AUTHOR AND EDITOR INFORMATION

Section 1 of 12  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

INTRODUCTION

Section 2 of 12  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Background

Achalasia is an esophageal motor disorder characterized by increased lower esophageal sphincter (LES) pressure, diminished-to-absent peristalsis in the distal portion of the esophagus composed of smooth muscle, and lack of a coordinated LES relaxation in response to swallowing.

Primary achalasia is the most common subtype and is associated with loss of ganglion cells in the esophageal myenteric plexus. These important inhibitory neurons induce LES relaxation and coordinate proximal-to-distal peristaltic contraction of the esophagus.

Secondary achalasia is relatively uncommon. This condition exists when a process other than intrinsic disease of the esophageal myenteric plexus is the etiology. Examples of maladies causing secondary achalasia include certain malignancies, diabetes mellitus, and Chagas disease.

Sir Thomas Willis first described achalasia in 1674. Willis successfully treated a patient by dilating the LES with a cork-tipped whalebone. Not until 1929 did Hurt and Rake first realize that the primary pathophysiology resulting in achalasia was a failure in LES relaxation.

Pathophysiology

The exact etiology of achalasia is not known. The most widely accepted current theories implicate autoimmune disorders, infectious diseases, or both. The last decade has witnessed much progress in the understanding of the cellular and molecular derangements in achalasia.

Degeneration of the esophageal myenteric plexus of Auerbach is the primary histologic finding. However, with early achalasia, a mixed inflammatory infiltrate of T cells, mast cells, and eosinophils is found in association with myenteric neural fibrosis and with a selective loss of inhibitory postganglionic neurons from the Auerbach plexus. In these patients with early achalasia, neurons of the myenteric plexus are relatively well preserved.

The inhibitory neurons produce nitric oxide (NO) and vasoactive intestinal peptide (VIP). NO and VIP are inhibitory neurotransmitters responsible for relaxation of the LES and for coordinated esophageal peristalsis. The loss of inhibitory neurons allows unopposed excitatory stimulation by postganglionic cholinergic neurons of the Auerbach plexus, which leads to a failure in LES relaxation and, eventually, to aperistalsis of the distal esophagus due to loss of the esophageal body latency gradient. Essentially, this means that this portion of the esophagus is unable to relax and subsequently generate a proper, sequential peristaltic wave.

Clinically important features defined by this pathophysiology include the following:

• Peristalsis in the distal smooth muscle segment of the esophagus may be lost. Contractions occur, but they are weak; simultaneous; uncoordinated; and, therefore, nonpropulsive.
• The LES fails to relax, either partially or completely.
• LES pressure is elevated in some patients.
• The coordination of LES relaxation in response to swallowing and esophageal contraction is lost.

Frequency

United States

Achalasia is a relatively uncommon disease. In the United States, the incidence and prevalence approximate international rates.

International

Mayberry and Rhodes described the demographics of achalasia for the city of Cardiff, England, in 1926-1977 (Mayberry, 1980). The incidence of achalasia is 4-6 cases per million persons. The disease prevalence is approximately 8 cases per million population. Mayberry and Atkinson also estimated an annual incidence of 1-2 cases per 200,000 persons in the area of Nottingham, England (Mayberry, 1985). Rates may be slightly higher in South America because of the prevalence of Chagas disease there.

Mortality/Morbidity

• Failure of the LES to relax and decrements in esophageal peristalsis lead to stasis and the retention of foodstuffs and upper gastrointestinal secretions in the esophagus. The primary morbidity associated with this effect is esophagitis, which is readily recognized on endoscopic examination.
• The mass of pooled secretions and solid materials places the patient at risk for aspiration. According to Vantrappen and associates, as many as 30% of patients with achalasia report nocturnal coughing episodes (Vantrappen, 1971). Nocturnal coughing can lead to aspiration pneumonia, which is a serious complication.
• Patients with achalasia are at increased risk for esophageal carcinoma, compared with the general population. According to Wychulis et al and Lortat-Jacob et al, 2-7% of patients with achalasia have an esophageal carcinoma (Wychulis, 1971; Lortat-Jacob, 1969). Esophageal carcinoma and a greatly dilated esophagus are found more frequently in patients with long-standing disease than in patients with early-stage achalasia.

Race

No racial predilection has been described for achalasia.

Sex

Achalasia has no sex predilection.

Age

The incidence of achalasia peaks in those aged 20-40 years. The disease has been diagnosed in infants and in patients well into their 80s (Nihoul-Fekete, 1991).

Anatomy

The average length of the esophagus is 25 cm. As illustrated by Clemente, the esophagus begins just distal to that portion of the inferior pharyngeal constrictor muscle that originates on the cricoid cartilage (Clemente, 1981). The esophagus terminates at the gastroesophageal junction. By convention, the esophagus is typically divided into 3 segments: (1) the cervical esophagus, (2) the thoracic esophagus, and (3) the abdominal esophagus.

The esophageal musculature is composed of an outer longitudinal layer and an inner circular layer. According to Meyer and colleagues, the esophageal musculature is striated in the proximal 5% of the organ (Meyer, 1986). The following 30-40% contains both striated and smooth muscle. The distal 50-60% is composed solely of smooth muscle, which is relevant because the denervation that is the hallmark of achalasia affects the smooth-muscle segment of the esophagus.

Esophageal contraction and peristalsis are mediated by parasympathetic fibers traveling in the vagus nerves. The dorsal motor nucleus of the vagus nerve is responsible for controlling the smooth muscle. In contrast, the nucleus ambiguus controls skeletal muscle.

The esophagus contains 2 major nerve plexuses: the Auerbach plexus and the Meissner plexus. The Auerbach, or myenteric, plexus is embedded between the longitudinal and circular layers of esophageal muscle. Neurons of the Auerbach plexus receive input from vagal preganglionic efferent fibers responsible for smooth muscle control. The Meissner plexus can be found in the submucosa of the esophagus. This plexus of nerves carries afferent information from the esophagus to the vagal parasympathetic and thoracic sympathetic nerves, then onward to the central nervous system.

Clinical Details

Dysphagia is the most common presenting symptom in patients with achalasia. The ingestion of either solids or liquids can result in dysphagia, though dysphagia for solids is more common. Emotional stress and the ingestion of cold liquids are well-known exacerbating or precipitating factors. The natural history varies. Some patients notice that the dysphagia reaches a certain point of severity and then stops progressing. In others, the dysphagia continues to worsen, resulting in decreased oral intake, malnutrition, and inanition. Therefore, weight loss is included in the complex of signs and symptoms associated with achalasia, and it is usually a sign of advanced esophageal disease.

Approximately 25-50% of patients with dysphagia report episodes of chest pain, which are frequently induced by eating. Typically, chest pain is described as being retrosternal; this is a more common feature in patients with early or so-called vigorous achalasia. As the disease progresses and as the esophageal musculature fails, chest pain tends to abate or disappear.

As many as 80-90% of patients with achalasia experience spontaneous regurgitation of undigested food from the esophagus during the course of the disease. Some learn to induce regurgitation to relieve the retrosternal discomfort related to the distended esophagus.

As the disease progresses, the likelihood that aspiration will occur increases. As a result, some patients may present with signs or symptoms of pneumonia or pneumonitis. Lung abscesses, bronchiectasis, and hemoptysis are some of the more severe pulmonary consequences of achalasia-associated aspiration.

Patients with achalasia are at increased risk for esophageal cancer. When esophageal cancer occurs, it is usually found in patients with a long history of achalasia.

Preferred Examination

The radiologic examination of choice in the diagnosis of achalasia is a barium swallow study performed under fluoroscopic guidance.

A diagnosis of achalasia supported by the results of radiologic studies must always be confirmed by performing upper gastrointestinal endoscopy and esophageal manometry. These tests allow the direct evaluation and inspection of the esophageal mucosa and an objective measurement of esophageal contractility.

Endoscopy, supplemented by biopsy when necessary, helps in excluding gastroesophageal malignancies, fungal or bacterial infections, and other disease processes that can mimic achalasia.

Manometry must be considered the criterion standard for diagnosis of the disease. Manometric findings consistent with achalasia include incomplete LES relaxation, which is present in more than 80% of patients; elevated LES pressure, which is present in some patients; and diminished-to-absent peristalsis in the distal esophagus.

If manometric findings are normal in a patient with clinical symptoms or radiographic evidence of achalasia, a condition termed pseudoachalasia may be present. Causes of pseudoachalasia include esophageal and gastric malignancies and other tumors involving distal esophagus or LES. In patients with these conditions, endoscopy with biopsy analysis and CT can be helpful.

Limitations of Techniques

A fluoroscopically guided barium swallow study that demonstrates 1 or more findings (see Radiograph) is highly suggestive of achalasia. However, a definitive diagnosis can be made only by means of esophageal manometry, preferably with the addition of upper endoscopy.

Conversely, normal findings on barium swallow study do not completely exclude achalasia, especially in its early stages. This situation is when esophageal manometry is most valuable, because the physiologic derangements associated with achalasia precede the development of the anatomic findings discernible by using radiographic studies.

DIFFERENTIALS

Section 3 of 12  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Other Problems to be Considered

Amyloidosis
Chagas disease
Collagen-vascular disease
Lymphoma
Pseudoachalasia
Presbyesophagus
Diffuse esophageal spasm
Esophageal candidiasis
Diabetes mellitus

RADIOGRAPH

Section 4 of 12  

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• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Angiography
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• Multimedia
• References

Findings

Plain chest radiographs occasionally offer clues in the diagnosis of achalasia. A double mediastinal stripe is occasionally depicted. An air-fluid level can be seen in the esophagus; this is frequently retrocardiac. Owing to the paucity of air progressing through the hypertensive LES, the gastric air bubble may be small or absent.

Features of achalasia depicted at barium study under fluoroscopic guidance include the following:

• Failure of peristalsis to clear the esophagus of barium with the patient in the recumbent position
• Antegrade and retrograde motion of barium in the esophagus secondary to uncoordinated, nonpropulsive, tertiary contractions
• Pooling or stasis of barium in the esophagus when the esophagus has become atonic or noncontractile (which occurs late in the course of disease)
• LES relaxation that is incomplete and not coordinated with esophageal contraction
• Dilation of the esophageal body, which is typically maximal in the distal esophagus
• Tapering of the barium column at the unrelaxed LES, resulting in the bird beak sign
• Associated epiphrenic diverticula (possible finding)

According to Schima and coworkers, approximately 90% of patients undergoing barium swallow examination for suspected achalasia have some esophageal dilation and a classic bird beak deformity (Schima, 1992).

A recent study from El-Takli and colleagues (2006) contradicts this claim. These investigators reviewed the barium-contrast radiographs of 51 patients with manometrically diagnosed achalasia. In only 58% of these studies was achalasia mentioned as a diagnostic possibility by the interpreting radiologist. The radiographs were then provided to an expert gastrointestinal radiologist, mixed in with normal control studies. This expert determined that typical radiological features of achalasia were absent in 50% of the studies performed on achalasia patients. The authors concluded that barium-contrast radiography is not sensitive for the diagnosis of achalasia, frequently due to the lack of characteristic and detectable radiologic features.

Kostic and coinvestigators (2005) published preliminary data on timed barium esophagograms in patients with achalasia and in normal controls. Subjects were fasted and then given 250 mL of low-density barium sulfate suspension orally. Radiographs were made 1, 2, and 5 minutes after the start of barium administration. The height and width of the barium column and the rate of change over time were recorded. The study was repeated in all subjects after an approximate 1-week interval. The controls uniformly achieved complete esophageal emptying within 2 minutes. The height and width of the barium column and the rate of esophageal emptying were all markedly abnormal in the achalasia patients. The static data were very reproducible between studies, but the functional (esophageal emptying) data were not, with a coefficient of correlation of only 0.50. The authors concluded that further studies were necessary before clinical usefulness of the timed barium esophagograms could be confirmed.

Degree of Confidence

Chest radiographic findings have low sensitivity and specificity for the diagnosis of achalasia. If suspected, achalasia should be confirmed with other radiologic examinations, such as barium swallow study under fluoroscopy, and with upper gastrointestinal endoscopy and manometry.

False Positives/Negatives

No normal variants exist; however, several disease processes can mimic achalasia on chest radiographs or barium swallow studies. These include colon adenocarcinoma, esophageal carcinoma, gastric carcinoma, non–small cell lung cancer, thoracic scleroderma, amyloidosis, Chagas disease, collagen-vascular disease, and lymphoma.

According to Gockel and colleagues (2005), pseudoachalasia, caused by carcinomas and other disease processes or iatrogenic conditions involving the cardia and gastroesophageal junction, may be difficult to differentiate from achalasia. Pseudoachalasia may be indistinguishable from achalasia when conventional endoscopic, manometric, and radiologic diagnostic means are used. In their report, they described that pseudoachalasia was caused by primary malignancies in 53.9%, secondary malignancies in 14.9%, and benign lesions in 12.6% of the 264 cases in the series. The remainder of the cases (11.9%) were due to sequelae of operations involving the distal esophagus or proximal stomach.

Esophageal motor abnormalities can result from tumor infiltration of the esophageal wall and associated nerve damage. If mucosal irregularity or mass effect is present at the tapered gastroesophageal junction, pseudoachalasia should be considered. The use of amyl nitrite can often be helpful, as the LES relaxes in achalasia but remains fixed in pseudoachalasia.

CT SCAN

Section 5 of 12  

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• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

CT scanning with oral contrast enhancement may demonstrate the gross structural esophageal abnormalities associated with achalasia, especially dilatation, which is seen in advanced stages. However, CT findings are nonspecific, and the diagnosis of achalasia cannot be made using CT alone. CT scan may be indicated in the workup of patients with suspected pseudoachalasia.

Degree of Confidence

CT findings are nonspecific and insensitive in the early stages of achalasia. CT findings should always be confirmed by means of barium swallow study with fluoroscopy, upper gastrointestinal endoscopy, and esophageal manometry.

False Positives/Negatives

Disease processes that can mimic achalasia include colon adenocarcinoma, esophageal carcinoma, gastric carcinoma, non–small cell lung cancer, thoracic scleroderma, amyloidosis, Chagas disease, collagen-vascular disease, and lymphoma.

MRI

Section 6 of 12  

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• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

MRI studies are not indicated in the workup of patients with achalasia.

Degree of Confidence

MRI is not recommended in the diagnostic algorithm for achalasia.

ULTRASOUND

Section 7 of 12  

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• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

While ultrasound is not useful in establishing the primary diagnosis of achalasia, a recent study investigated its utility as a tool in the differentiation of true achalasia from pseudoachalasia.

Eckardt and coinvestigators (2004) performed transabdominal ultrasonography in subjects with achalasia (n = 28), in those with pseudoachalasia (ie, neoplasms of the gastric cardia, n = 13), and in 28 age- and sex-matched controls. The images were interpreted by a blinded observer. Achalasia patients could be discriminated from normal controls on the basis of a dilated esophagus without the presence of a neoplastic lesion. The median maximum esophageal diameter in achalasia patients was 20 mm, compared with 10.1 mm in controls (P <.001). Pseudoachalasia appeared as a hypoechoic lesion at the gastric cardia. Sensitivity and specificity rates for the diagnosis of pseudoachalasia were 100% and 82%, respectively.

Mittal (2005) reported on the utility of high-frequency intraluminal esophageal ultrasound in various esophageal motor disorders, including achalasia, diffuse esophageal spasm, and nutcracker esophagus. Hypertrophy and asynchrony of the longitudinal and circular muscle layers can be identified. Sustained contraction of the longitudinal muscle layer has been shown to correlate with symptoms such as chest pain and heartburn. This technique is not yet prevalent in clinical practice.

Degree of Confidence

Ultrasonography is not recommended for the primary diagnosis of achalasia at this time. As described above, it may prove useful as a screening test to discern achalasia from pseudoachalasia.

NUCLEAR MEDICINE

Section 8 of 12  

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• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

No nuclear medicine studies are commonly used in the diagnosis of achalasia.

Degree of Confidence

Nuclear medicine studies are not recommended for diagnostic purposes in achalasia.

ANGIOGRAPHY

Section 9 of 12  

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• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Findings

Angiography is not used for the diagnosis of achalasia.

Degree of Confidence

Angiography is not part of the diagnostic armamentarium for achalasia.

INTERVENTION

Section 10 of 12  

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• Ultrasound
• Nuclear Medicine
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• Intervention
• Multimedia
• References

No radiologic interventions are currently indicated for achalasia.

Treatment options for achalasia include pharmacologic, mechanical, botulinum toxin, and surgical-based therapies.

Pharmacologic therapy for achalasia relies on agents that relax the smooth muscle of the distal esophagus and LES. Four main classes of drugs have been used for this purpose and include the following:

• Calcium channel blockers - Nifedipine and verapamil
• Anticholinergic agents - Cimetropium bromide
• Nitrates - Isosorbide dinitrate
• Opioids - Loperamide

These agents all have demonstrated effectiveness in decreasing LES pressure in patients with achalasia; however, they frequently fail to relieve symptoms, or they are associated with significant adverse effects. For many patients, the effectiveness is only transient.

Mechanical therapy for achalasia consists of esophageal dilation, the object of which is to disrupt muscle fibers of the LES, effecting a decrease in LES pressure. Dilation is most commonly performed by using pneumatic balloons. The therapy is successful in decreasing LES pressure in 60-80% of patients; however, this change does not always translate into the relief or improvement of symptoms. Approximately one half of patients experience recurrent symptoms within 5 years. In most of these patients, the disease responds well to repeated dilation therapy. Long-term results do not appear to be as durable as results achieved with surgical esophageal myotomy.

Botulinum toxin therapy works by inhibiting the release of acetylcholine from presynaptic nerve terminals. An endoscopist injects botulinum toxin into the LES. The use of botulinum toxin has a good therapeutic index, but reports of few long-term studies have been published. As many as 33% of patients treated with botulinum toxin do not realize any benefit.

Esophageal (Heller) myotomy is a surgical procedure that is now commonly performed with minimally invasive techniques. The laparoscopic approach appears to be most appropriate. The results are as durable as those with an open approach and, according to Ancona and colleagues, laparoscopic surgery is associated with shorter recovery periods and more rapid discharge from the hospital (Ancona, 1995). Laparoscopy offers the surgeon the opportunity to perform an antireflux operation, whereas thoracoscopy does not.

Several series of laparoscopic esophageal myotomy with concomitant partial fundoplication have been reported. Good-to-excellent results have been achieved in 88% of patients, according to Hunter et al (Hunter, 1997) and in 98% of patients according to Rosati (Rosati, 1998).

Gaissert and colleagues (2006) published their series of patients treated with transthoracic Heller myotomy (n = 64 from 1962-1999. They demonstrated good early results in 91% of patients. In patients undergoing long-term follow-up, results described as good to excellent decreased to 63% (P <.0005). Earlt postoperative recurrence of symptoms was a significant factor portending less than satisfactory long-term results (P <.001).

Torquati and coworkers (2006) described their results in 200 consecutive patients with achalasia treated by laparoscopic Heller myotomy. The primary endpoint was the change in the patient's dysphagia score. Excellent relief was afforded to 85% of the study population. The strongest predictor of a good postoperative outcome was a high preoperative LES pressure. Patients with a preoperative LES pressure greater than 35 mm Hg were much more likely to attain excellent postoperative dysphagia relief (P = .0001).

Csendes and coinvestigators (2006) reported very long-term follow-up data on a cohort of 67 patients who had undergone Heller myotomy plus Dor fundoplication for achalasia. Patients were divided into 3 groups based on duration of follow-up: group I (80-119 m, n = 15), group II (120-239 mo, n = 35), and group III (>240 mo, n = 17).

Three patients developed squamous cell esophageal carcinomas within 15 years of surgery. Nine developed Barrett esophagus with up to 30 years of follow-up. A progressive deterioration in esophageal mucosa was noted. LES pressure remained low. Esophageal peristaltic activity was not improved. Acid reflux, as determined by 24-hour pH monitoring, tended to increase with time. The authors stated that good-to-excellent results persisted in 73% of the study group. Carcinoma had developed in 4.5%. They conceded treatment failures over the long term in the remaining 22.4%, citing reflux esophagitis as the main reason for failure. In their conclusion, the authors stated that initially good clinical surgical results progressively deteriorated with time. This deterioration is mainly due to an increase in esophageal acid exposure, with development of significant reflux esophagitis and Barrett esophagus.

Medical/Legal Pitfalls

• Radiologic features of achalasia may be obvious, or they may be difficult to demonstrate, especially early in the disease process.
• Regardless, if achalasia is clinically or radiologically suspected, the diagnosis must be confirmed by means of esophageal manometry.
• Upper endoscopy with an analysis of biopsy specimens may also be indicated.

MULTIMEDIA

Section 11 of 12  

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

Media file 1:  Barium swallow study demonstrating characteristics of achalasia, including the bird's beak deformity and a dilated esophagus.
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Media file 2:  Lateral view from a barium swallow study demonstrating a dilated esophagus.
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Media type:  X-RAY

Media file 3:  Detail of a barium swallow study demonstrating the classic bird's beak deformity of the distal esophagus.
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Media type:  X-RAY

REFERENCES

Section 12 of 12

• Authors and Editors
• Introduction
• Differentials
• Radiograph
• CT SCAN
• Mri
• Ultrasound
• Nuclear Medicine
• Angiography
• Intervention
• Multimedia
• References

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• Mittal RK. Motor and sensory function of the esophagus: revelations through ultrasound imaging. J Clin Gastroenterol. Apr 2005;39(4 Suppl 2):S42-8.
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Article Last Updated: Jun 22, 2006