Esophageal function testing should be used for differential diagnosis of dysphagia. Dysphagia can be the consequence of hypermotility or hypomotility of the muscles of the esophagus. Decreased esophageal or esophagogastric junction distensibility can provoke dysphagia. The most well established esophageal dysmotility is achalasia. Other motility disorders can also cause dysphagia. High-resolution manometry (HRM) is the gold standard investigation for esophageal motility disorders. Simultaneous measurement of HRM and intraluminal impedance can be useful to assess motility and bolus transit. Impedance planimetry measures distensibility of the esophageal body and gastroesophageal junction in patients with achalasia and eosinophilic esophagitis.
Key points
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Esophageal function testing should be used for differential diagnosis of dysphagia after exclusion of structural causes.
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High-resolution manometry increases diagnostic yield and can predict treatment outcomes in achalasia.
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Impedance planimetry can help to identify abnormalities in esophagogastric junction distensibility in achalasia and eosinophilic esophagitis.
Introduction
Dysphagia is defined as a difficulty (or a sensation of difficulty) of food passage, which may be difficulty with initiating a swallow (oropharyngeal dysphagia) or the sensation that foods and/or liquids are hindered in their passage from the mouth to the stomach (esophageal dysphagia). This distinction can be made from a careful medical history (oropharyngeal vs esophageal) in about 80% to 85% of cases. This article discusses the use of esophageal function testing in the context of esophageal dysphagia.
Esophageal dysphagia may have structural/obstructive causes, secondary to motility disorders, or may be predominantly sensory. In a patient presenting with dysphagia the priority is to exclude a structural cause such as an esophageal malignancy. Hence, if the history is suggestive, the first clinical assessments for dysphagia should be endoscopy and/or barium swallow. At endoscopy, eosinophilic esophagitis can also be diagnosed or excluded by way of esophageal biopsy. Box 1 summarizes common causes of dysphagia that should be excluded before esophageal function testing. There are other rare causes of structural esophageal dysphagia such as lymphocytic esophagitis, esophageal compression by cardiovascular abnormalities, or esophageal involvement of Crohn disease, which can be considered if medical history is suggestive.
Tumors (esophageal, lung, lymphoma)
Vascular compression (aortic, auricular)
Esophageal rings and webs
Chemical or radiation injury
Peptic stricture
Infectious esophagitis (herpes virus, Candida albicans )
Eosinophilic esophagitis
After exclusion of structural causes for dysphagia, esophageal function testing is used to assess motility disorders. Dysphagia can be the consequence of hypermotility or hypomotility of the circular and/or longitudinal muscle layers of the esophagus. It has recently been shown that decreased esophageal or esophagogastric junction (EGJ) distensibility can provoke dysphagia. The most well-established esophageal dysmotility is achalasia. Other motility disorders, including diffuse esophageal spasm, hypercontractile esophagus, and severe hypomotility can also cause dysphagia. High-resolution manometry (HRM) is currently regarded as the gold standard investigation to identify and classify esophageal motility disorders. Simultaneous measurement of HRM and intraluminal impedance (high-resolution impedance manometry [HRIM]) can be useful to assess both motility and bolus transit. Impedance planimetry (EndoFlip) has recently been introduced to measure distensibility of the esophageal body and EGJ in patients with achalasia and eosinophilic esophagitis. This article discusses the use of esophageal function testing in patients with esophageal dysphagia after exclusion of structural abnormalities by normal endoscopy and or radiological examination.
Introduction
Dysphagia is defined as a difficulty (or a sensation of difficulty) of food passage, which may be difficulty with initiating a swallow (oropharyngeal dysphagia) or the sensation that foods and/or liquids are hindered in their passage from the mouth to the stomach (esophageal dysphagia). This distinction can be made from a careful medical history (oropharyngeal vs esophageal) in about 80% to 85% of cases. This article discusses the use of esophageal function testing in the context of esophageal dysphagia.
Esophageal dysphagia may have structural/obstructive causes, secondary to motility disorders, or may be predominantly sensory. In a patient presenting with dysphagia the priority is to exclude a structural cause such as an esophageal malignancy. Hence, if the history is suggestive, the first clinical assessments for dysphagia should be endoscopy and/or barium swallow. At endoscopy, eosinophilic esophagitis can also be diagnosed or excluded by way of esophageal biopsy. Box 1 summarizes common causes of dysphagia that should be excluded before esophageal function testing. There are other rare causes of structural esophageal dysphagia such as lymphocytic esophagitis, esophageal compression by cardiovascular abnormalities, or esophageal involvement of Crohn disease, which can be considered if medical history is suggestive.
Tumors (esophageal, lung, lymphoma)
Vascular compression (aortic, auricular)
Esophageal rings and webs
Chemical or radiation injury
Peptic stricture
Infectious esophagitis (herpes virus, Candida albicans )
Eosinophilic esophagitis
After exclusion of structural causes for dysphagia, esophageal function testing is used to assess motility disorders. Dysphagia can be the consequence of hypermotility or hypomotility of the circular and/or longitudinal muscle layers of the esophagus. It has recently been shown that decreased esophageal or esophagogastric junction (EGJ) distensibility can provoke dysphagia. The most well-established esophageal dysmotility is achalasia. Other motility disorders, including diffuse esophageal spasm, hypercontractile esophagus, and severe hypomotility can also cause dysphagia. High-resolution manometry (HRM) is currently regarded as the gold standard investigation to identify and classify esophageal motility disorders. Simultaneous measurement of HRM and intraluminal impedance (high-resolution impedance manometry [HRIM]) can be useful to assess both motility and bolus transit. Impedance planimetry (EndoFlip) has recently been introduced to measure distensibility of the esophageal body and EGJ in patients with achalasia and eosinophilic esophagitis. This article discusses the use of esophageal function testing in patients with esophageal dysphagia after exclusion of structural abnormalities by normal endoscopy and or radiological examination.
Dysphagia associated with esophageal motility disorders defined in the Chicago Classification
Achalasia
The most established esophageal dysmotility is achalasia. At endoscopy, achalasia can be suggested by esophageal food residue, appearance of esophageal body, and tightness of the lower esophageal sphincter (LES). HRM should be used to confirm diagnosis of achalasia and to identify the subtype of achalasia.
The Chicago Classification criteria of esophageal motility disorders are currently the standard reference for HRM classification. According to this classification, 3 achalasia subtypes (shown in Fig. 1 ) are defined. As expected in achalasia, each is characterized by a failed relaxation of the lower esophageal sphincter during swallows (as determined on HRM by an LES integrated relaxation pressure [IRP], of >15 mm Hg), and by an absence of ordered peristalsis. In type I (classic) achalasia the IRP greater than or equal to 15 mm Hg is associated with a complete absence of esophageal pressure: 100% failed peristalsis. In type II (achalasia with esophageal compression) there is an IRP greater than or equal to 15 mm Hg and at least 20% of wet swallows associated with columns of panesophageal pressurization with greater than 30 mm Hg Type III (spastic achalasia) is defined as an IRP greater than or equal to 15 mm Hg with at least 20% of wet swallows associated with either a preserved fragment of distal peristalsis or a premature (spastic, distal latency <4.5 seconds) contraction.
As well as providing an excellent means of diagnosis, HRM can help predict outcome and guide choice of clinical intervention in achalasia. It has been shown that type II achalasia has the best outcome to treatment, followed by type I, then type III. A study by Boeckxstaens and colleagues showed that for type II and I achalasia outcomes were similar for pneumatic dilatation and surgical myotomy (although young men tend to do better with myotomy). In type III achalasia, outcomes are better with myotomy. Data regarding subtype outcomes from peroral endoscopic myotomy (POEM) are awaited.
Persistent Dysphagia After Treatment in Achalasia
A significant group of patients with achalasia present with recurrent dysphagia months or several years after successful initial treatment. It is common to perform esophageal function testing on these patients. The most useful tests in this situation (again, after excluding a structural cause) are HRM and a timed barium esophagram. Perhaps the most important question is whether there is residual increased pressure at the EGJ. Patients may have persistent increased resistance at the EGJ either because of increased residual EGJ pressures or decreased distensibility resulting in bolus retention. It is expected that peristaltic activity is still not present. The timed barium esophagogram (TBE) is a simple fluoroscopic evaluation of bolus clearance of esophagus, and is often a useful adjunct to HRM. It involves taking multiple sequential films at predefined time intervals after swallowing a fixed volume of a barium solution of a specific density. After swallowing, upright radiographs are usually taken at 1, 3, and 5 minutes to assess barium clearance.
The patient with dysphagia after treatment of achalasia with a moderate to high IRP and a retained barium column on TBE requires retreatment. Barium column stasis on TBE predicts recurrent symptoms in patients with long-standing achalasia.
Esophageal impedance can also give an idea of the level of liquid retention. Cho and colleagues recently reported an excellent agreement between TBE and HRIM for assessing bolus retention at 5 minutes. As more data and confidence in the technique are gained it is possible that HRIM will be used as a single test to assess bolus retention and motor function in the management of treated achalasia.
The functional lumen imaging probe (EndoFLIP) uses impedance planimetry to calculate luminal diameters and, together with intraluminal pressure measurements, can be used to calculate distensibiltiy. EndoFLIP has been used to measure distensibility of the EGJ or esophageal body. EGJ distensibility is impaired in patients with achalasia, and is associated with the degree of esophageal emptying and clinical response. As such, it can be used to evaluate treatment efficacy in achalasia. At present, impedance planimetry is only available in a few centers, but it may have the potential to guide therapy in the future if outcome studies are performed.
In summary, evaluation of patients with achalasia and recurrent symptoms after treatment can be widely performed using TBE and HRM with or without impedance. Symptomatic patients with persistent retention on TBE should be retreated. Whether asymptomatic patients with abnormal TBE, detected during routine follow-up, should be treated remains controversial.
EGJ Outflow Obstruction
Some patients with dysphagia without initial endoscopic or radiologic evidence of structural obstruction display increased IRP (as in achalasia) and normal peristalsis (therefore excluding a diagnosis of achalasia) during HRM. This pattern is classified as EGJ outflow obstruction. A study reported that among 1000 consecutive HRM studies, 16 patients fulfilled the criteria characterized by impaired EGJ relaxation, often accompanied by increased intrabolus pressure, and intact peristalsis.
In some patients the cause of EGJ outflow obstruction is mechanical obstruction ( Box 2 ). It is recommended that patients with this motility pattern have endoscopic examination (if not already performed) and computed tomography (CT) or endoscopic ultrasonography evaluation of the EGJ. Note that patients with hiatal hernias are within this group because it has been shown that sliding hiatus hernias alter the pressure dynamics through the EGJ. Patients with an EGJ outflow obstruction after surgical fundoplication are discussed later.
EGJ mucosal/submucosal neoplasm
Fibrotic stenosis (eg, after inflammation/radiotherapy)
Eosinophilic esophagitis
Obstructing esophageal varices
Sliding hiatus hernia
After fundoplication a
a Postsurgical obstruction is not covered by the Chicago Classification.
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