Experimental Studies On The Change Of Esophageal Motility And The Mechanisms Of Visceral Hypersensitivity In Nonerosive Reflux Disease

Nonerosive reflux disease is defined as the presence of typical symptoms of gastroesophageal reflux disease(GERD) for more than 3 months in the absence of visible evidence of esophageal mucosal injure at endoscopy, which is an independent form of GERD. Over the past several decades, NERD had been thought to be a mild form of GERD and not to need therapy or only need lifestyle modification and therapy with H2 receptor antagonists. Now a great deal evidence has showed that NERD has a high prevalence rate, approximately accounting for 70% of GERD, and that the symptom pattern, severity of symptoms , complication and influence on patients's quality of life are similar to those in patients with RE, and the totle symptom improvement rate to the same antisecretory medication with the same dosage is lower than that of RE. The above conception that NERD is a mild form and needn't special therapy has been challenged. NERD represents an very important clinical problem and has been focused. Recent study found that the pathogenesis of NERD was complicated and acid was not the sole cause of the development of heartburn. It was also found that physiological amounts of acid reflux was enough to induce symptoms in some NERD patients with visceral sensory dysfunction, suggesting that visceral hypersensitivity may be involved in its development. The enhanced visceral sensitivity in NERD patients suggest neuro-fluid agent may be involved in it. It has been found spinal nerve is directly involved in mediating the transduction of the perception of discomfort and pain in esophagus. A large number of spinal nerve fibres are located in the totle layer of esophagus and their endings contain abundant substance P(SP) and calcitonin gene-related peptide(CGRP). It is known that SP plays an critically important role in the mechanism of the pathophysiology of irritable bowel disease. Whether SP is involved in the pathophysiology of NERD is still unknown. The purpose of this study was to explore the mechanism of visceral hypersensitivity in NERD by means of the measurement of esophgeal motility ,acid reflux pattern ,chemosensitivity and the investigation of neuropeptide immunoreactive fibres in the esophageal mucosa of this group of patients.1.Measure of esophageal motility in NERDThe aim of this part was to explore the change of esophageal motility in NERD . LES pressure was measured and the amplitude of peristaltic contractions of esophageal body were also measured at 18,13,8 and 3cm above LES in 36 patients with NERD, 15 with RE and 12 healthy subjects by means of manometry. The mean LES pressure in patients with NERD was significantly higher than that in patients with RE and was similar to that in HS; at 18cm above LES,there was no difference in the amplitude of peristaltic contractions among three groups; at 13,8 and 3cm above LES, the amplitude of esophageal contraction in NERD group was significantly higher than that in RE group and no difference was found between NERD group and HS. Our study show that patients with NERD have minor abnormalities in the function of LES and esophageal peristalsis and their antireflux barrier and acid clearance function are relatively intact and that the development of symptoms may ascribed to agents other than esophageal dysmotility.2.Esophageal 24h pH monitoring in NERD The aim of this part was to investigate the relation between acid reflux pattern and symptoms in NERD and thus to provide some experimental envidence for further study of the pathogenesis of NERD. Esophageal 24h pH monitoring was performed in 46 patients with NERD and 20 with RE. The result showed that patients with NERD were less likely to have an abnormal pH test than patients with RE; the mean number of acid reflux events and the time percentage when pH was under 4 at different postures were significantly lower in NERD group than those in RE group; there were no differences in the above indexs between NERD-positive(with an abnormal pH) and RE patients; in NERD-negative patients , the above indexs were significantly lower...