Widespread endoscopic mucosal resection of the esophagus with strategies for stricture prevention: a preclinical study

BACKGROUND AND STUDY AIMS

Circumferential endoscopic mucosal resection of the esophagus is complicated by stricture formation. Prophylactic measures for avoiding such strictures have not been well studied. The aim of this preclinical study was to assess strategies for prevention of esophageal strictures in a porcine model following widespread endoscopic mucosal resection (EMR).

METHODS

A total of 18 60-kg pigs were included in the study. The roles of strip width (group 1), prophylactic steroids (group 2), and prophylactic stents (group 3) in the prevention of post-mucosectomy strictures were studied. Six animals were included in each group. Esophageal mucosal resection was achieved using a novel widespread EMR technique previously described by our group. Animals in group 1 underwent partial (50% circumference) mucosal resection without prophylactic measures, while animals in the other two groups underwent circumferential mucosal resection. Animals in group 2 received 80 mg of triamcinolone injected directly into the exposed submucosal tissue (20 mg injection in four quadrants). Animals in group 3 received esophageal metal stents coated with small-intestine submucosa (SIS) that were deployed immediately post-resection. Animals were kept alive for 1 month.

RESULTS

Partial and circumferential widespread EMRs were achieved in all animals. There were no procedural complications. Repeat endoscopy at 1 month showed no strictures in group 1. Only four animals were studied in group 2, owing to the high complication rate (periesophageal abscess in all animals) with one early death. Three of the surviving animals developed mild to tight strictures. In group 3, all animals developed tight strictures; however, there was early stent migration in four animals and premature stent removal in two animals because of persistent vomiting.

CONCLUSIONS

Partial widespread EMR of the esophagus heals without stricture formation and does not require prophylactic intervention. The use of deep mural steroid injection following a circumferential resection does not appear to prevent strictures and may result in serious adverse events. Short-term use of esophageal stents is inadequate for stricture prevention. However, better results may be anticipated with longer term (at least 6 weeks) stent use.

Effects of botulinum toxin A on the sphincter of Oddi: an in vivo and in vitro study

BACKGROUND

Botulinum toxin A is a potent inhibitor of the release of acetylcholine from nerve endings. Local injection of botulinum toxin has recently been suggested to be helpful in sphincter of Oddi dyskinesia by decreasing sphincter of Oddi pressure.

AIMS

To explore the mechanism of action of botulinum toxin A on sphincter of Oddi (SO) muscle.

METHODS

Four piglets underwent duodenoscopy and SO manometry was performed. After obtaining a baseline pressure, the SO was injected with normal saline and the experiment repeated after one week. The SO was then injected endoscopically with botulinum toxin (40 U) with follow up manometry one week later. The sphincter of Oddi was removed from 10 pigs, cut into three rings, and placed in an organ bath. The force of contraction was measured and registered on a polygraph. Rings were stimulated by 70 V (10 Hz, 0.5 ms) electrical field stimulation for 20 seconds, exogenous acetylcholine (100 microM), and KCl (125 mM). Botulinum toxin (0.1 U/ml) or atropine (1 microM) was added to the incubation medium and the stimulation was repeated.

RESULTS

Mean basal SO pressure in the pigs remained unchanged after saline injection but decreased to about 50% of baseline value following botulinum toxin injection (p = 0.04). The contractions induced by direct stimulation of SO smooth muscle with KCl were not significantly affected by either atropine or botulinum toxin. In all rings exogenous acetylcholine induced contractions, which were totally blocked by atropine, but not by botulinum toxin. Electrical field stimulation induced contractions that were inhibited by both atropine and botulinum toxin.

CONCLUSION

Botulinum toxin inhibits pig sphincter of Oddi smooth muscle contractions by a presynaptic cholinergic mechanism, similar to that described in skeletal muscle.

Carcinoma oesophagus--an unusual cause of hypertrophic osteoarthropathy

A rare case of Hypertrophic Osteoarthropathy in association with carcinoma of the oesophagus has been reported from Indian subcontinent. In addition to long bones short tubular bones are also involved in our case. Neurogenic theory is the most feasible pathogenesis for hypertrophic osteoarthropathy in the present case.

Clinical and roentgenological profiles and etiological correlations of encysted pleural effusions

One hundred and thirty-six cases of encysted pleural effusions were studied and investigated to reach an etiological diagnosis. The clinical profile of encysted pleural effusions differed little from that of free pleural effusions. Of the four sites of encystments seen (costoparietal, interlobar, subpulmonic, and mediastinal), costoparietal effusions were the commonest and resulted most often from infections. Interlobar encystments came next in frequency and most often resulted from congestive cardiac failure. Of the various causes of encysted pleural effusions, tuberculosis was the commonest, followed by pyogenic infection and congestive cardiac failure, in this order. Conventional radiographic techniques were adequate in diagnosing most cases of encysted pleural effusions.