What Causes GERD?
Gastroesophageal reflux (GER) occurs when a circular band of smooth muscles at the junction of the esophagus and stomach, called the lower esophageal sphincter (LES), temporarily relaxes, allowing acidic stomach contents to come up and potentially damage the esophagus. (1) This process is called a transient lower esophageal relaxation (TLESR).
Though regarded as the chief cause of GERD, transient lower esophageal sphincter relaxations are as mentioned before, a normal physiological process in the human body. These relaxations occur multiple times a day whenever we swallow food or burp and is imperative for the stomach to vent gas and induce vomiting. A study found that GERD patients and healthy individuals without GERD experience a similar number of lower esophageal sphincter relaxations. (2)
TLESRs appear to become an issue only when there is an abnormally high frequency of relaxations or if there is an inability to clear acidic stomach contents from the throat. Numerous studies strongly implicate the significance of saliva and diaphragmatic breathing in clearing the throat of acid and relieving GERD symptoms. (1) (3).
Another cause of GER is a hypotensive or an incompetent LES. A hypotensive or incompetent LES stays open longer than usual due to a lack of gastric pressure, which increases the likelihood of acid reflux. In healthy individuals, LES pressure is maintained in the stomach at 10-30 mm Hg to keep it from relaxing. A person with a hypotensive LES has a lower than normal gastric pressure, usually less than 10 mm Hg. A person with an incompetent LES has an even lower gastric pressure at less than 4 mm Hg. (2)
Only a minority of patients have a hypotensive or incompetent LES. (4) This condition is more common in patients with erosive esophagitis than in patients with non-erosive esophagitis. Hiatal hernias are also known to decrease LES pressure and contribute to acid reflux. (2)
The most common medication used to diagnose and treat GERD are proton pump inhibitors (PPIs) like Prilosec and Nexium. Proton pump inhibitors (PPIs) work by limiting the ability of proton pumps within stomach cells to produce acid, thereby reducing esophageal exposure to acid. (5) For patients suspected of GERD, a physician will usually evaluate the patient with a questionnaire and prescribe 4-8 weeks of PPI medication treatment to test for GERD (6). If reflux symptoms do not improve or get worse, GERD may be ruled out. If symptoms diminish or disappear during PPI therapy and no alarm symptoms such as bleeding or diarrhea occur, a diagnosis of GERD is usually given.
There are also several tests that a physician can perform to diagnose GERD or confirm the diagnosis of GERD. All tests involve passing a tubular scope through either the nose or mouth to look at the vocal cords and esophagus.
Conventional Laryngoscopy: A diagnosis of GERD is usually determined by how a patient responds to acid reducing medication, but if laryngopharyngeal reflux is suspected, your physician may conduct a laryngoscopy. A laryngoscopy is a procedure in which a thin tubular scope with a camera and light at the end is inserted through the mouth down to the larynx for a visual inspection of the vocal cords and surrounding tissue.
Modern, high volume ENT centers will most likely perform this procedure with a thinner, less invasive flexible, fiberoptic scope (Transnasal Flexible Laryngoscopy) inserted through the nose, rather than the traditional 90-degree rigid scope. A physician will check the vocal cords and glottis for signs of irritation and growths. (7)
Though laryngoscopy technology has evolved considerably through the years, the effectiveness of the procedure remains uncertain. Studies have shown that laryngoscopy findings are the same between normal individuals and extra-esophageal reflux sufferers. (8) Laryngeal irritation appears to be very common even in healthy non-smokers without GERD. One study found laryngeal irritation in over 83 to 93% of their healthy non-smoking subjects with no history of GERD. (9)
Endoscopy: An endoscopy is similar to a laryngoscopy except a longer and sometimes thicker scope is used to evaluate not only the larynx but the entire esophageal tract and stomach. The scope with a camera and light is usually inserted through the mouth and is performed under sedation. The camera on the scope projects images on a computer screen and allows the doctor to examine the lower esophageal sphincter muscle for abnormalities and growths.
A small blade is generally attached to the end of the scope to sample tissue and check for abnormalities. Newer high tech endoscopes called transnasal endoscopes are inserted through the nose and do not require sedation. They are generally more comfortable and less invasive than standard endoscopes that are inserted through the mouth and do require sedation. Endoscopies are commonly done in serious cases, such as GERD that is unresponsive to medication.
An endoscopy is useful and important for identifying serious GERD complications such as erosive esophagitis, peptic strictures, Barrett’s Esophagus, and cancer. (10) (11) (12). Some physicians may also choose to “scope” a patient who does not respond to PPI therapy (deemed refractory GERD). Though endoscopies remain one of the most common ways for a doctor to diagnose GERD, research has shown that upper endoscopies are often overused on low-risk GERD patients without much benefit. (13) Financial incentives may be a factor in endoscopic overuse.
Ambulatory Esophageal pH Monitoring: If a patient with extraesophageal GERD is unresponsive to acid reflux medication, physicians may conduct an ambulatory pH monitoring test to find out why. (14) Ambulatory pH monitoring is the current gold standard used to detect and confirm abnormal esophageal acid reflux. (13) The traditional procedure is performed with a thin flexible tubular sensor that is inserted through the nose and passed down to the lower esophagus, right above the lower esophageal sphincter to determine acidity levels. (1) Patients on acid reflux medication will be instructed to get off of them for seven days before the procedure to ensure the accuracy of pH levels findings. (1)
The idea is to see how if your pH levels are abnormal when you are off PPIs. The pH scope is connected to a small computer clipped to the patient’s side. The scope is left inside the patient to record reflux episodes for 24 hours. A pH monitoring device typically measures 6 different factors:
1. The total duration of acid exposure
2. Duration of acid exposure when upright
3. Duration of acid exposure when lying down
4. The number of reflux episodes
5. The number of reflux episodes lasting longer than 5 minutes
6. The duration of the longest reflux episode (1)
Physicians with newer medical equipment may use a wireless pH monitoring device with the ability to detect the direction of acid reflux as well non-acid reflux. (13) A pH monitoring device is planted in the stomach by suction and can be left in patients for up to 96 hours. Data is collected and transmitted to a computer attached to the patient’s belt. When data collection is complete, the device is expelled through the digestive tract. (5)
Though considered by some as an effective gold standard for detecting acid reflux, several studies have questioned the test for its inability to detect non-acid reflux and for its lack of sensitivity in patients with extraesophageal GERD symptoms. (8) (9) (14) (15)
One study that implemented pH monitoring found only 54% of their patients with suspected LPR tested positive for abnormal esophageal reflux exposure. (9) 46% of patients with LPR tested negative for abnormal pH results. Another study even showed up to 43% of healthy subjects with no LPR had abnormal hypopharyngeal pH readings. (9) Though pH monitoring can suggest a diagnosis of GERD in patients unresponsive to medication, it does not seem reliable to make medical decisions. (7)