An esophageal stricture is defined as an abnormal narrowing of the esophagus, the muscular tube responsible for moving food and liquids from the throat to the stomach. This condition often results in dysphagia, which is the medical term for difficulty swallowing, as the reduced diameter of the passageway obstructs the normal transit of a food bolus. The underlying reason for this narrowing is always the formation of scar tissue, or fibrosis, which replaces the normally flexible, elastic tissue of the esophageal wall. These strictures arise from various underlying issues that all share the common outcome of causing damage and triggering a long-term scarring response within the esophageal lining.
Chronic Inflammatory Conditions
The most frequent cause of benign esophageal narrowing originates from long-term, ongoing inflammatory processes, where repetitive irritation leads to scar tissue formation. Peptic strictures, which account for the vast majority of benign cases, are the end result of chronic Gastroesophageal Reflux Disease (GERD). Repeated exposure of the esophageal lining to acidic stomach contents causes persistent damage, particularly near the connection point between the esophagus and the stomach, known as the squamocolumnar junction. This chronic inflammation triggers the proliferation of myofibroblasts and the excessive deposition of collagen, a process called fibrosis, which ultimately decreases the elasticity and diameter of the esophageal lumen.
The severity of the stricture is directly related to the duration of untreated acid exposure, which is often compounded by a dysfunctional lower esophageal sphincter. Another distinct inflammatory cause is Eosinophilic Esophagitis (EoE), an immune-mediated allergic disease. In EoE, the esophagus becomes infiltrated with large numbers of eosinophils, a type of white blood cell, in response to certain food or environmental allergens. These eosinophils release inflammatory and profibrotic mediators, which stimulate a remodeling cascade in the esophageal wall. This process leads to subepithelial fibrosis, resulting in a loss of compliance and a reduction in the functional diameter of the esophagus.
Damage from Acute Injury and Trauma
Esophageal strictures can result from a single, sudden, and severe insult that causes extensive, deep tissue destruction. This type of damage is most commonly observed following the accidental or intentional ingestion of caustic substances like household cleaners containing strong alkalis or acids. Alkaline agents, such as lye, cause a severe type of injury called liquefaction necrosis, which allows the corrosive substance to penetrate deeply and rapidly through the esophageal wall. Acidic substances induce coagulation necrosis, which may form a protective eschar but still results in significant injury. The acute destruction is followed by a prolonged cicatrization phase, where the extensive tissue loss heals with dense, constricting scar tissue, often resulting in a complex and refractory stricture.
Other forms of acute trauma that can lead to focal strictures include deep ulceration caused by a foreign body, such as a sharp bone or a large, lodged pill. While thermal injuries are rare, severe, prolonged contact with extremely hot substances can similarly cause deep burns. The severity of the stricture is determined by the depth and circumference of the initial tissue destruction, which dictates the amount of subsequent scar tissue that forms during healing.
Strictures Resulting from Medical Treatments
Strictures can develop as an unintended consequence of necessary medical interventions, a category known as iatrogenic causes. A major factor is radiation therapy, which is used to treat cancers of the head, neck, or chest. The high-energy ionizing radiation targets and destroys cancerous cells but also damages healthy esophageal tissue indiscriminately. The radiation causes DNA damage and triggers a sustained inflammatory response in the esophageal lining, leading to microvascular injury and endarteritis. This chronic cellular damage results in progressive fibrosis and subsequent narrowing of the esophageal lumen, typically occurring three to eight months following treatment. These radiation-induced strictures are often complex and difficult to manage due to the dense, ischemic nature of the scar tissue.
Post-surgical scarring is another form of iatrogenic stricture, frequently occurring at the site of an anastomosis following an esophagectomy or other reconstructive procedure. The natural wound healing process at the surgical connection point can sometimes be excessive, resulting in a fibrotic ring that narrows the passageway. Even prolonged use of medical devices, such as a nasogastric tube placed over an extended period, can cause localized trauma, deep ulceration, and eventual stricture formation.
Malignancy and Underlying Disease
A separate category of stricture formation involves either the physical presence of abnormal tissue growth or a systemic disease. In the case of malignancy, an esophageal tumor, such as squamous cell carcinoma or adenocarcinoma, physically encroaches upon and obstructs the esophageal lumen. The stricture is a direct result of the tumor bulk and the inflammatory reaction it stimulates, rather than solely a remote scarring process.
Systemic conditions like Scleroderma, also known as systemic sclerosis, can lead to stricture formation through a different pathway. This autoimmune disease causes the body to overproduce collagen, leading to fibrosis and thickening of connective tissues throughout the body, including the esophagus. The disease specifically causes atrophy and replacement of the smooth muscle layer in the distal two-thirds of the esophagus with fibrous tissue. This damage results in severe dysmotility and a weakened lower esophageal sphincter, which in turn leads to severe, long-standing acid reflux. The strictures associated with Scleroderma are often a complication of the resulting GERD, exacerbated by the underlying connective tissue changes.