Abnormal Propulsion of Food
The movement of food from mouth to stomach requires normal and coordinated action of the mouth and throat, propulsive waves of the esophagus, and relaxation of the sphincters. A problem with any of these functions can cause difficulty swallowing (dysphagia), regurgitation, vomiting, or aspiration of food (sucking food into the airways when inhaling).
Propulsion Disorders of the Throat
Propulsion disorders of the throat can cause trouble moving food from the upper part of the throat into the esophagus. Such problems occur most often in people who have disorders of the throat muscles or the nerves that serve them. The most common cause is stroke. Dermatomyositis, scleroderma, myasthenia gravis, muscular dystrophy, polio, pseudobulbar palsy, Parkinson's disease, and amyotrophic lateral sclerosis (Lou Gehrig's disease) all can affect the throat muscles or nerves. Difficulty swallowing may also result from the use of a phenothiazine (a class of antipsychotic drug), because these drugs can impair the normal function of the throat muscles. A person with a propulsion disorder of the throat often regurgitates food through the back of the nose or inhales it into the windpipe (trachea) and then coughs.
In cricopharyngeal incoordination, the upper esophageal sphincter (cricopharyngeal muscle) remains closed, or it opens in an uncoordinated way. An abnormally functioning sphincter may allow food to repeatedly enter the windpipe and lungs, which may lead to recurring lung infections and eventually to chronic lung disease. A surgeon can cut the sphincter so that it is permanently relaxed. If left untreated, the condition may lead to the formation of a diverticulum, a sac formed when the lining of the esophagus pushes outward and backward through the cricopharyngeal muscle.
Esophageal Spasm
Esophageal spasm (rosary bead or corkscrew esophagus) is a disorder of the propulsive movements (peristalsis) of the esophagus caused by malfunctioning nerves.
In this disorder, the normal propulsive contractions that move food through the esophagus are replaced periodically by nonpropulsive contractions. In addition, in 30% of people with this disorder, the lower esophageal sphincter opens and closes abnormally.
Symptoms
Muscle spasms throughout the esophagus typically are felt as chest pain under the breastbone coinciding with difficulty in swallowing liquids (especially those that are very hot or cold) or solids. Pain also occurs at night and may be severe enough to awaken a person. Esophageal spasm also may produce severe pain without swallowing difficulty. This pain, often described as a squeezing pain under the breastbone, may accompany exercise or exertion, making it difficult for a doctor to distinguish it from angina (chest pain stemming from heart disease). Over many years, this disorder may evolve into achalasia, a disorder in which the rhythmic contractions of the esophagus are greatly decreased.
Diagnosis
X-rays taken while the person swallows a barium drink may show that food does not move normally down the esophagus and that contractions of the esophageal wall are uncoordinated and do not propel the food. Esophageal scintigraphy (an imaging test that shows the movement of food that has been labeled or tagged with a tiny amount of radioactive tracer) is used to detect abnormal movements of food through the esophagus. Pressure measurements by manometry (a test in which a tube placed in the esophagus measures the pressure of contractions) (see Section 9, Chapter 119) provide the most sensitive and detailed analysis of the spasms. If these studies are inconclusive, a doctor may conduct manometry after the person eats a meal or takes a drug called edrophonium to provoke the painful spasms.
Treatment
Esophageal spasm is often difficult to treat. Nitroglycerin, long-acting nitrates, anticholinergics such as dicyclomine, or calcium channel blockers such as nifedipine may relieve the symptoms by relaxing the muscles of the esophagus. Sometimes, strong analgesics are needed. In many cases, a narrowing is treated by inflating a balloon inside the esophagus or by inserting bougies (progressively larger dilators) to dilate the esophagus. In rare cases, a surgeon must cut the muscle layer along the full length of the esophagus if other less radical forms of treatment are not effective.
Achalasia
Achalasia (cardiospasm, esophageal aperistalsis, megaesophagus) is a disorder in which the rhythmic contractions of the esophagus are greatly decreased and the lower esophageal sphincter fails to relax normally.
Achalasia results from a malfunction of the nerves controlling the rhythmic contractions of the esophagus. The cause of the nerve malfunction is not known.
Symptoms
Achalasia may occur at any age but usually begins, almost unnoticed, between the ages of 20 and 60 and then progresses gradually over many months or years. The tight lower esophageal sphincter causes the part of the esophagus above it to enlarge greatly. This enlargement contributes to many of the symptoms. Difficulty swallowing both solids and liquids is the main symptom. Other symptoms may include chest pain, regurgitation of the bland, nonacidic contents of the enlarged esophagus, and coughing at night. Although uncommon, chest pain may occur during swallowing or for no apparent reason. About one third of people who have achalasia regurgitate undigested food while sleeping. They may inhale food into their lungs, which can cause coughing, a lung abscess, infection of the airways, bronchiectasis, or aspiration pneumonia.
Diagnosis
X-rays of the esophagus taken while the person is swallowing barium show an absence of peristalsis. The esophagus is widened, usually only moderately but occasionally to enormous proportions, but is narrow at the lower esophageal sphincter.
Esophagoscopy (an examination of the esophagus through a flexible viewing tube) (see Section 9, Chapter 119) shows widening of the esophagus but no obvious obstruction. A doctor performs a biopsy (removal of tissue samples for examination under a microscope) to make sure the symptoms are not caused by cancer at the lower end of the esophagus.
Treatment
The aim of treatment is to relieve symptoms by getting the lower esophageal sphincter to open more easily. Nitrates (for example, nitroglycerin placed under the tongue before meals) or calcium channel blockers (for example, nifedipine) may delay the need for dilation by helping to relax the sphincter.
Dilation widens the sphincter mechanically--for example, by inflating a large balloon inside it. This procedure helps about 70% of the time, but repeated dilations may be needed. In fewer than 5% of people with achalasia, the esophagus ruptures during the dilation procedure. Esophageal rupture leads to inflammation of the surrounding tissue (mediastinitis) and in rare cases is fatal if not treated appropriately. Immediate surgery is needed to close the rupture in the wall of the esophagus.
As an alternative to mechanical dilation, a doctor may inject botulinum toxin into the lower esophageal sphincter. This newer therapy is as effective as mechanical dilation with balloons. Thus far, this method appears to be more successful in providing sustained symptom relief to older people than to younger people, but the long-term effects are not fully known.
If dilation or botulinum toxin therapy does not work, surgery to cut the muscular fibers in the lower esophageal sphincter (myotomy) is usually performed. Surgery can be done laparoscopically (see Section 9, Chapter 119). This surgery is successful about 85% of the time. A procedure to prevent backflow of acid from the stomach (gastroesophageal reflux) is usually performed during the same surgery, but about 15% of people still experience episodic backflow of acid after surgery.
Esophageal Pouches
Esophageal pouches (diverticula) are abnormal protrusions from the esophagus that in rare cases cause swallowing difficulties.
There are three types of esophageal pouches: pharyngeal pouch or Zenker's diverticulum, midesophageal pouch or traction diverticulum, and epiphrenic pouch. Each has a different cause, but probably all are related to uncoordinated swallowing and muscle relaxation, as may occur in disorders such as esophageal spasm and achalasia.
A large pouch can fill with food that may be regurgitated later, when the person bends over or lies down. This may cause food to be inhaled into the lungs during sleep, resulting in aspiration pneumonia. Rarely, the pouch enlarges and causes swallowing difficulty.
A video x-ray or cineradiograph (an x-ray that produces a moving image as a person swallows barium) is used to diagnose a pouch.
Treatment is not usually needed. If symptoms are severe, however, the pouch can be removed surgically. When esophageal spasm or achalasia is present, treatment of sphincter tightness may be needed.
| 
