Understanding Sphincter Dysfunction in GERD : Causes, Impact, and Treatment Options

Gastroesophageal reflux disease (GERD) is a health condition in which the stomach contents leak back into the food pipe or esophagus, which can irritate the food pipe and cause heartburn and various other symptoms.  There are two types of sphincters in the gastrointestinal tract, namely the upper esophageal sphincter (UES) and the lower esophageal sphincter (LES). The UES or the top sphincter prevents air from flowing into the food pipe or esophagus while breathing, and the LES, or the bottom sphincter prevents food from flowing backward to the esophagus. GERD is caused primarily due to LES dysfunction.⁽¹⁾

The lower esophageal sphincter (LES) includes a group of smooth muscles located at the base of the esophagus. These muscles open and allow food to flow into the stomach. Additionally, these muscles also help the esophagus initiate contractions due to which food moves downward and thus stops from flowing back up.

However, when this lower esophageal sphincter does not close properly, the contents from the stomach can leak back into the esophagus. This is known as reflux or gastroesophageal reflux. This can cause various symptoms, including heartburn. Harsh stomach acids can also damage the esophageal lining.

Risk factors for GERD can be aging, excessive body mass index (BMI), anxiety/depression, smoking, and reduced levels of physical activity.^{(2, 3, 4)} In addition to this, eating habits could also be a reason for GERD, including the acidity of food and the size and timing of meals. Recreational physical activity can prove to be protective in this regard.^{(4, 5)}

Although GERD is mainly a disorder of the lower esophageal sphincter, several other factors including physiological and pathological factors might contribute to its development. The most common cause is transient lower esophageal sphincter relaxations (TLESRs). These transient lower esophageal sphincter relaxations are brief movements of LES tone inhibition that are independent of a swallow.⁽⁶⁾ These are physiological factors contributing to GERD. Other factors, such as reduced lower esophageal sphincter (LES) pressure, impaired esophageal clearance, hiatal hernias, and delayed gastric emptying are also associated with GERD.⁽⁷⁾

GERD or acid reflux occurs when the lower esophageal sphincter does not close properly or when pressure from surrounding structures forces it to remain open. So, sphincter dysfunction has a large impact on acid reflux. There are several conditions when there is a sphincter dysfunction that can contribute to acid reflux. Some of these conditions include:

A condition in which the top of the stomach pushes up through the hole in the diaphragm where the food pipe or esophagus passes through is known as a hiatal hernia. This moves the lower esophageal sphincter (LES) above the diaphragm, where it loses some of its muscular support. These are extremely common, especially with aging.

Obesity increases the volume and pressure in the abdomen, which affects the lower esophageal sphincter. Obesity can weaken the muscles permanently as it tends to last longer. This can be a common contributing factor to developing a hiatal hernia.

Pregnancy can cause temporary acid reflux. The volume and pressure in the abdomen during pregnancy can push, stretch, and ultimately weaken the muscles in the diaphragm that support the lower esophageal sphincter. High levels of the hormone relaxin are secreted during pregnancy, which relaxes the muscles so that they can stretch enough to make room for the fetus. Pregnancy also brings high levels of hormones estrogen and progesterone, which may also relax the lower esophageal sphincter.

Smoking tobacco relaxes the lower esophageal sphincter (LES). It also triggers coughing, which opens the LES. Chronic coughing along with tobacco smoking can weaken the diaphragm muscles and cause the appearance of a hiatal hernia. Additionally, smoking also slows down digestion and leads to the production of more acid in the stomach.

Some other possible causes of lower esophageal sphincter dysfunction could be certain birth defects like esophageal atresia, and certain medications like Benzodiazepines, antidepressants, and NSAIDs that can have a relaxing effect on the lower esophageal sphincter.

Acid reflux could happen after a large or hefty meal, or when you lie down too early after dinner. The stomach acids rise into the food pipe, resulting in heartburn and other symptoms. Although occasional acid reflux can be manageable at home, chronic acid reflux or GERD (occurring primarily due to sphincter dysfunction) should be treated appropriately and as early as possible, because it can damage the esophagus tissues over time, if left untreated.

Below are some treatment options for sphincter dysfunction in gastroesophageal reflux disease (GERD).

Some commonly prescribed medications for lower esophageal sphincter dysfunction and GERD.

Prokinetic Agents: These medications enhance the motility of the gastrointestinal tract, including the lower esophageal sphincter and the esophagus. Prokinetic agents help in improving lower esophageal sphincter dysfunction and reduce episodes of acid reflux. Metoclopramide and cisapride are some examples of prokinetic agents.

Proton Pump Inhibitors (PPIs): These are potential acid-reducing medications and are often prescribed to manage symptoms of GERD and prevent complications linked with acid reflux. Some examples of PPIs are esomeprazole, omeprazole, pantoprazole, and rabeprazole.

Baclofen: It is a muscle relaxant and can be used off-label to reduce lower esophageal sphincter pressure and reduce reflux episodes. However, this medication comes with several side effects and thus should not be considered as a first level of treatment.

Antacids: Although antacids do not directly address lower esophageal sphincter dysfunction, they can be used for relieving some symptoms of GERD or acid reflux.

Nissen fundoplication and LINX devices are used as surgical interventions for treating lower esophageal sphincter dysfunction and GERD.

Nissen Fundoplication: This is the most common surgery for LES dysfunction and GERD. Here smaller incisions are made and the recovery time is quite less. The surgeon wraps the top of the stomach around the lower esophagus and secures it with stitches to tighten the junction between them.

LINX Devices: A newer surgical procedure for treating LES dysfunction implants a device called LINX during surgery. This device is a ring of tiny magnets that keeps the junction between the stomach and esophagus closed.

Sphincter dysfunction in GERD is quite common and this can cause the stomach contents to leak back into the esophagus and result in acid reflux. The sphincter dysfunction, especially the lower esophageal sphincter can be treated with certain medications and surgeries. If you are dealing with severe symptoms of GERD and suspecting a sphincter dysfunction, then make sure to reach your healthcare provider and get yourself treated well.

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