Gastroparesis is a condition in which the muscles in your stomach don't function normally.

Ordinarily, strong muscular contractions propel food through your digestive tract. But in gastroparesis, the muscles in the wall of your stomach work poorly or not at all, preventing your stomach from emptying properly. This can interfere with digestion, cause nausea and vomiting, and play havoc with blood sugar levels and nutrition.

No available treatment can cure gastroparesis. Dietary changes and certain medications sometimes help control symptoms of gastroparesis, but they're not effective in every case. And the available gastroparesis drugs can cause serious side effects. Researchers are investigating other types of therapies for gastroparesis.

The most common gastroparesis symptoms are:

• Nausea
• Vomiting
• A feeling of fullness after eating just a few bites (early satiety)

Vomiting usually occurs several hours after you've eaten when your stomach is still full of undigested food and normal stomach secretions. Sometimes, accumulated stomach enzymes and acids can cause vomiting even if you don't eat. And because different stomach muscles empty solid food and liquids, you may have problems with solids only, with both solids and liquids, or, in rare cases, with liquids alone.

In addition to nausea, vomiting and premature fullness, gastroparesis often causes:

• Abdominal bloating
• Heartburn or gastroesophageal reflux
• Changes in blood sugar levels
• Lack of appetite
• Weight loss and malnutrition

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Stomach

Your stomach is a muscular sac located in the upper middle of your abdomen, just below your ribs. If you're an average adult, it's about the size of a small melon, but can stretch to hold nearly 1 gallon of food and liquid. Your stomach folds in on itself when it's empty and expands when you eat or drink.

The walls of your stomach are lined with three layers of powerful muscles that mix food with enzymes and acids produced by glands in your stomach's inner lining. Once the food is thoroughly pulverized — reduced to the consistency of porridge — strong muscular contractions (peristaltic waves) push it toward the pyloric valve, which leads to the upper portion of your small intestine (duodenum), where the real work of digestion takes place. The valve opens just enough to release a scant eighth of an ounce of food at a time.

It may take three to four hours for your stomach to empty after you eat, depending on your diet — foods high in fat can prolong the emptying time considerably. The slowness of the process ensures that food is thoroughly mixed with digestive juices for the best possible absorption.

Why the stomach stops working
Arguably the most important nerve in your body, the vagus nerve stretches from your brainstem to your colon. It helps orchestrate the complex microcircuits in your digestive tract, including signaling the smooth muscles in your stomach to contract in peristaltic waves — usually at the rate of about three contractions a minute. When these contractions slow or stop completely, food doesn't move out of your stomach into the duodenum as it should.

Damage to the vagus nerve is the leading cause of gastroparesis, although the disorder can also result from damage to the stomach muscles themselves. Factors that can damage nerves or muscles in your stomach include:

• Diabetes. Affecting people with either type 1 diabetes or type 2 diabetes, this is one of the most common causes of gastroparesis. Over time, high blood glucose levels and their metabolic effects can damage the vagus nerve and disrupt its normal functioning. Once gastroparesis develops, diabetes often becomes worse because erratic stomach emptying and poor absorption make blood sugar levels harder to control.
• Surgery. Operations involving your esophagus, stomach or upper part of your small intestine can injure the vagus nerve and lead to gastroparesis. Symptoms may develop immediately after the surgery or appear years later.
• Medications. Many commonly prescribed drugs slow stomach emptying. Chief among these are narcotic pain medications, tricyclic antidepressants and calcium channel blockers. Antacids that contain aluminum hydroxide, some high blood pressure medications and the psychiatric drug lithium also can disrupt the normal functioning of the stomach. Symptoms usually improve once you stop taking the medication.

• Cancer treatments. Nausea and vomiting are common side effects of chemotherapy because most anti-cancer drugs target fast-growing cells throughout your body, including healthy cells in your intestinal tract. The nausea and vomiting are usually temporary and improve when treatment ends.

  But some people receiving high doses of chemotherapy drugs may develop intractable nausea and vomiting as a result of chemotherapy-induced gastroparesis. In that case, problems with the stomach being able to move food (motility problems) originate in the nausea center of the brainstem, just above the spinal cord. Radiation therapy to the chest and abdomen also can cause gastroparesis.

• Other disorders. A number of other medical conditions can cause gastroparesis, including anorexia and bulimia, the connective tissue disease scleroderma, Parkinson's disease and other nervous system illnesses, and metabolic disorders such as hypothyroidism. For reasons that aren't clear, some otherwise healthy people develop gastroparesis after a bout of the flu or other viral illness.

Risk factors for gastroparesis include:

• Diabetes, which is the leading risk factor and with at least one in five people with diabetes eventually developing gastroparesis
• Taking medications that slow the rate of stomach emptying
• Having abdominal surgery
• Having certain cancer treatments
• Having another medical condition that can damage the stomach nerves or muscles

The most common signs and symptoms of gastroparesis — nausea, vomiting, bloating and a feeling of fullness early in a meal — occur now and then in almost everyone. In the great majority of cases, the cause is a problem other than gastroparesis. If you have an occasional bout of heartburn or nausea, you can probably treat it yourself by changing what or how much you eat or by using over-the-counter medications.

See your doctor if you have persistent digestive problems that don't improve with self-care measures.

Doctors use several tests to help diagnose gastroparesis. Some tests check specifically for signs of the disorder; others rule out conditions that cause similar symptoms. These tests include:

• Gastric emptying studies. Usually considered the most accurate way to diagnose gastroparesis, gastric emptying studies can take various forms.

  In the most common test, you eat a meal in which a solid food — often eggs or oatmeal — contains a small amount of radioactive material. A scanner, acting like a Geiger counter, is placed over your abdomen to monitor the rate at which food leaves your stomach.

  Other gastric emptying studies check how well your stomach muscles relax after you eat — poor muscle relaxation can produce the same signs and symptoms as delayed stomach emptying.

• Gastroduodenal manometry. In this test, your doctor threads a pressure-sensitive plastic tube down your throat and into your stomach and small intestine. The tube is connected to a computer that monitors the strength, frequency and coordination of muscle contractions before and after you eat. Gastroduodenal manometry can distinguish among different motility disorders, but it isn't available everywhere and usually isn't necessary to diagnose gastroparesis.
• Upper gastrointestinal (GI) endoscopy. Rather than helping diagnose gastroparesis, this test is used to rule out other conditions that can cause delayed gastric emptying. In an upper GI endoscopy, you swallow a tube with a tiny camera that allows your doctor to scan your stomach and small intestine for obstructions.
• Electrogastrogram. Electrical signals control the muscle contractions in your stomach, just as electrical impulses regulate your heartbeat. An electrogastrogram, an experimental procedure that's similar to an electrocardiogram (ECG), records the electrical signals in your stomach before and after you eat. In a normal stomach, the electrical rhythm is regular and speeds up after a meal, but in most people with gastroparesis, the rhythm is irregular, doesn't increase after eating or is nonexistent.
• Magnetic resonance imaging (MRI). This imaging technique uses a powerful magnet and radio waves to produce cross-sectional images of your body. It's used to diagnose a broad range of conditions, including various cancers, but researchers are also studying the use of real-time MRI to help evaluate stomach motility. Unlike other tests for gastroparesis, MRI isn't invasive and doesn't expose you to radiation.

Gastroparesis can cause several complications, such as:

• Weight loss and malnutrition. These problems can occur when delayed stomach emptying affects your body's ability to digest and absorb nutrients. Also contributing to poor absorption is bacterial overgrowth — the explosive growth of harmful microorganisms that normally inhabit the gut. These organisms usually are kept in check by beneficial bacteria, but fermenting food in the stomach disrupts the balance of good and bad bacteria.
• Bezoars. Undigested food in your stomach can harden into a bezoar, a solid mass that's similar to a hairball in a cat. Bezoars are likely to cause nausea and vomiting and may be life-threatening if they prevent food from passing into your small intestine.
• Blood sugar fluctuations. Although gastroparesis doesn't cause diabetes, inconsistent food absorption can cause erratic changes in blood sugar levels, which make diabetes worse. In turn, poor control of blood sugar levels makes gastroparesis worse.

Controlling diabetes or any other underlying condition that may be causing gastroparesis is the first step in treating the condition.

Beyond this, the mainstay of gastroparesis treatment has long involved:

• Dietary changes
• Medications that increase stomach contractions

Because the few drugs approved for the condition can have serious side effects and aren't always effective, doctors are also trying less conventional approaches.

A change in diet habits
Diet remains one of the cornerstones of gastroparesis treatment, and most doctors recommend specific dietary changes, including:

• Smaller, more frequent meals. Because a supersized meal takes longer to digest than a light snack, you're likely to do better eating six to eight small meals a day instead of two or three large ones. Smaller, more frequent meals also help avoid the feeling of fullness that plagues many people with gastroparesis.

  For people whose appetite wanes later in the day, dietitians suggest eating solid, nutrient-dense foods in the morning, then switching to lighter meals or liquids in the afternoon and evening. Some people are helped by lying on their right side after eating, which allows gravity to help empty the stomach. If you have diabetes, your doctor may recommend a liquid diet until your blood sugar is brought under control or the gastroparesis is better managed.

• Low-fiber foods. Fiber, found mainly in raw fruits and vegetables, whole grains, and legumes, helps whisk food through the intestinal tract. But fiber has the opposite effect in the stomach, which needs extra time and effort to break down roughage. Fibrous foods are also more likely to form bezoars than softer foods are.

  For these reasons, people with gastroparesis are usually advised to substitute low-fiber foods - well-cooked fruits and vegetables, fish, chicken, yogurt, and refined breads and grains — for fiber-rich fare. Foods particularly likely to cause bezoars include dried figs, berries of all kinds, apples, coconut, corn, brussels sprouts, and potato and tomato peels.

• Low-fat foods. Low-fat diets for people with gastroparesis are problematic. Although it's true that fat slows digestion — sometimes doubling the amount of time food remains in the stomach — some experts argue that people with gastroparesis need the calories and nutrients in high-fat liquids, such as milkshakes. As a general rule, doctors recommend avoiding fatty foods, but they may allow small servings of milkshakes or other rich drinks, especially between meals, for people who are able to tolerate them.
• Pureed and liquid foods. Many people with gastroparesis find that they do best with soups or pureed foods. Almost any food can be pureed, including cooked fruits and vegetables, poached or baked chicken and fish (add chicken or fish broth to achieve a workable consistency), cereals (blend with milk or rice milk for flavor and texture), and even pasta dishes.
• Nutritional supplements. Because gastroparesis interferes with digestion, people with the disorder may be deficient in important nutrients, including vitamin B-12, iron and calcium. A liquid vitamin and mineral supplement can help supply missing nutrients, but shouldn't be used as a substitute for meals.
• Water. The vomiting caused by gastroparesis can lead to dehydration, so it's especially important to drink plenty of water. Taking small sips or sucking on ice chips may make it easier to keep water down when you're nauseous.

• Feeding tube. Most people with gastroparesis do well eating pureed foods and using nutritional supplements. But some people with severe stomach problems may not be able to tolerate any food or liquids. In that case, doctors may place a feeding tube (jejunostomy tube) in the small intestine.

  The tube is usually inserted directly into your small intestine through your skin, although a temporary nasal or oral tube — the tube is threaded into the small intestine through your nose or mouth — is often tried first to make sure you can tolerate this type of feeding. The tube is usually temporary and is only used when gastroparesis is severe or when blood sugar levels can't be controlled by any other method.

Medications
Doctors usually prescribe two types of drugs to treat gastroparesis:

• Anti-emetics, such as prochlorperazine, which help control nausea and vomiting
• Prokinetics, which stimulate contractions of the stomach muscles

Because pills are often poorly absorbed, medications may be injected or given in a liquid form.

Prokinetic drugs
In the United States, drugs used to stimulate stomach contractions include:

• Metoclopramide. This prokinetic drug affects your stomach in several ways: It lowers the pressure threshold for the peristalsis reflex, it increases the strength and frequency of muscle contractions, and it relaxes the pyloric valve that releases food from the stomach into your small intestine. Metoclopramide also acts on the part of the brain that controls nausea and vomiting, helping relieve these symptoms in some people.

  But for all this, metoclopramide has serious drawbacks, including side effects such as agitation, depression, severe muscle twitching (tardive dyskinesia) and painful breast swelling in both men and women. It's not intended for long-term use. Domperidone, a drug that's similar to metoclopramide but without many of its side effects, is available in Canada and Europe.

• Erythromycin. This drug isn't a prokinetic; instead, it's a common antibiotic that produces short bursts of strong stomach contractions. The drawbacks: Most people develop a tolerance to the drug fairly quickly; it can cause nausea, vomiting, diarrhea and, in some cases, hearing loss; and it may have significant drug interactions. For these reasons, erythromycin is usually used only intermittently or when symptoms become worse.
• Cisapride. Commonly used to treat severe cases of gastroesophageal reflux, cisapride has been linked to fatal heart arrhythmias and is not appropriate for anyone with heart disease or kidney problems. Cisapride also has the potential to cause serious drug interactions. The drug has limited availability in the United States because of these risks.

Surgery
An operation may be an option when all other measures fail to provide relief from severe nausea and vomiting or malnutrition. In that case, the lower part of the stomach may be stapled or bypassed to help improve stomach emptying. This type of surgery can cause serious complications and is a treatment of last resort.

Emerging therapies
Although not usually life-threatening, gastroparesis can profoundly affect quality of life and make diabetes more difficult to control, which is why researchers are looking at better ways to manage it. Some emerging therapies include:

• Botulinum toxin (Botox). Once used exclusively to treat migraines and wrinkles, botulinum toxin is now being tried for a variety of problems, including gastroparesis. In trials, researchers have found that Botox relaxes the pyloric muscle in some people, thereby allowing the stomach to release more food. The benefits are temporary, however, and more studies are needed to determine the overall usefulness of this treatment.
• Electrical gastric stimulation. Another new treatment for gastroparesis uses an electric current to stimulate stomach contractions. Working much like a heart pacemaker, a stomach pacemaker, consisting of a tiny generator and two electrodes, is placed in a pocket that surgeons create on the stomach's outer edge. Stomach pacemakers have been shown to improve stomach emptying and reduce nausea and vomiting. It takes time for the pacemaker to produce these effects, however, and the procedure isn't widely available.

Because gastroparesis is most common in people with diabetes, controlling blood sugar levels is the best way to help prevent the disorder.