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Author: C.E. Pope ♦ Download Chapter ♦ Download Lecture Slides & Notes

E. Malfunctions

The relative simplicity of the structure and function of the esophagus enables one to predict types of difficulty encountered in disease.

1. Developmental Anomalies (for your eyes only; do not memorize)



Figure 5

At birth one may encounter difficulties attributable to defective intrauterine development of the esophagus and adjacent structures. Since the lungs and trachea appear as a bud from the primitive foregut, it would seem logical that failures in separation of the trachea from the esophagus or in canalization of the esophagus might lead to difficulties immediately after birth. In the most common developmental anomaly, the upper end of the esophagus ends in a blind sac and its lower portion connects with the trachea. Such infants are unable to swallow material without regurgitating it back into the pharynx and at times aspirating it into the lungs (Fig. 5A). Air fills the stomach and the small bowel via the lower esophageal connection with the trachea. In the next most common anomaly (Fig. 5B), the upper esophagus joins the trachea while the lower portion extends up from the stomach as a blind sac. Swallowed material enters the lungs directly, causing pneumonia, and no air is found in the stomach or small bowel. Finally, both the esophagus and the trachea can be connected by an anomalous fistulous passage even though the trachea and esophagus are intact in their structure (Fig. 5C). If the infant is to survive such abnormalities, early diagnosis and surgical repair are essential.

2. Gastroesophageal Reflux Disease



GERD, definitions of esophagitis 		The term “reflux esophagitis” should be replaced by “gastroesophageal reflux disease” (GERD) as the term "esophagitis" is used with widely different meanings. To the clinician, reflux esophagitis may refer to the symptoms caused by the effect of material irritating the esophageal mucosa. The endoscopist uses the term to signify gross changes seen through the endoscope (a device used to inspect the lining of the GI tract). The pathologist may use it to mean histological changes seen on an esophageal biopsy. Unfortunately, these different ways of looking at the esophageal response to regurgitation of gastric contents do not always agree.


Heartburn 		What symptoms are caused by injury to the esophageal lining? The most common one is "heartburn". Heartburn is a term often used by patients to mean many different sensations. It is desirable for the patient and physician to agree on the definition of this term. By heartburn we mean a substernal burning sensation tending to radiate up into the neck; it often comes in waves and, except in its most extreme forms, is perceived as a burning rather than a painful sensation. Heartburn is often exaggerated by assuming positions which promote gastroesophageal regurgitation, such as bending over or lying supine (on one's back). Heartburn often occurs during pregnancy; the symptom vanishes after delivery, only to recur during subsequent pregnancies. Heartburn may be accompanied by esophageal regurgitation (the passage of fluid into the mouth from the stomach without the propulsive aid of vomiting) or by eructation (burping). Heartburn is felt in the midline of the chest and not under the left breast where most people believe their hearts to lie. It is often relieved by assuming the upright position, by taking antacids, or by ingesting a fair volume of water.

Mechanisms producing heartburn The actual mechanism of the production of heartburn is not clear. Whether this is the result of direct chemical irritation of nerve endings in the lamina propria beneath the squamous epithelium or whether it results from stimulation of abnormal esophageal muscle contractions has been a question. While motor abnormalities may coexist with severe heartburn, the sensation of heartburn is usually present when no abnormal esophageal motor activity is being recorded.

Consequences of acid/ pepsin contacting subepithelium


Esophageal bleeding 		Unfortunately, the lining of the esophagus is more sensitive to the action of acid and pepsin than is the lining of the stomach, small bowel, or colon. When squamous epithelial breakdown allows acid, pepsin, or other agents to gain access to the underlying tissues, certain consequences can be predicted. Bleeding is frequent because the esophagus is an extremely vascular organ with capillaries extending into the dermal papillae of the stratified squamous epithelium. Hematemesis (vomiting of blood) or melena (stools colored black by altered blood) may occur. Most patients who bleed from reflux esophagitis have heartburn, but inexplicably some do not.

Possible to have reflux esophagitis without pyrosis














Concept of acid clearance




Determinants of damage due to reflux:


Contact time
type of fluid
refluxed
esophageal emptying
ability
amount of saliva
mucosal resistance 		Reflux of gastric contents into the esophagus occurs in all of us. Studies using the impedance technique described earlier show that normal individuals have approximately 45 episodes of reflux per 24 hours, 60% of which are below pH 4. These episodes occur during transient lower esophageal sphincter relaxations (tLESR), although not every tLESR is accompanied by reflux. Patients with heartburn and/or histologic signs of reflux. Patients with heartburn and/or histologic signs of reflux will have increased numbers of reflux episodes. These episodes occur not only during tLESRs (the most common situation) but also when a weak sphincter is stressed by a sudden increase in abdominal pressure (lifting, coughing) or when the LES tone is so diminished that fluid can leak through the sphincter.

Patients with GERD will have not only more episodes of reflux but many of the episodes will be prolonged because of a failure of acid clearance. Acid clearance of the esophageal body occurs in several stages. The majority of the refluxed acid is returned to the stomach by a swallow-induced peristaltic wave. Several subsequent swallows of saliva containing bicarbonate neutralize the thin film of remaining acid adhering to the esophageal lining. Contact time of refluxed material is one of the factors that determine whether the patient will have damage due to reflux; other determinants are the type of fluid refluxed (the combination of acid and bile salts is more injurious than either alone), the ability of the esophagus to empty itself of refluxed material (secondary peristalsis), the amount of neutralizing saliva produced, the inherent resistance of the esophageal mucosa to digestion, and undoubtedly other factors as well.

Events occurring during sleep may also affect the prevalence and consequences of gastroesophageal reflux. Intuitively, the sleeping position would remove the protective effect of gravity enjoyed by those in the upright position. Studies have also shown that the upper esophageal sphincter tends to maintain a lower resting pressure during sleep, and primary peristalsis (the major method of clearing refluxed material) is inhibited during deep sleep. Fortunately, tLESRs are uncommon during sleep. When actually measured by pH studies, nocturnal reflux is relatively uncommon in those complaining of daytime reflux symptoms. It can also be shown that reflux episodes are associated with episodes of arousal that can permit primary peristalsis to clear the refluxed material. Unfortunately, these periods of arousal impair the quality of sleep, leading to a grouchy patient!



Sliding Hiatal Hernia
Figure 6A

Role of hiatal hernia Historically speaking, reflux and reflux esophagitis have been equated with the presence of a sliding hiatal hernia. (Fig 6A) A sliding hiatal hernia forms when the phrenoesophageal ligament becomes lax and allows the lower esophageal sphincter and a portion of stomach to slide up into the mediastinum. When a large portion of the stomach is in the thoracic cavity, it is easy to be certain that a sliding hiatal hernia exists. There is much disagreement about small hernias because neither the position of the diaphragmatic hiatus nor the junction between esophagus and stomach can be unequivocally defined. Although reflux and the presence of a hernia may be associated, either can be present without the other. It is reflux, the physiologic event, which should receive diagnostic and therapeutic attention. The hiatal hernia may be important in the pathogenesis of GERD because acid, trapped in the pouch of the hernia, may be refluxed when the lower esophageal sphincter undergoes a transient relaxation.



Paraesophageal Hernia
Figure 6B

A less common type of hernia is the paraesophageal hernia. (Fig 6B) In this condition, the gastroesophageal junction usually remains below the diaphragm, but the fundus, antrum or rarely the entire stomach herniates up into the mediastinum. Such a condition can remain without symptoms and is discovered during a routine chest film taken for other reasons. Occasionally erosions form in the herniated stomach and the patient presents with gastrointestinal bleeding. If the stomach twists upon itself (torsion), it may end up with a compromised blood supply and present with severe pain and shock. Most surgeons feel that a symptomatic paraesophageal hernia should be corrected surgically.

Inflamed esophagus may resolve or lead to scarring, stricture, and dysphagia







Usually, stricture causes dysphagia with solids and not liquids 		Acid-peptic digestion, corrosive chemicals, or thermal injury to the deeper esophageal layers cause inflammation followed by repair which may restore the esophagus or go on to scarring and stricture (permanent narrowing) formation. Stricture causes dysphagia (swallowing difficulty) which is one of the most significant esophageal symptoms. Dysphagia is most commonly described by patients as a sensation of food sticking, hesitating, or pausing at the level of obstruction, which is often localized accurately with a pointing finger. Dysphagia may or may not be associated with pain and may not be severe enough to prompt the patient to seek medical attention. Such a casual attitude should never be displayed by the physician because dysphagia is always a symptom of disease whether its basis is a structural alteration or a functional abnormality. Characteristically, an esophageal stricture causes dysphagia after swallowing solids such as meat or bread, but not after liquids. The patient with a stricture caused by reflux peptic esophagitis usually gives an antecedent history of heartburn.

Odynophagia = painful swallowing Another symptom which denotes either a mucosal lesion or a motor disorder is odynophagia, or pain upon swallowing. This may or may not accompany dysphagia, but points to the need for investigation of the esophagus.

If the refluxed material breeches the upper esophageal sphincter as well as the lower esophageal sphincter, then acid laryngitis may occur. The patient will present with a hoarse voice, frequent throat clearing or a persistent cough. Further extension of the refluxed material into the trachea or lungs may lead to attacks of wheezing. There are no current techniques which will allow a causal relationship between reflux and laryngeal or lung disease to be established. The best that can be done is a therapeutic trial of antireflux therapy.

Some patients with severe reflux will replace a portion of the squamous epithelium of the esophagus with a metaplastic, columnar epithelium (Barrett's esophagus). This probably occurs when there is confluent deep ulceration which is constantly bathed with refluxed stomach contents containing acid and bile salts. Most commonly, it begins at the gastroesophageal junction and extends proximally for a variable length. It can also occur as isolated islands. It can usually be recognized endoscopically by its velvety red color. Histologically, it is characterized by a columnar epithelium containing goblet cells. Once present, the metaplastic epithelium can further change and develop dysplasia and then adenocarcinoma. Changes in DNA content and aneuploidy precede the change to cancer and allow the possibility of screening for precancerous changes.

3. Carcinoma of the Esophagus

The mucosa of the esophagus can give rise to both squamous cell carcinoma and to adenocarcinoma. Squamous cell carcinoma of the esophagus is very common in certain areas of the world (Iran, China, South Africa); in the United States it is found most often in smokers and alcoholics.

Adenocarcinoma associated with Barrett’s epithelium





Dysphagia must be evaluated 		Adenocarcinoma can occur primarily in the esophagus, arising either from glandular rests in the epithelium, or from epithelium that has undergone metaplastic changes from reflux (Barrett's epithelium). This latter tumor is unfortunately becoming much more common, especially in white males. Tumors are usually not found incidentally and make their appearance known by causing dysphagia. In order to cause dysphagia, the growth has usually involved at least 2/3 of the circumference of the esophagus. The advanced size that the carcinomas attain before producing symptoms militates against early recognition and cure. However, there is often a delay after onset of symptoms before definitive diagnosis. The responsibility for this delay is often shared by the patient who does not seek early help and the physician who may ignore or fail to investigate fully the symptom of dysphagia. A good rule is that dysphagia appearing in a patient over 40 is due to carcinoma until proven otherwise..

Tumors invade locally; can spread by lymph or blood Dysphagia usually increases as the tumor grows; the tumor may produce total esophageal obstruction and secondary pulmonary aspiration. The tumor may extend and involve the trachea with production of a tracheo-esophageal fistula. The tumor may also spread either locally in the mediastinum or via the lymphatics and blood stream to the liver. A search for metastases (spread of tumor) is always necessary in the pretreatment evaluation of carcinoma of the esophagus. Sometimes the differential diagnosis between carcinoma of the esophagus and stricture due to reflux esophagitis is difficult.

4. Motility Disorders

Caused by muscle or coordination disorder

Dysphagia with solids and liquids

Cricopharyngeal disorder → aspiration 		If the muscle of the esophagus is affected by disease processes, or if the coordinating mechanisms of the esophagus are disturbed, fluid retention within the body of the esophagus can lead to regurgitation. If the cricopharyngeal area is involved, as is seen in polymyositis or central nervous system disturbances, then aspiration of liquid into the trachea can occur. Usually, dysphagia from motor disorders of the esophageal body is intermittent, is caused by liquids as well as solids, and can be relieved by positional changes, a Valsalva maneuver, or by "washing down" a solid bolus with fluid.

a. Achalasia

LES fails to relax The most thoroughly understood motility disorder of the esophagus is achalasia. Classic achalasia is manifested by a dilated esophagus with absent peristalsis in the smooth muscle part of the esophagus. The lower esophageal sphincter relaxes either not at all or only partially in response to a swallow, so that food and fluid remains in the esophagus until the hydrostatic pressure of the retained column of fluid is high enough to force material through the sphincter. Retention of this material in the esophagus may also lead to nocturnal aspiration - so that achalasia may present as a primary lung disease.

Pathology is in the myenteric plexus Pathologic examination of the esophageal wall in many cases of achalasia will show infiltration of Auerbach's plexus with round cells, or fibrosis of Auerbach's plexus with absent ganglion cells. The failure of LES relaxation is thought to be due to drop-out of nerves which contain inhibitory neurotransmitters such as nitric oxide. Therefore, the excitatory nerves in the sphincter are unopposed leading to a high resting pressure and a failure of relaxation.

It is becoming clear that there are other motor disorders of the esophagus which clinically resemble achalasia, but lack some of the manometric features of the classic disease such as aperistalsis or decreased sphincter relaxation. Other patients show rhythmic contractions of the esophageal body not related to swallowing. Still others show very strong prolonged contractions which can be associated with chest pain and/or dysphagia.

b. Diffuse Spasm

Diffuse spasm (if strictly defined) is a much more uncommon illness. Some swallows cause a peristaltic wave, but other swallows cause simultaneous contractions of the esophageal body which may produce chest pain with radiation through to the back. In addition, dysphagia may be present during these episodes of contraction. X-ray may show a series of sacculations of the esophagus. The pain of diffuse spasm may be very severe, is often confused with angina pectoris, and is sometimes brought on by ingesting cold liquids.

There also exist other less well characterized motor disorders with some of the clinical and manometric features mentioned above, but lacking enough features to make a diagnosis of achalasia or diffuse spasm. Probably these two disorders are only part of a much wider spectrum.


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