) the protracted and profound sedation frequently needed to perform the procedure increases the risk of aspiration and hypotension and 4) the use of an overtube increases the risk of esophageal perforation. We have developed a quick and simple technique of through-the-scope (TTS), wire-guided esophageal balloon dilation to treat EFI. Method: After initial endoscopic evaluation of the impacted food bolus, a TTS, wire-guided, 12mm balloon dilator is passed through the endoscope, and the guide wire is advanced gently through the bolus under direct endoscopic visualization. If the endoscopist encounters resistance or observes any bowing of the wire, the attempt is discontinued and the wire is redirected. When the wire is successfully advanced through the bolus and beyond the stenotic area, the uninflated balloon is passed over the wire into the stomach. The balloon is inflated within the stomach to its 12mm size, and then gently pulled back into the esophagus until resistance is encountered at the level of the stenosis. The balloon is then deflated, pulled back into the stenotic area, and reinflated to its 12 mm size. The balloon is finally deflated and removed, and the endoscope is used to gently push the bolus into the stomach. Results: We have treated 11 patients with this technique. Their mean age was 69.6 years (range 49-83 years) and all were men. All of the EFIs were caused by the ingestion of meat, and esophageal pathology was found in all 11 patients. Five patients (45%) had Schatzkis rings, 3 (27%) had benign esophageal strictures, and 3 (27%) had eosinophilic esophagitis. TTS, wire-guided esophageal balloon dilation successfully dislodged the EFI within 5 minutes in all 11 patients, and there were no major procedure related complications. Conclusions: TTS, wire-guided esophageal balloon dilation is a simple, quick and effective technique to treat EFI. We feel that this technique is less likely to result in complications than the conventional practice of endoscopic extraction using an overtube, but comparative studies are needed to establish the relative merits of these treatments.