The esophagus is a 25-30 centimeter long tube that food and liquids pass through, from the pharynx to the stomach.
The esophageal wall is made of 4 layers: the inner mucosa, which is made of stratified squamous epithelium, except at the lower esophageal sphincter, where it joins the gastric epithelium to form the gastroesophageal junction; the submucosa, a muscular layer; and an outer layer called adventitia.
At the top and bottom of the esophagus there are the upper and lower esophageal sphincters, respectively. Both relax during swallowing to allow the passing of food or liquids, propelled by peristaltic contractions.
Additionally, the lower esophageal sphincter is closed between meals to prevent acid reflux and has a resting pressure of 10 to 45 millimeters of mercury.
When the lower esophageal sphincter pressure is lower than normal, gastric acid reaches the esophagus and the pH of the esophagus drops from 7 to 4, and this is called acid reflux.
Some degree of acid reflux is normal, and it happens mostly after a meal, but it doesn’t cause esophageal damage or associated symptoms.
Gastroesophageal reflux disease, or GERD, happens when the resting pressure of the lower esophageal sphincter is below 10 millimeters of mercury, which allows the backflow of gastric acid in the esophagus, causing esophageal lesions and symptoms that mostly happen at night.
GERD can be caused by a hiatal hernia, where the stomach and lower part of the esophagus slide above the diaphragm and this usually happens in overweight, obese individuals. It can also occur during pregnancy due to increased pressure in the abdomen from the growing fetus.
Other common causes are products that increase the production of gastric acid or decrease the tone of the lower esophageal sphincter, like alcohol, spicy foods, caffeinated drinks including coffee, tea, and soda, citrus fruits, tomatoes, and even peppermint!
With GERD, typical symptoms include heartburn and regurgitation. But, GERD can also cause atypical symptoms such as retrosternal chest pain, dysphagia or difficulty swallowing, persistent coughing, voice changes, halitosis or bad breath, dental erosions, ear or nose discomfort, or even nocturnal asthma that is unresponsive to asthma therapy.
To help identify GERD as the cause of these atypical symptoms, a full workup can be done, which includes an upper endoscopy with biopsy, esophageal manometry, and 24-hour pH-monitoring.
Now, in addition, some individuals with GERD can have signs and symptoms that may be worrisome for an esophageal cancer. These include unintended weight loss, iron deficiency anemia, anorexia, odynophagia or painful swallowing, and upper gastrointestinal bleeding. In these situations, to help identify GERD, upper endoscopy and biopsy can be done.
Finally, in some individuals with risk factors for Barrett’s esophagus, which is a premalignant lesion, an upper endoscopy and biopsy may be done. These risk factors include male sex, white race, age over 50 years, obesity, tobacco use, having a hiatal hernia, and having a first degree relative with esophageal cancer.
An upper endoscopy with biopsy can detect various complications of GERD and it can rule out malignancy.
The most common complication is reflux esophagitis, and on upper endoscopy there are signs of erosion, even small ulcers. These lesions can be classified using the Los Angeles system or the Savary-Miller system, both of which use a 1 to 4 grading scale, where grade 1 is mild esophagitis and grade 4 is severe esophagitis.
A second complication is a peptic stricture, and on upper endoscopy there’s a narrowing of the lumen, most often in the distal esophagus. These peptic strictures form when esophageal erosions and ulcers heal and form fibrotic scars.
A third complication is Barrett’s esophagus, which is where metaplasia begins to develop. That’s where stratified squamous epithelium of the distal esophagus is replaced by metaplastic columnar epithelium. That’s the same cellular layer that’s found in the intestine and when it forms in the esophagus it becomes more likely to have cancer develop there. That’s why Barrett’s esophagus is considered a premalignant lesion.
In Barrett’s esophagus the upper endoscopy show a change in the epithelium that’s at least 1 centimeter above the gastroesophageal junction. A biopsy of that tissue confirms intestinal metaplasia, which is characterized by goblet cells that secrete mucus.
Over time, the metaplastic cells of Barrett’s esophagus start to undergo genetic changes and they become dysplastic. Meaning that the cells become bigger, pleomorphic, and being to proliferate quickly.
Based on the rate of proliferation, the tissue is categorized as low-grade dysplasia or high-grade dysplasia.
Biopsies typically show cytologic abnormalities like abnormally shaped cells with bigger nuclei that are undergoing atypical mitosis.
With adenocarcinoma, the tissue has already mutated to the point where proliferation is happening without regulation and the growing cell mass typically can break through normal tissue boundaries and invade neighboring tissues.
In individuals with atypical symptoms, and a normal upper endoscopy, esophageal manometry may be done next. This can help to identify functional esophageal disorders, such as achalasia and diffuse esophageal spasm, and evaluate the peristaltic function of the esophagus before a surgical intervention for GERD.
Manometry uses a pressure sensitive catheter that is inserted through the nose in the esophagus so it can measure the effectiveness of the peristaltic contractions, as well as the pressure in both upper and lower esophageal sphincters and with GERD, the pressure in the lower esophageal sphincter is below 10 millimeters of mercury, showing that the lower esophageal sphincter doesn’t close properly between meals and allows the backflow of gastric acid.
Ambulatory 24-hour esophageal pH monitoring is used to confirm the diagnosis of GERD in individuals with atypical symptoms or individuals that were unresponsive to medical therapy and still have symptoms. This is a minimally invasive technique in which a flexible catheter with a pH sensor is inserted through the nose and down into the distal esophagus. The outer part of the catheter is connected to a monitor on an individual’s belt.
After 24 hours, the data is analyzed and a Demeester score is calculated based on how many times the pH dropped below 4, the number of reflux episodes, and how long the longest reflux episode lasted. A score above 14.7 is suggestive of GERD.
Treatment of GERD starts with lifestyle and dietary changes that include weight loss in overweight and obese individuals. The goal is a Body Mass index between 18.5 to 25 kilograms per square meter.
In addition, it’s ideal have the head of the bed elevated at least 6 inches to prevent nocturnal GERD symptoms.
