| 释义 |
achalasiaenUS
ach·a·la·sia A0052700 (ăk′ə-lā′zhə)n. The failure of a ring of muscle fibers, such as a sphincter of the esophagus, to relax.
[New Latin : a- + Greek khalasis, relaxation (from khalān, to loosen).]achalasia (ˌækəˈleɪzɪə) n (Medicine) pathol failure of the cardiac sphincter of the oesophagus to relax, resulting in difficulty in swallowing[New Latin, from a-1 + Greek chalasis relaxation]ach•a•la•sia (ˌæk əˈleɪ ʒə, -ʒi ə, -zi ə)
n. inability of a circular muscle, esp. of the esophagus or rectum, to relax, resulting in widening of the structure above the muscular constriction. [1910–15; a-6 + Greek chálas(is) (chala-, s. of chalân to loosen + -sis -sis) + -ia] TranslationsachalasiaenUS
achalasia[‚ak·ə′lāzh·ē·ə] (medicine) Inability of a hollow muscular organ or ring of muscle (sphincter) to relax. achalasiaenUS
Achalasia DefinitionAchalasia is a disorder of the esophagus that prevents normal swallowing.DescriptionAchalasia affects the esophagus, the tube that carries swallowed food from the back of the throat down into the stomach. A ring of muscle called the lower esophageal sphincter encircles the esophagus just above the entrance to the stomach. This sphincter muscle is normally contracted to close the esophagus. When the sphincter is closed, the contents of the stomach cannot flow back into the esophagus. Backward flow of stomach contents (reflux) can irritate and inflame the esophagus, causing symptoms such as heartburn. The act of swallowing causes a wave of esophageal contraction called peristalsis. Peristalsis pushes food along the esophagus. Normally, peristalsis causes the esophageal sphincter to relax and allow food into the stomach. In achalasia, which means "failure to relax," the esophageal sphincter remains contracted. Normal peristalsis is interrupted and food cannot enter the stomach.Causes and symptomsCausesAchalasia is caused by degeneration of the nerve cells that normally signal the brain to relax the esophageal sphincter. The ultimate cause of this degeneration is unknown. Autoimmune disease or hidden infection is suspected.SymptomsDysphagia, or difficulty swallowing, is the most common symptom of achalasia. The person with achalasia usually has trouble swallowing both liquid and solid foods, often feeling that food "gets stuck" on the way down. The person has chest pain that is often mistaken for angina pectoris (cardiac pain). Heartburn and difficulty belching are common. Symptoms usually get steadily worse. Other symptoms may include nighttime cough or recurrent pneumonia caused by food passing into the lower airways.DiagnosisDiagnosis of achalasia begins with a careful medical history. The history should focus on the timing of symptoms and on eliminating other medical conditions that may cause similar symptoms. Tests used to diagnose achalasia include:- Esophageal manometry. In this test, a thin tube is passed into the esophagus to measure the pressure exerted by the esophageal sphincter.
- X ray of the esophagus. Barium may be swallowed to act as a contrast agent. Barium reveals the outlines of the esophagus in greater detail and makes it easier to see its constriction at the sphincter.
- Endoscopy. In this test, a tube containing a lens and a light source is passed into the esophagus. Endoscopy is used to look directly at the surface of the esophagus. This test can also detect tumors that cause symptoms like those of achalasia. Cancer of the esophagus occurs as a complication of achalasia in 2-7% of patients.
TreatmentThe first-line treatment for achalasia is balloon dilation. In this procedure, an inflatable membrane or balloon is passed down the esophagus to the sphincter and inflated to force the sphincter open. Dilation is effective in about 70% of patients.Three other treatments are used for achalasia when balloon dilation is inappropriate or unacceptable.- Botulinum toxin injection. Injected into the sphincter, botulinum toxin paralyzes the muscle and allows it to relax. Symptoms usually return within one to two years.
- Esophagomyotomy. This surgical procedure cuts the sphincter muscle to allow the esophagus to open. Esophagomyotomy is becoming more popular with the development of techniques allowing very small abdominal incisions.
- Drug therapy. Nifedipine, a calcium-channel blocker, reduces muscle contraction. Taken daily, this drug provides relief for about two-thirds of patients for as long as two years.
PrognosisMost patients with achalasia can be treated effectively. Achalasia does not reduce life expectancy unless esophageal carcinoma develops.PreventionThere is no known way to prevent achalasia.ResourcesBooksGrendell, James H., Kenneth R. McQuaid, and Scott L. Friedman, editors. Current Diagnosis and Treatment in Gastroenterology. Stamford: Appleton & Lange, 1996.Key termsBotulinum toxin — Any of a group of potent bacterial toxins or poisons produced by different strains of the bacterium Clostridium botulinum. The toxins cause muscle paralysis.Dysphagia — Difficulty in swallowing.Endoscopy — A test in which a viewing device and a light source are introduced into the esophagus by means of a flexible tube. Endoscopy permits visual inspection of the esophagus for abnormalities.Esophageal manometry — A test in which a thin tube is passed into the esophagus to measure the degree of pressure exerted by the muscles of the esophageal wall.Esophageal sphincter — A circular band of muscle that closes the last few centimeters of the esophagus and prevents the backward flow of stomach contents.Esophagomyotomy — A surgical incision through the muscular tissue of the esophagus.Esophagus — The muscular tube that leads from the back of the throat to the entrance of the stomach.Peristalsis — The coordinated, rhythmic wave of smooth muscle contraction that forces food through the digestive tract.Reflux — An abnormal backward or return flow of a fluid.achalasia [ak″ah-la´zhah] failure to relax of the smooth fibers" >muscle fibers of the gastrointestinal tract at any junction of one part with another. Especially failure of the lower esophagus to relax with swallowing, due to degeneration of ganglion cells in the wall of the organ. Achalasia. From Damjanov, 2000.
The cause is unknown, but anxiety and emotional tension seem to aggravate achalasia and precipitate attacks. As the condition progresses there is dilatation of the esophagus (megaesophagus) above the constriction and loss of peristalsis in the lower two-thirds of the organ.Symptoms. The patient complains of progressive dysphagia and a feeling of fullness in the sternal region; vomiting frequently occurs, and there may be aspiration of the esophageal contents into the respiratory passages. As a result of this aspiration the patient may develop pneumonia or atelectasis. Diagnosis is confirmed by manometric readings, which document motor dysfunction.Treatment. Conservative treatment of mild cases consists of advising the patient to eat a bland diet that is low in bulk. Very large meals should be avoided and all foods should be eaten slowly with frequent drinking of fluids during the meal. To reduce the possibility of aspiration of esophageal contents during sleep, the patient is instructed to sleep with the head and shoulders elevated.
A nonsurgical method for treating resistant cases is repeated dilation of the esophageal sphincter by means of a bougie or by a pneumatic bag that is guided into place under x-ray visualization.
As a last resort surgical intervention may be necessary. An incision, which includes the lower esophagus and upper stomach wall, is made down to but not through the intestinal mucosa. This allows for stretching of the mucosa to accommodate food passing through. Approach is made through an incision into the chest; thus, preoperative care and postoperative care are the same as for elective chest surgery (see thoracic surgery).a·cha·la·si·a (ak-ă-lā'zē-ă), Failure to relax; referring especially to visceral openings such as the pylorus, cardia, or any other sphincter muscle. [G. a- priv. + chalasis, a slackening] achalasia (ăk′ə-lā′zhə)n. The failure of a ring of muscle fibers, such as a sphincter of the esophagus, to relax.achalasia A dysmotility disorder characterised by a loss of peristalsis in the distal 2⁄3 of the oesophagus accompanied by impaired relaxation of the lower oesophageal sphincter.
Aetiology
Idiopathic, possibly autoimmune; secondary to neoplasia, vagotomy, sarcoid, MEN2A.
Clinical findings
Dysphagia, chest pain, vomiting, heartburn.
Imaging
Plain films, air-fluid level in enlarged oesophagus, barium swallow, bird’s beak tapering and, if prolonged, sigmoid oesophagus.
DiffDx
Chaga’s disease, T-cruzi amastigotes.
Management
Pneumatic dilation of oesophagus; medication (e.g., nitroglycerin, CCBs (e.g., nifedipine); surgery (e.g., Heller myotomy). Short-term (maximum 12-month) response is achieved with intrasphincteric injection of botulinum toxin.achalasia GI disease An idiopathic dysmotility disorder, characterized by a loss of peristalsis in the distal 2⁄3 of the esophagus accompanied by impaired relaxation of the lower esophageal sphincter Clinical Dysphagia, chest pain, vomiting, heartburn Imaging Plain films, air-fluid level in an enlarged esophagus; barium swallow, bird's beak tapering and, if prolonged, sigmoid esophagus Management Pneumatic dilation of esophagus; medication–eg nitroglycerin, CCBs–eg, nifedipine; surgery–eg, Heller myotomy. See GERD. a·cha·la·si·a (ak-ă-lā'zē-ă) Failure to relax; referring especially to visceral openings such as the pylorus, cardia, or any other sphincter muscles. [G. a- priv. + chalasis, a slackening]achalasia Failure of a muscle ring (SPHINCTER) to relax when it should. Achalasia most commonly affects the sphincter at the bottom of the gullet (OESOPHAGUS). See also ACHALSIA OF THE CARDIA.a·cha·la·sia (ak-ă-lā'zē-ă) Failure to relax; referring especially to visceral openings. [G. a- priv. + chalasis, a slackening]ThesaurusSeecardiospasm |