الفهرس 
ANATOMY OF THE ESOPHAGUSOnly 14 pages are availabe for public view
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Abstract
Barrett’s esophagus is a change in the distal esophageal epithelium of any length that can be recognized as columnar type mucosa at endoscopy and is confirmed to have intestinal metaplasia by biopsy of the tubular esophagus.
Frequency of BE in the general population have varied widely ranging from 0.9 to more than 20 percent depending in part upon the population studied and the definitions used, familial aggregation of Barrett’s esophagus has been described, the annual cancer incidence in patients with Barrett’s esophagus have ranged from 0.2 to 2.0 percent.
Risk factors considered by the AGA include; Age 50 years or older, male sex, White race, Chronic GERD, Hiatal hernia, Elevated body mass index and Intra-abdominal distribution of body fat.
Barrett’s esophagus develops through the process of metaplasia, in which one kind of fully differentiated (adult) cell replaces another, The pathogenesis of Barrett’s esophagus is now hypothesized to be a 2- step process; columnarization of the injured distal esophagus with cardiac mucosa followed by the formation of goblet cells or intestinal metaplasia.
Dysplasia and malignant transformation starts with genetic alterations that either activate protooncogenes, disable tumor suppressor genes, or both.
Three types of columnar epithelia have been described in Barrett’s esophagus, gastric fundic-type epithelium, cardia-type (also known as junctional-type) epithelium, intestinal-type epithelium (sometimes called specialized columnar epithelium or specialized intestinal metaplasia).
Barrett’s esophagus causes no symptoms. Most patients are seen initially for symptoms of associated GERD, such as burning pain arising from the epigastrium and radiating retrosternally to the throat and neck. Meals, recumbency, and bending over worsen the symptoms, whereas antacids, milk, and sitting or standing up relieve the symptoms.
Endoscopic examination is generally required to diagnose Barrett’s esophagus, two criteria must be fulfilled:
3- The endoscopist must document that columnar epithelium lines the distal esophagus.
4- Histologic examination of biopsy specimens from that columnar epithelium must reveal intestinal metaplasia
For endoscopic imaging of Barrett’s esophagus there are a number of advanced imaging techniques available, which are mainly used in experimental setting in tertiary centers, such as high resolution and magnification endoscopy, combination of acetic acid with magnification endoscopy is referred as enhanced magnification endoscopy.
Chromoendoscopy involves the use of stains or dyes during endoscopy to improve the visualization and characterization of the gastrointestinal mucosa, these stains includes lugol’s solution, methylene blue, indigo carmine, toluidine blue, congo red and phenol red.
Narrow band imaging (NBI) is a high-resolution endoscopic technique that enhances the fine structure of the mucosal surface without the use of dyes, autofluorescence imaging (AFI) which can potentially differentiate tissue types based on their difference in fluorescence emissions, Confocal laser endomicroscopy and endocytoscopy are emerging endoscopic technologies that permit high-resolution assessment of gastrointestinal mucosal histology at a cellular and sub-cellular level, OCT is similar in principle to ultrasonography but uses light waves rather than acoustical waves.
Other modalities as Raman spectroscopy, Elastic scatter spectroscopy, Wireless capsule endoscopy (WCE), endoscopic ultrasound, Computed tomography (CT) and positron emission tomography (PET).
The goal of a screening program should be to detect neoplasia or lesions at risk of developing neoplasia, allowing intervention or surveillance that leads to improved outcomes.
The management of patients with Barrett’s esophagus involves three major components:
7. Treatment of the associated GERD
8. Endoscopic surveillance to detect dysplasia
9. Treatment of dysplasia
In addition, chemoprevention to reduce the rate of malignant transformation.
Treatment of GERD include lifestyle modifications, medical treatment with PPI, surgical treatment with Nissen fundoplication either open or endoscopic, other techniques include Belsey Mark IV, Hill gastropexy, gastric bypass, endoscopic treatment include endoscopic mucosal suturing (Endocinch), application of radiofrequency energy to the distal esophagus (Stretta procedure), injection of a bulking agent into the wall of the distal esophagus (Enteryx and Gatekeeper) and Full-thickness plication of the gastro-esophageal junction.
Endoscopic surveillance for patients with BE is recommended to identify curable neoplasia.
Treatment of low grade dysplasia & non dysplastic BE with Endoscopic techniques for eradication of Barrett’s esophagus, including multipolar electrocoagulation, photodynamic therapy (PDT), and radiofrequency ablation (RFA), argon plasma coagulation (APC).
For patients with verified high-grade dysplasia (also called intraepithelial neoplasia) in Barrett’s esophagus, there are generally four proposed management options:
9. Esophagectomy
10. Endoscopic therapies that ablate the neoplastic tissue
11. Endoscopic mucosal resection
12. Intensive endoscopic surveillance in which invasive therapies are withheld until biopsy specimens reveal adenocarcinoma.
The American Gastroenterological Association (AGA) recommended that patients with high-grade dysplasia within Barrett’s esophagus undergo endoscopic eradication therapy with radiofrequency ablation, photodynamic therapy, or endoscopic mucosa resection. This recommendation varies from prior guidelines that suggested either esophagectomy or endoscopic therapies for the majority of patients with high-grade dysplasia.
Chemoprevention involves the use of a pharmacologic agent to prevent the development of cancer although a number of agents have been proposed for chemoprevention in Barrett’s esophagus; the most promising chemopreventive agents for this condition appear to be the proton pump inhibitors (PPIs) and the nonsteroidal anti-inflammatory drugs (NSAIDs).