Dysphagia - Causes and Differential Diagnosis

Understanding Dysphagia: Causes and Differential Diagnosis Introduction Dysphagia—difficulty swallowing—is a clinical symptom that can result from many different underlying conditions. Understanding the various causes is essential because the mechanism of dysphagia differs depending on whether the problem originates in the nervous system, the muscular structures, or the esophagus itself. By organizing causes into distinct categories, you can systematically approach a patient with dysphagia and narrow down the differential diagnosis. Neurological and Muscular Causes These conditions impair the nerve signals or muscle function needed for coordinated swallowing movements. Xerostomia (dry mouth) in conditions like Sjögren's syndrome interferes with swallowing because saliva lubricates food and aids in the initial stages of swallowing. Without adequate saliva, the bolus becomes difficult to form and move through the pharynx. Bulbar palsy and pseudobulbar palsy involve damage to the brainstem (bulbar region) or the neural pathways controlling swallowing muscles. These conditions paralyze or weaken the muscles of the pharynx and soft palate, making the coordinated movements of swallowing impossible. Post-vagotomy dysphagia occurs because the vagus nerve, which innervates many swallowing muscles, is damaged during surgery. Myasthenia gravis is an autoimmune condition that causes muscle weakness by blocking signals at the neuromuscular junction. Because swallowing requires sustained muscle contraction, patients with myasthenia gravis experience progressive difficulty as they swallow repeatedly. Structural and Mechanical Causes These conditions create physical obstructions or compressions that narrow or block the pharynx and upper esophagus. Impacted foreign bodies in the esophageal lumen obviously obstruct food passage. Pharyngitis causes swallowing difficulty through inflammation and pain in the pharyngeal tissues. Pharyngeal spasms involve involuntary muscle contractions that interfere with the coordinated muscular movements necessary for swallowing. Retropharyngeal abscess is a collection of pus behind the pharynx that takes up space and can compress swallowing structures. Paterson-Kelly syndrome (also called Plummer-Vinson syndrome) involves upper esophageal webs—thin membranes that partially obstruct the esophagus—along with iron deficiency anemia. This is an important condition to recognize. Cervical lymph node enlargement and thyroid malignancy compress the esophagus from the outside. Retrosternal goitre (an enlarged thyroid extending into the chest) similarly compresses esophageal structures. Zenker's diverticulum is an outpouching of the posterior pharyngeal wall that can trap food and interfere with normal swallowing mechanics. <extrainfo> Aortic aneurysm compressing the esophagus, mediastinal growths (tumors in the chest cavity), hiatus hernia (where the stomach herniates through the diaphragm), and tight hiatus repairs or laparoscopic fundoplication (surgical repairs that become too tight) are less common but important structural causes to be aware of. </extrainfo> Esophageal Lumen Disorders These conditions affect the esophagus itself—either its structural integrity or its ability to contract properly. Benign strictures are narrowings of the esophageal lumen caused by scarring from reflux esophagitis, swallowed corrosives, tuberculosis, radiotherapy, or systemic sclerosis. The scar tissue creates a permanently narrowed passageway that obstructs food passage. Achalasia is a primary motility disorder where the lower esophageal sphincter (LES) fails to relax properly. This means swallowed food cannot enter the stomach, and the esophagus above the sphincter becomes dilated as food accumulates. Patients characteristically have difficulty swallowing both solids and liquids. Esophageal webs and rings are thin mucosal structures that partially occlude the esophageal lumen. Webs are more common in the upper esophagus and may be associated with iron deficiency (Paterson-Kelly syndrome). Rings are thicker and can occur at the gastroesophageal junction. Esophageal cancer progressively narrows the esophageal lumen as the tumor grows. Esophageal leiomyoma is a benign smooth muscle tumor that can obstruct the esophagus. Infectious causes include Candida esophagitis (fungal infection, especially in immunocompromised patients) and tuberculosis (though listed under strictures, TB can also cause acute inflammation). Crohn's disease can affect the esophagus, causing inflammation and stricture formation. Eosinophilic esophagitis is an allergic/inflammatory condition characterized by eosinophil infiltration of the esophageal wall, leading to inflammation, strictures, and impaired motility. Drug-Induced Causes Opioids impair the coordinated muscle contractions needed for swallowing and increase the overall risk of dysphagia. This is particularly important to remember when patients on pain management medications develop swallowing difficulties. Key Differential Diagnoses to Consider When evaluating a patient with dysphagia, certain conditions should always be on your differential: Systemic sclerosis (scleroderma) affects esophageal smooth muscle, causing fibrosis and impaired motility, particularly in the lower esophagus. Polymyositis is an inflammatory muscle disease that can impair pharyngeal and esophageal muscles. Neurological conditions causing dysphagia include stroke (which damages brain regions controlling swallowing), Wernicke encephalopathy (from severe thiamine deficiency), Parkinson's disease (which impairs the coordinated movements needed for swallowing), multiple sclerosis (which can affect cranial nerves controlling swallowing), and amyotrophic lateral sclerosis (ALS) (which progressively paralyzes muscles including those for swallowing). Cervical spondylosis (degenerative changes in the cervical spine) can compress the esophagus from the outside, particularly if there is significant osteophyte formation. The key to differential diagnosis is determining whether the dysphagia is oropharyngeal (difficulty initiating swallowing, choking, coughing during swallowing—suggesting neurological/muscular or upper structural causes) or esophageal (sensation of food sticking in the chest after swallowing—suggesting esophageal motility disorders or obstructive lesions).