Oropharyngeal dysphagia involves diseases of the musculoskeletal or nervous system that cause difficulty in the initiation of swallowing. Stroke is the leading cause of oropharyngeal dysphagia; other causes include Parkinson disease, myasthenia gravis, and other long-term neuromuscular disorders. Oropharyngeal dysphagia presents as part of a broader complex of neurological deficits and clinical manifestations related to the underlying disease process, which may include diminished cough reflex, dysarthria, diplopia, ptosis, and hemiparesis.
In esophageal dysphagia, difficulty swallowing is often the main complaint and is caused by localized neuromuscular disorders or obstructive lesions. This article focuses on esophageal dysphagia in adults, including risk factors, epidemiology, pathophysiology, and management.
DEGLUTITION AND ESOPHAGEAL PHYSIOLOGY
Deglutition, the reflexive act of swallowing, requires a complex series of voluntary and involuntary neuromuscular contractions to propagate a food or liquid bolus from the mouth, through the pharynx, and into the stomach. The oropharyngeal stage involves the interaction of the tongue, striated muscles of mastication, and musculature of the posterior oropharynx to prepare the food bolus and pass it from the oral cavity past the cricopharyngeus muscle (the upper esophageal sphincter) into the upper esophagus (Figure 2). This 2-second sequence is controlled by the motor nuclei of cranial nerves V, VII, and XII and the motor and sensory tracts of cranial nerves IX and X.
The adult esophagus is 18 to 26 cm (7 to 8 in) long; when distended, its lumen has internal dimensions of about 2 cm (0.79 in) in the anteroposterior plane and 3 cm (1.2 in) in the lateral plane. The upper third of the esophagus is composed of striated muscle controlled by cranial nerves IX and X; the lower two-thirds is composed of smooth muscle controlled by cranial nerve X in conjunction with the esophageal myenteric nerve plexus. The lower esophageal sphincter is composed entirely of smooth muscle and remains tonically constricted with a pressure of 30 mm Hg.
When a person starts to swallow, the myenteric inhibitory neurons signal relaxation of the lower esophageal sphincter, which persists until the food bolus is propelled though. Two perpendicular layers of muscle, an inner circular and outer longitudinal layer, contract and shorten the esophagus to produce a coordinated peristaltic wave. Primary peristalsis is triggered by the swallowing center in the medulla and pons. The primary peristaltic wave is 30 mm Hg or greater, begins in the pharynx, and forces the food bolus through the esophagus in 6 to 10 seconds. Secondary peristalsis is induced by esophageal distension from retained portions of the food bolus. Receptors in the esophageal lining induce a local reflex response, causing secondary peristaltic waves around the bolus that force it through the esophagus. These waves, controlled by the medulla oblongata, continue until the bolus is cleared. Nonphysiologic, nonperistaltic dysfunctional contractions (termed tertiary contractions), are observed with increasing frequency in older patients and those with long-standing gastroesophageal reflux. On radiographs, this phenomenon is called presbyesophagus.2 Presbyesophagus usually is asymptomatic and thought to be related to decreased ganglion cells in the myenteric plexus, which leads to decreased peristalsis, tertiary contractions, and lower esophageal sphincter dysfunction.
HISTORY AND PHYSICAL EXAMINATION
To differentiate the nature of dysphagia as oropharyngeal or esophageal, consider the onset, type (solid versus liquid dysphagia), duration, severity, and localization of dysphagia. Also consider the circumstances in which the patient experiences dysphagia, its progression, and associated symptoms. Patients with oropharyngeal dysphagia present with difficulty initiating swallowing and may have associated coughing, choking, nasal regurgitation, and tracheobronchial aspiration.3 Patients with esophageal dysphagia report food “sticking” in the throat or upper chest several seconds after swallowing and will point to the suprasternal notch or behind the sternum as the site of obstruction.3 A perceived location of obstruction below the sternum highly correlates with anatomic obstruction such as a ring, mass, or stricture; this correlation is poor for a perceived location of obstruction at or above the sternal notch.1
Chest pain or odynophagia is frequently associated with dysphagia, whether it is related to motor disorders, structural disorders, or reflux disease. In patients with painful swallowing, consider the causes of esophagitis (including reflux, radiation or chemotherapy adverse reactions, swallowing a corrosive substance, infections, or medications). In patients with esophagitis, peristaltic dysfunction is progressively more common with greater degrees of esophagitis. Symptoms more suggestive of an esophageal origin of dysphagia include heartburn, regurgitation, odynophagia, and atypical gastroesophageal reflux disease (GERD) symptoms (dyspnea, chronic cough, hoarseness, throat clearing, sore throat, and globus sensation).
Review the patient's full medical and family history, including long-term illnesses such as neurodegenerative disease, diabetes, and hypertension; current medications; and drug, alcohol, and tobacco use. A history of autoimmune disease or components of “CREST” syndrome (calcinosis, Raynaud syndrome, esophageal dysmotility, sclerodactyly, and telangiectasia) support the diagnosis of scleroderma. Patients with a history of gastritis, hiatal hernia, GERD, or peptic ulcer disease may have esophagitis or peptic stricture. Past caustic or chemical esophageal burns or a history of nasogastric tube placement also can result in stricture formation.
Commonly prescribed medications can cause esophageal dysphagia through direct mucosal injury or by decreasing lower esophageal sphincter tone (Table 1). Foods including alcohol, chocolate, fatty food, peppermint, and onion also can cause decreased lower esophageal sphincter tone or reflux.4
Any form of immune system compromise may predispose the patient to infectious esophagitis. Reviewing the patient's cardiac, respiratory, and abdominal systems may reveal symptoms associated with vascular or mediastinal disease.
The physical examination begins with assessing vital signs for changes related to fever, dehydration, or respiratory distress. Review the patient's body mass index as part of a nutritional assessment, particularly in patients with significant weight loss. The neurologic evaluation should include mental status, motor and sensory function, reflexes, and cranial nerves, particularly those involved with swallowing and the gag reflex. Seek to elicit signs of bulbar or pseudobulbar palsy, including dysarthria, dysphonia, ptosis, tongue atrophy, and hyperactive jaw jerk.3 The neurologic assessment may reveal findings related to the underlying cause of oropharyngeal dysphagia: impaired cognition, new stroke, or long-term illness. Observing the patient swallowing liquids and solids can be helpful. Palpate the patient's neck for thyroid masses and lymphadenopathy. Listen to lung and heart sounds to assess for complications of aspiration or the presence of a pericardial effusion. Evaluate the patient's abdomen for tenderness, masses, and organomegaly. Observe the skin for changes related to scleroderma or other autoimmune or connective tissue diseases. Fecal occult blood may indicate neoplasm or severe esophagitis.
Esophageal dysphagia can be caused by primary or secondary motility disorders, and intrinsic or extrinsic structural lesions.
Primary motility disorders If dysphagia to liquids is the predominant symptom, consider neuromuscular motility disorders. Clinical manifestations of esophageal motility disorders are varied, but dysphagia and chest pain are the most commonly reported symptoms. The chest pain associated with esophageal motility disorders is a severe squeezing retrosternal pain that radiates to the back, neck, jaw, and arms and may interrupt the patient's daily activities. The pain may be related to transient esophageal ischemia, distension, or altered visceral sensation.2 Before evaluating the patient for causes of dysphagia, rule out cardiac causes of the chest pain—GI diagnoses are the most common misdiagnoses for patients with myocardial infarction and acute coronary syndrome.
Evaluate the underlying causes of the patient's dysphagia, including GERD, obesity, metabolic syndrome, esophageal obstruction, and mucosal injury.
Spastic motility disorders of the esophagus are caused by a functional imbalance between excitatory and inhibitory postganglionic pathways disrupting coordinated peristalsis.2
Achalasia occurs in 1 to 3 patients per 100,000 population, commonly presents between ages 30 and 60 years, and has no documented sex or racial predilection.2,5 The disease is characterized by a hypertensive lower esophageal sphincter and the absence of peristalsis in the lower two-thirds of the esophagus due to the progressive loss of inhibitory neurons (starting at the lower esophageal sphincter and extending proximally).2 Symptoms occur due to stasis of ingested food and dilation of the distal esophagus. Patients experience significant, progressive dysphagia for both liquids and solids, which they may attempt to relieve with repeated swallows, Valsalva maneuvers, or positional changes. Emotional stress or rapid eating aggravates the symptoms. Patients also may regurgitate undigested food, particularly at night, and experience coughing, heartburn, weight loss, and aspiration. The chest pain associated with achalasia is thought to be caused by esophageal spasm.
Suspect achalasia in patients with dysphagia to solids and liquids and in those with regurgitation unresponsive to proton pump inhibitor (PPI) therapy.5 Patients with long-standing achalasia have an increased incidence of esophageal squamous cell and adenocarcinoma.2,5
Nutcracker esophagus is the most common motility disorder, accounting for more than 40% of all motility disorders diagnosed.2 In this disease, contractions proceed in a coordinated manner but the amplitude is excessive; patients often report more chest pain than dysphagia.
Diffuse esophageal spasm is characterized by simultaneous uncoordinated contractions of several esophageal segments. This prevents propagation of the food bolus and causes severe retrosternal pain that may last minutes to hours. The condition may be precipitated or worsened by acid reflux, rapid eating, stress or anxiety, hot or cold food, or carbonated drinks. Patients with diffuse esophageal spasm have no documented abnormality in the distribution of myenteric neurons, normal lower esophageal sphincter relaxation, and no obstruction. Diffuse esophageal spasm does not cause the severity of dysphagia seen with achalasia; dysphagia is often intermittent, nonprogressive, and does not cause weight loss. Patients may also report globus sensation, regurgitation, and heartburn.
Nonspecific esophageal motility disorders are a group of manometric abnormalities generally found in patients who are evaluated for heartburn and dysphagia who do not meet specific criteria for other motility disorders.
Secondary motility disorders Systemic diseases can cause esophageal dysmotility.
Scleroderma, a connective tissue disease, involves the esophagus in more than 75% of cases.2 Scleroderma causes smooth muscle atrophy, fibrosis, and sclerosis of the gut wall, resulting in profound hypomotility and a weakened lower esophageal sphincter with severe reflux. Symptoms such as dysphagia, regurgitation, and heartburn reflect the severity of reflux, and erosive esophagitis is observed in about 60% of patients.2 Associated complications include peptic strictures, adenocarcinoma, and Barrett esophagus (metaplasia of the normal squamous epithelium of the lower esophagus to columnar cells as a response to long-standing reflux). Patients with Barrett esophagus are at greatly increased risk for adenocarcinoma.
About 60% of patients with diabetes and evidence of peripheral or autonomic neuropathy have disordered esophageal motility, but few are symptomatic.2
Other systemic diseases associated with disordered peristalsis include Parkinson disease, alcohol abuse, muscular dystrophy, myopathy, and amyloidosis.
Obstructive intrinsic structural lesions Intermittent nonprogressive dysphagia for only solid food suggests an obstructive lesion, most commonly an esophageal ring or web. Both are membranous structures consisting of a thin fold of tissue that at least partially obstructs the esophagus. Rings and webs have been identified in all age groups but generally become symptomatic after age 40 years and are most common in white patients.1,6,7
Schatzki connective tissue B ring, the most common ring, involves the mucosa and submucosa and typically is located at the squamocolumnar junction. Schatzki ring is found incidentally in up to 14% of barium studies and is usually asymptomatic, although it may be associated with heartburn and hiatal hernia.6,8 This type of ring is found in 15% to 26% of patients evaluated for dysphagia.6 Schatzki ring dysphagia has been termed “steakhouse syndrome” because symptoms are most common after eating bread and meat, particularly when the meal is consumed quickly. Meat or food impaction with prolonged inability to pass an ingested bolus (even with ingestion of liquid) is typical of obstructive intrinsic structural lesions.3
Acquired causes of lower esophageal rings include GERD, ingestion of a caustic substance, pill-induced inflammation, and chest radiation therapy.1,6,7
A “ringed” esophagus involves circumferential ring-like structures throughout the esophagus, is a distinct condition from the singular esophageal ring, and is the hallmark finding of eosinophilic esophagitis.6 This allergic disorder is commonly found in white men and is induced by dietary allergens in susceptible patients. Suspect eosinophilic esophagitis in patients with an atopic history of food allergy, asthma, eczema, or allergic rhinitis who present with dysphagia and food impactions with or without heartburn.8 The symptoms of eosinophilic esophagitis and GERD overlap, but a biopsy of esophageal mucosa will reveal infiltration with eosinophils in patients with eosinophilic esophagitis.
Esophageal webs are thin fibrous protrusions of squamous mucosa that transverse the upper esophageal lumen. Asymptomatic webs are found in about 10% of patients, most commonly along the anterior mucosal surface.8 Webs are seen in 5% to 15% of patients being evaluated for dysphagia.6 Esophageal webs are associated with Plummer-Vinson syndrome, an idiopathic disease that puts patients at increased risk for squamous cell esophageal carcinoma. Plummer-Vinson syndrome is found in middle-aged women with iron-deficiency anemia, koilonychia, glossitis, or splenomegaly. Alarming symptoms that are not consistent with rings and webs are progressive dysphagia, weight loss, or anemia. These symptoms are suggestive of malignancy and require prompt evaluation.
Esophageal strictures are caused by any disease that narrows the esophageal lumen through inflammation, neoplasm, or fibrosis. Potential causes include peptic and autoimmune diseases, infection, ingesting a caustic substance, trauma, tumor, medications, and radiation; strictures also can be congenital or iatrogenic.
Extrinsic diseases that compromise the esophageal lumen by direct invasion or lymph node enlargement (such as malignancy) also cause strictures. The dysphagia related to strictures may be nonprogressive, or progress from solid to liquid dysphagia depending on the underlying cause. Peptic strictures located at the squamocolumnar junction caused by long-standing or severe GERD are common. They are generally seen in older white men who report progressive dysphagia, heartburn, odynophagia, food impaction, weight loss, and chest pain. Anastomotic strictures are increasingly being diagnosed after patients undergo esophageal resection for treatment of cancer or Barrett esophagus and radiation-induced strictures.7
The patient is likely to have symptoms related to the underlying cause; patients with obstructive lesions may report changing their diet to soft foods.
Head and neck cancers are the most common malignancies to cause dysphagia, but patients with cancer may have dysphagia caused by esophageal infection or graft-versus-host disease.9 Acute clinical effects of radiation therapy of the neck usually resolve by 3 months posttreatment; however, complex cytokine and inflammatory processes may cause dysphagia even years after treatment is completed.9
Corrosive injury to the esophagus (thermal or chemical burns) can occur after ingesting acidic or alkaline substances, disc batteries, or overheated food or drink. Patients may present with oropharyngeal ulcerations, edema, and erythema with coughing, crying, vomiting, drooling, and varying degrees of respiratory distress and stridor. Identifying the corrosive substance is imperative to anticipating and reducing complications. Alkali ingestion may cause deep liquefaction necrosis with perforation; acid ingestion causes superficial eschar.
Esophagitis (infectious, inflammatory, reflux, or eosinophilic) is also a common cause of intrinsic structural lesions. Infectious esophagitis is most common in immunocompromised patients such as those with a history of HIV/AIDS or hematologic malignancy; patients who've had radiation, chemotherapy, or recent antibiotic use; and patients on immunosuppressive therapies. Candida albicans and Herpes simplex are the two most common causes of infectious esophagitis. Other causes include cytomegalovirus, HIV, varicella zoster, and Epstein-Barr virus. Infectious esophagitis presents primarily with dysphagia and odynophagia, but may also cause fever, nausea, vomiting, epigastric pain, anorexia, and weight loss.
Pill-induced esophagitis can develop hours, days, or weeks after taking a pill, and commonly affects patients with esophageal stenosis or abnormal peristalsis. Retrosternal chest pain from pill-induced esophagitis resolves 1 to 6 weeks after pills are stopped. Controlling acid reflux allows for faster healing.
Esophageal carcinoma is diagnosed in more than 17,000 patients in the United States each year.10 Progressive dysphagia for solids and later liquids over the course of weeks to months is the most common presenting symptom for esophageal carcinoma, and should be strongly suspected when coupled with weight loss, anorexia, and iron-deficiency anemia. Other manifestations include epigastric or chest pain, odynophagia, bleeding, hoarseness from left recurrent laryngeal nerve invasion, hepatomegaly, lymphadenopathy, and respiratory symptoms. Esophageal cancer is most common in men in their 50s and 60s. Risk factors for squamous cell carcinoma (typically found in the upper to middle esophagus) include cigarette smoking and alcohol abuse. Adenocarcinoma, which is most prevalent in the United States, is most commonly found in the middle to lower esophagus; GERD is the most common predisposing factor. Patients with a long-standing history of GERD who have rapidly progressive dysphagia are at risk for Barrett esophagus and adenocarcinoma.
Esophageal diverticula also may cause dysphagia and obstruction. The three types of diverticula are categorized by location and tend to develop slowly over years, presenting in middle-aged to older adults.
* Zenker diverticulum is a hypopharyngeal herniation through Killian triangle in patients with a stenotic cricopharyngeus muscle. Small diverticula are usually asymptomatic, but larger ones may be associated with regurgitation of undigested food, chronic cough, dysphagia to solids and liquids, a bulge in the throat, or halitosis.
* Mid-esophageal or traction diverticula are often asymptomatic and occur in patients with contiguous mediastinal lymphadenopathy, such as occurs in tuberculosis, sarcoidosis, or histoplasmosis.
* Epiphrenic diverticula occur in the distal esophagus, and are often associated with achalasia or a distal esophageal stricture.
Obstructive extrinsic structural lesions With advancing age, the aorta dilates, elongates, and becomes tortuous; cardiac enlargement is common; and the spine tends toward kyphosis. These changes can affect the esophagus. Large pericardial effusions, often due to trauma or malignancy, may compress the esophagus. Thoracic and hilar lymphadenopathy or mediastinal masses are also in proximity to the esophagus and may cause dysphagia.
Laboratory evaluation is guided by the differential diagnosis. A complete blood cell count may reveal infectious, neoplastic, or inflammatory conditions. Thyroid function tests may reveal changes consistent with hyperthyroidism or thyroid cancer that could cause a compressive obstruction. Patients with dysphagia can initially undergo either endoscopic or radiologic evaluation, depending on their clinical history and clinician preference.
Most patients with dysphagia initially have barium esophagography, although the best approach is a combination of radiographic and endoscopic studies.11 Conventionally, practice is moving toward endoscopy as the primary and direct imaging assessment. A barium swallow exposes patients to radiation, delays definitive diagnosis in most patients, and increases the cost of evaluating dysphagia, because nearly all patients who undergo barium swallow as the first test will eventually need endoscopy.5
A barium contrast study of the esophagus, stomach, and duodenum is often the initial step in the workup for dysphagia. The study is noninvasive, inexpensive, has few complications, and does not require sedation. Barium studies also are better than endoscopy for diagnosing structural and motility disorders and assessing esophageal emptying (Table 2).11 Barium studies are more sensitive in detecting subtle abnormalities, particularly mucosal rings, obstructive lesions, or strictures, as well as compression caused by structures external to the esophagus.8,11,12 The evaluation includes a modified barium swallow to study the oropharynx, an esophagram for the esophagus, and a timed study to evaluate esophageal emptying.11 Administration of a 13-mm barium pill is also useful, as impaction on swallowing indicates a high-grade obstruction and need for esophageal dilation. An air-contrast mucosal examination allows evaluation of mucosal granularity or thickening, masses, erosions, ulcers, and hiatal hernias.11 The sensitivity of barium radiography compared with endoscopy for detecting esophagitis ranges from 22% to 95%; radiography has high detection rates for higher grades of esophagitis, but misses the more common shallow ulcerations and erosions that can be detected by endoscopy.8
The main limitation of barium radiography is that positive or negative studies are likely to be followed by endoscopy to clarify positive findings or to add certainty to negative findings.11 Barium studies are contraindicated in patients with suspected complete or near complete esophageal obstruction and those with suspected food bolus impactions and foreign object ingestions.5 For those patients, endoscopy is diagnostic and therapeutic.
Esophageal manometry, or high-resolution esophageal pressure topography, evaluates peristalsis and lower esophageal sphincter relaxation, and is the gold standard for assessing motility disorders. This test is not a primary investigation, but is performed when diagnosis has not been achieved by careful history, barium radiology, or endoscopy (Table 3).3,8,12 Many manometry studies conducted to evaluate dysphagia and/or chest pain reveal minor abnormalities insufficient for diagnosis (classified as nonspecific esophageal motility disorders). These include ineffective or failed peristalsis; nontransmitted waves; retrograde, repetitive, prolonged, low, or high-amplitude contractions; hypertensive peristalsis; and isolated incomplete lower esophageal sphincter relaxation.2 These findings are of unclear significance and usually not correlated to symptoms; commonly patients have concurrent GERD, depression, anxiety, or irritable bowel syndrome, which may be precipitant factors.8 Combined recordings of esophageal pH levels and intraluminal esophageal pressure may aid in diagnosis in patients with reflux-induced esophageal spasm.
Endoscopy or esophagogastroduodenoscopy (EGD) provides high-quality color images of the esophageal, gastric, and duodenal lumens and has the therapeutic advantage of allowing for biopsy, sclerotherapy, dilation, and cautery. The main disadvantage is the sedation needed for the procedure. Compared with barium radiograph, endoscopy has increased sensitivity for detecting even mild grades of esophagitis and color changes associated with Barrett esophagus.8 Endoscopy is insensitive for diagnosing primary motility disorders, but is necessary to exclude neoplastic and inflammatory conditions of the esophageal mucosa that can produce patterns of achalasia or diffuse esophageal spasm.2,5
Endoscopy also can confirm acute obstructive lesions such as impacted food bolus or foreign body, detect infections, and evaluate caustic or corrosive esophageal injury. Candida esophagitis has a characteristic appearance of white plaques with friability, herpes esophagitis presents as vesicles and small, punched-out ulcerations, and cytomegalovirus infection appears as large, solitary shallow ulcers or multiple discrete lesions with otherwise normal mucosa, particularly in the distal esophagus.8 The diagnostic appearance of esophageal infection can be coupled with biopsy and serological testing. If rings, webs, or strictures are suspected, endoscopy may be planned with fluoroscopic guidance or small-caliber endoscopes to dilate.5
Endoscopy is also necessary for the early diagnosis of esophageal cancer, which requires a biopsy. Routine biopsy of rings and webs is not necessary. To rule out eosinophilic esophagitis, obtain mucosal biopsies routinely when evaluating unexplained dysphagia, even if no lesions are evident on endoscopy.3 Characteristic endoscopic findings for eosinophilic esophagitis include multiple esophageal rings, linear furrows, fibrosis, punctate exudates, and stricture with histological eosinophilia in the esophageal mucosa.
The management of esophageal dysphagia depends on the underlying cause and usually involves medications or surgery (Table 4). Managing complications is imperative, including identifying the risk for aspiration and metaplasia and providing prevention education and surveillance as necessary.
Dietary changes with softer food; smaller, less obstructive boluses; and postural measures may be helpful. Oral feeding is preferred, but care must be taken to monitor the patient's fluid, electrolyte, and nutrition needs. Alternate nutritional support may be considered. Patient referral is indicated when the cause of dysphagia is unclear or if further diagnostic or therapeutic expertise is required.
The differential diagnosis of esophageal dysphagia is extensive and the condition is seen in a variety of medical and surgical specialties. Dysphagia is also a key symptom in several malignancies, making it an important symptom to evaluate. The cause frequently can be correctly anticipated through a full history and physical examination, and a combination of radiologic and endoscopic testing is often definitive. Physician assistants play an essential role in evaluating adults with esophageal dysphagia and should be able to recognize risk factors, perform an appropriate workup, and provide initial management and referral.
3. Hirano I, Kahrilas PJ. Dysphagia. In: Longo DL, Fauci AS, Kasper DL, et al., eds. Harrison's Principles of Internal Medicine
. 18th ed. New York, NY: McGraw-Hill; 2012. Accessed May 5, 2013.
4. Spieker MR. Evaluating dysphagia. Am Fam Physician
5. Vaezi MF, Pandolfino JE, Vela MF. ACG clinical guideline: diagnosis and management of achalasia. Am J Gastroenterol
6. Smith MS. Diagnosis and management of esophageal rings and webs. Gastroenterol Hepatol (N Y)
7. Baron TH. Management of benign esophageal strictures. Gastroenterol Hepatol (N Y)
8. Kahrilas PJ, Hirano I. Diseases of the esophagus. In: Longo DL, Fauci AS, Kasper DL, et al., eds. Harrison's Principles of Internal Medicine
. 18th ed. New York, NY: McGraw-Hill; 2012.
10. Yamamoto M, Weber JM, Karl RC, Meredith KL. Minimally invasive surgery for esophageal cancer: review of the literature and institutional experience. Cancer Control
11. Allen BC, Baker ME, Falk GW. Role of barium esophagography in evaluating dysphagia. Cleve Clin J Med
13. Salvador R, Costantini M, Rizzetto C, Zaninotto G. Diffuse esophageal spasm: the surgical approach. Dis Esophagus
Keywords:© 2014 American Academy of Physician Assistants.
esophageal dysphagia; motility disorder; cancer; rings and webs; scleroderma; achalasia