Esophageal motility disorder refers to any medical condition that disrupts the coordinated movement of the esophagus, the muscular tube connecting the mouth to the stomach. This dysfunction can impede the smooth passage of food and liquids, leading to symptoms such as difficulty swallowing, chest pain, and regurgitation. These disorders arise when the intricate muscular contractions and nerve signals within the esophagus do not function correctly.
How the Esophagus Functions
The esophagus transports swallowed food and liquids from the pharynx to the stomach. This process begins with the opening of the upper esophageal sphincter, a ring-shaped muscle at the top of the esophagus, allowing the swallowed material to enter. Once inside, wave-like muscle contractions, known as peristalsis, propel the food downward.
This coordinated muscular action pushes the bolus towards the stomach. At the lower end of the esophagus, the lower esophageal sphincter (LES) relaxes in response to the approaching food, permitting its entry into the stomach. Between swallows, the LES typically remains closed to prevent stomach acid from refluxing back into the esophagus.
Direct Causes of Motility Disorders
Some esophageal motility disorders stem directly from issues within the esophagus itself, affecting its muscles or the nerves controlling them. Achalasia is one such condition, characterized by the degeneration of nerve cells, specifically nerve cells in the esophageal wall. This nerve damage prevents the lower esophageal sphincter from relaxing properly and impairs the wave-like muscle contractions (peristalsis) in the main body of the esophagus. The reason for this nerve degeneration is often unknown (idiopathic), though autoimmune responses or viral infections are theorized as triggers.
Diffuse esophageal spasm (DES) represents another primary motility disorder, involving uncoordinated and sometimes powerful contractions of the esophageal muscles. Instead of a smooth, progressive wave, these contractions are irregular or simultaneous, which hinders the effective movement of food. Individuals with DES frequently experience chest pain and difficulty swallowing, which can be exacerbated by very hot or cold foods. Its cause is often unclear (idiopathic), but some cases may involve disruptions in nerve signals.
Other direct causes include hypercontractile esophagus, sometimes referred to as “jackhammer esophagus” or “nutcracker esophagus,” where muscle contractions are excessively strong. These forceful contractions, while often coordinated, can lead to chest pain and difficulty swallowing. Conversely, some primary disorders involve absent or very weak contractions, leading to ineffective movement of food through the esophagus.
Underlying Conditions and Other Factors
Beyond disorders originating directly in the esophagus, systemic medical conditions and external factors can contribute to or worsen esophageal motility issues. Diabetes mellitus, for example, can impact esophageal function due to nerve damage caused by diabetic neuropathy. This can result in reduced amplitude of esophageal contractions and slower peristaltic velocity.
Neurological disorders also commonly lead to swallowing difficulties by affecting the nerves and muscles involved in the process. Conditions such as Parkinson’s disease, multiple sclerosis, stroke, amyotrophic lateral sclerosis (ALS), and cerebral palsy can impair the coordinated movements necessary for efficient swallowing and esophageal transport. These conditions disrupt the central nervous system’s control over the complex swallowing mechanism.
Autoimmune diseases, where the immune system attacks its own tissues, can similarly affect esophageal motility. Scleroderma is a prominent example, causing fibrous tissue to replace healthy muscle in the esophagus, leading to weakened contractions and a lower esophageal sphincter that may remain abnormally open. Other autoimmune conditions like lupus can also contribute to esophageal dysfunction.
Chronic gastroesophageal reflux disease (GERD) can also impact esophageal motility. Persistent exposure to stomach acid can damage the esophageal lining, leading to inflammation and impaired muscle function. This damage can contribute to ineffective esophageal motility. Eosinophilic esophagitis (EoE), an allergic inflammatory condition, is another cause where eosinophils accumulate in the esophageal lining. This inflammation can lead to scar tissue and narrowing, making swallowing difficult and impacting motility.
Certain medications can affect esophageal muscle tone and nerve signals, causing or exacerbating motility problems. Previous surgical procedures involving the esophagus can also alter its normal function or nerve supply. Finally, the aging process can lead to some decline in esophageal muscle strength and coordination, making older individuals more susceptible to motility issues. While not a disease, these age-related changes can lead to swallowing difficulties.