Intestinal Gas (Belching, Bloating, Flatulence)

Intestinal gas facts

• The usual cause of belching is excessive gas in the stomach that comes from swallowed air. However, discomfort in the abdomen for any reason may also cause belching. Therefore, belching does not always indicate the presence of excessive gas in the stomach.
• Bloating is the subjective feeling that the abdomen is enlarged but does not necessarily mean that the abdomen is, in fact, enlarged. Distention is the objective enlargement of the abdomen.
• Continuous distention of the abdomen is usually caused by fluid, tumors, enlarged organs, or fat within the abdomen.
• Intermittent distention of the abdomen may be caused by excessive formation of intestinal gas, as well as physical or functional obstruction of the intestines.
• Flatulence (farting) results from the production of gas by bacteria within the intestines when they digest sugars and polysaccharides.
• Excessive production of gas and increased flatulence may occur because of: (1) the greater ability of some bacteria to produce gas; (2) maldigestion or malabsorption of sugars and polysaccharides; and (3) bacterial overgrowth of the small intestine.
• Belching, bloating/distention, and flatulence are evaluated with a medical history, simple abdominal X-rays, small intestinal X-rays, gastric emptying studies,ultrasound examination,computerized tomography (CT),magnetic resonance imaging(MRI), tests for maldigestion and malabsorption, and hydrogen breath testing.
• The treatment of excessive intestinal gas depends on the underlying cause and may include dietary changes, medications that reduce the amount of gas, medications that stimulate the muscles of the intestine, or antibiotics.

What causes belching?

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The ability to belch is almost universal. Belching, also known as burping (medically referred to as eructation), is the act of expelling gas from the stomach out through the mouth. The usual cause of belching is a distended (inflated) stomach caused by swallowed air. The distention of the stomach causes abdominal discomfort, and the belching expels the air and relieves the discomfort. The common reasons for swallowing large amounts of air (aerophagia) are gulping food or drink too rapidly, anxiety, and carbonated beverages. People are often unaware that they are swallowing air. "Burping" infants during bottle or breastfeeding is important in order to expel air in the stomach that has been swallowed with the formula or milk.

Excessive air in the stomach is not the only cause of belching. For some people, belching becomes a habit and does not reflect the amount of air in their stomachs. For others, belching is a response to any type of abdominal discomfort and not just to discomfort due to increased gas. Everyone knows that when they have mild abdominal discomfort, belching often relieves the problem. This is because excessive air in the stomach often is the cause of mild abdominal discomfort. As a result, people belch whenever mild abdominal discomfort is felt regardless of its cause.

Belching is not the simple act that many people think it is. Belching requires the coordination of several activities.

• The larynx must be closed-off so that any liquid or food that might return with the air from the stomach won't get into the lungs.
• This is accomplished by voluntarily raising the larynx as is done when swallowing.
• Raising the larynx also relaxes the upper esophageal sphincter so that air can pass more easily from the esophagus into the throat.
• The lower esophageal sphincter must open so that air can pass from the stomach into the esophagus.
• While all this is occurring, the diaphragm descends just as it does when a breath is taken.
• This increases abdominal pressure and decreases pressure in the chest.
• The changes in pressure promote the flow of air from the stomach in the abdomen to the esophagus in the chest.

One unusual type of belching has been described in individuals who habitually belch. It has been demonstrated that during their belches, room air enters the esophagus and is immediately expelled without even entering the stomach, giving rise to a belch. This in and out flow of air also is likely to be the explanation for the ability of many people to belch at will, even when there is little or no air in the stomach.

If the problem causing the discomfort is not excessive air in the stomach, then belching does not provide relief from the discomfort. When belching does not ease the discomfort, the belching should be taken as a sign that something may be wrong within the abdomen and the cause of the discomfort should be sought. Belching by itself, however, does not help the physician determine what may be wrong because belching can occur in virtually any abdominal disease or condition that causes abdominal discomfort.

It is important to distinguish between bloating and distention.

• Bloating is the subjective sensation (feeling) that the abdomen is larger than normal. Thus, bloating is a symptom akin to the symptom of discomfort.
• In contrast, distention is the objective determination (physical finding) that the abdomen is larger than normal. Distention can be determined by such observations as the inability to fit into clothes or looking down at the stomach and noting that it is clearly larger than normal.

In some instances, bloating may represent a mild form of distention since the abdomen does not become physically (visibly or measurably) enlarged until its volume increases by one quart. Nevertheless, bloating should never be assumed to be the same as distention. Bloating and even mild cases of distention may be caused by relaxation of the muscles of the abdominal wall.

There are three ways in which abdominal distention can arise. The causes are an increase in air, fluid, or tissue within the abdomen. The diseases or conditions that cause an increase of any of these three factors are very different from one anther. Therefore, it is important to determine which of them is distending the abdomen.

There are two types of distention; continuous and intermittent.

• Continuous distention may be caused by the enlargement of an intra-abdominal (within the abdomen) organ, an intra-abdominal tumor, a collection of fluid around the intra-abdominal organs (ascites), or just plain obesity.
• Intermittent distention is usually due to the occasional accumulation of gas and/or fluid within the stomach, small intestine, or colon.

What causes flatulence (gas)?

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Flatulence, also known as farting, is the act of passing intestinal gas from the anus. Gas in the gastrointestinal tract has only two sources. It is either swallowed air or is produced by bacteria that normally inhabit the intestines, primarily the colon. Swallowed air is rarely the cause of excessive flatulence.

The usual source of excessive gas is intestinal bacteria. The bacteria produce the gas (primarily hydrogen and/or methane) when they digest foods, primarily sugars and nondigestible polysaccharides (for example, starch, cellulose), that have not been digested during passage through the small intestine. The bacteria also produce carbon dioxide, but the carbon dioxide is so rapidly absorbed from the intestine that very little passes in flatus.

Sugars

Sugars that are commonly poorly digested (maldigested) and malabsorbed are lactose, sorbitol, and fructose.

• Lactose is the sugar in milk. The absence of the enzyme lactase in the lining of the intestines, which is a genetic trait, causes the maldigestion. Lactase is important because it breaks apart the lactose so that it can be absorbed.
• Sorbitol is a commonly used sweetener in low calorie foods.
• Fructose, primarily as high fructose corn syrup is a commonly used sweetener in all types of candies and drinks.

Polysaccharides

Starches are another common source of intestinal gas. Starches are polysaccharides that are produced by plants and are composed of long chains of sugars, primarily fructose. Common sources of different types of starch include wheat, oats, potatoes, corn, and rice.

• Rice is the most easily digested starch, and little undigested rice starch reaches the colon and the colonic bacteria. Accordingly, the consumption of rice produces little gas.
• In contrast, some of the starches in wheat, oats, potatoes, and, to a lesser extent, corn, all may reach the colon. These starches, therefore, may result in the production of appreciable amounts of gas.
• The starch in whole grains produces more gas than the starch in refined (purified) grains. Thus, more gas is formed after eating foods made with whole wheat flour than with refined wheat flour. This difference in gas production probably occurs because of the fiber(similar to a complex starch) present in the whole grain flour. Much of this fiber is removed during the processing of whole grains into refined flour.
• Finally, certain fruits and vegetables, for example, cabbage, also contain poorly digested starches that reach the colon and are easily converted by bacteria into gas.
• Most vegetables and fruits contain cellulose, another type of polysaccharide that is not digested at all as it passes through the small intestine. However, unlike sugars and other starches, cellulose is used only very slowly by colonic bacteria. Therefore, the production of gas after the consumption of fruits and vegetables usually is not great unless the fruits and vegetables also contain sugars or polysaccharides other than cellulose.

Small amounts of air are continuously being swallowed and bacteria are constantly producing gas. Contractions of the intestinal muscles normally propel the gas through the intestines and cause the gas to be expelled. Flatulence (passing intestinal gas) prevents gas from accumulating in the intestines.

However, there are two other ways in which gas can escape the intestine.

• First, it can be absorbed across the lining of the intestine into the blood. The gas then travels in the blood and ultimately is excreted in the breath.
• Second, gas can be removed and used by certain types of bacteria within the intestine. In fact, most of the gas that is formed by bacteria in the intestines is removed by other bacteria in the intestines. (Thank goodness!)

What are the causes of intermittent abdominal bloating/distention?

Excessive production of gas

Excessive production of gas by bacteria is a common cause of intermittent abdominal bloating/distention. Bacteria can produce too much gas in three ways.

• First, the amount of gas that bacteria produce varies from individual to individual. In other words, some individuals may have bacteria that produce more gas, either because there are more of the bacteria or because their particular bacteria are better at producing gas.
• Second, there may be poor digestion and absorption of foods in the small intestine, allowing more undigested food to reach the bacteria in the colon. The more undigested food the bacteria have, the more gas they produce. Examples of diseases of that involve poor digestion and absorption include lactose intolerance, pancreatic insufficiency, and celiac disease.
• Third, bacterial overgrowth can occur in the small intestine. Under normal conditions, the bacteria that produce gas are limited to the colon. In some conditions, these bacteria spread into the small intestine. When this bacterial spread occurs, food reaches the bacteria before it can be fully digested and absorbed by the small intestine. Therefore, the bacteria in the small intestine have a lot of undigested food from which to form gas. This condition in which the gas-producing bacteria move into the small intestine is called bacterial overgrowth of the small intestine (bowel).

Excessive production of gas by bacteria usually is accompanied by flatulence. Increased flatulence may not always occur; however, since gas potentially can be eliminated in other ways such as absorption into the body, utilization by other bacteria, or possibly, by elimination at night without the awareness of the gas-passer.

Physical obstruction

An obstruction (blockage) can occur virtually anywhere from the stomach to the rectum. When the blockage is temporary or partial, it can cause intermittent abdominal bloating/distention. For example, scarring of the pylorus (pyloric stenosis) can obstruct the opening from the stomach into the intestines, thereby blocking the complete emptying of the stomach. After meals, the stomach is normally filled with food and swallowed air. Then, during the next hour or two, the stomach secretes acid and fluid, which mix with the food and assist in digestion. As a result, the stomach distends further. When the obstruction is incomplete, the food, air, and fluid eventually pass into the intestines and the bloating/distention resolves.

An obstruction in the small bowel, which is most commonly due to adhesions from a previous surgery, is another cause of intermittent abdominal distention. To make matters worse, the distention that is caused by the physical obstruction stimulates both the stomach and intestines to secrete fluid, which adds to the distention.

Severe constipation or fecal impaction (hardened stool in the rectum) can also obstruct the flow of the intestinal contents and result in distention. In this case, however, the bloating/distention usually is constant and progressive and is relieved by bowel movements or removal of the impacted stool.

Functional obstruction

A functional obstruction is not caused by an actual physical blockage, but rather by the poor functioning of the muscles of the stomach or intestines that propel the intestinal contents. When these muscles are not working normally, the intestinal contents will accumulate and distend the abdomen. Examples of functional obstruction include:

• gastroparesis (paralysis of the stomach) of diabetes;
• chronic intestinal pseudo-obstruction, an unusual condition in which the muscles of the small intestine do not work normally; and
• Hirschsprung's disease, in which a small stretch of colonic muscle does not contract normally due to missing nerves.

There is accumulating scientific evidence that some patients with abdominal bloating and distention due to gas may have a functional abnormality of the intestinal muscles that prevents gas from being normally transported through the intestine and expelled. Instead, their gas accumulates in the intestine. Among patients with irritable bowel syndrome (IBS) with abdominal bloating or distention as an important symptom, the gas accumulates in the small intestine and not the colon. The gas accumulates during the day and is greatest in the evening.

Fats in food have an effect on the intestine that mimics a functional obstruction. Dietary fat reaching the small intestine causes transport of digesting food, gas, and liquid within the intestines to slow. This can promote the accumulation of food, gas, and liquid and lead to bloating and/or distention.

Dietary fiber or fiber used for treating constipation can cause bloating without increasing the production of gas in the intestine. It is believed that this sensation of bloating (and possibly even distention) is caused by the slowed passage of gas through the intestine which is caused by fiber. Of course, some types of fiber may lead to increased production of gas because they are digested to some extent by the colonic bacteria.

Intestinal hypersensitivity

Some people appear to be very sensitive (hypersensitive) to distention of their intestines, and they may feel bloated even with normal amounts of digesting food, gas, and fluid in the intestine after a meal. The bloating may be aggravated or even progress to distention if the meal contains substantial amounts of fat, perhaps because fat slows the transit of gas and digesting food through the stomach and small intestine.

How are belching, bloating/distention, and flatulence evaluated?

Medical history

A patient's medical history is important because it directs the evaluation.

• If the bloating/distention is continuous rather than intermittent, then enlargement of abdominal organs, abdominal fluid, tumors, or obesity are probable causes.
• If the bloating/distention is associated with increased flatulence, then bacteria and excessive gas production are likely factors.
• If a diet history reveals the consumption of large amounts of milk or dairy products (lactose), sorbitol or fructose, then the maldigestion and malabsorption of these sugars may be the cause of the distention.
• When individuals complain of flatulence, it may be useful for them to count the number of times they pass gas for several days. This count can confirm the presence of excessive flatulence since the number of times gas is passed correlates well with the total amount (volume) of passed gas. As you might imagine, it is not easy to measure the amount of passed gas. It is normal to pass gas up to 20 times a day. (The average volume of gas passed daily is estimated to be about ¾ of a quart.)
• If an individual complains of excessive gas but passes gas fewer than 20 times per day, the problem is likely to be something other than too much gas. For example, the problem may be the foul odor of the gas (often due to ingestion of sulfur-containing foods), the lack of ability to control (hold back) the passing of gas, or the soiling of underwear with small amounts of stool when passing gas. All of these problems, like excessive gas, are socially embarrassing and may prompt individuals to consult a physician. These problems, however, are not due to excessive gas production, and their treatment is different.

Simple abdominal X-rays

Simple X-rays of the abdomen, particularly if they are taken during an episode of bloating or distention, can often confirm air as the cause of the distention since large amounts of air can be seen easily within the stomach and intestine. Moreover, the cause of the problem may be suggested by noting where the gas has accumulated. For example, if the air is in the stomach, emptying of the stomach is likely to be the problem.

Small intestinal X-rays

X-rays of the small intestine, in which barium is used to fill and outline the small intestine, are particularly useful for determining if there is an obstruction of the small intestine.

Gastric emptying studies

These studies measure the ability of the stomach to empty its contents. Forgastric emptying studies, a test meal that is labeled with a radioactive substance is eaten and a Geiger counter-like device is placed over the abdomen to measure how rapidly the test meal empties from the stomach. A delay in emptying of the radioactivity from the stomach can be caused by any condition that reduces emptying of the stomach (for example, pyloric stenosis, gastroparesis).

Ultrasound, CT scan, and MRI

Imaging studies, including ultrasound examination, computerized tomography (CT), and magnetic resonance imaging (MRI), are particularly useful in defining the cause of distention that is due to enlargement of the abdominal organs, abdominal fluid, and tumor.

Maldigestion and malabsorption tests

Two types of tests are used to diagnose maldigestion and malabsorption; general tests and specific tests.

The best general test is a 72 hour collection of stool that measures fat in the stool; if maldigestion and/or malabsorption exist because of pancreatic insufficiency or diseases of the lining of the small intestine for example, celiac disease), the amount of fat in the stool will increase.

Specific tests can be done for maldigestion of individual sugars that are commonly maldigested, including lactose (the sugar in milk) and sorbitol (a sweetener in low calorie foods). The specific tests require ingestion of the sugars followed by hydrogen/methane breath testing. (See below.) The sugar fructose, a commonly used sweetener, like lactose and sorbitol, also may cause abdominal bloating/distention and flatulence. However, the problem that can occur with fructose is different from that with lactose or sorbitol. Thus, as already described, lactose and sorbitol may be poorly digested by the pancreatic enzymes and small intestine. On the other hand, fructose may be digested normally but may pass so rapidly through the small intestine that there is not enough time for digestion and absorption to take place.

Hydrogen/methane breath tests

The most convenient way to test for bacterial overgrowth of the small intestine is hydrogen/methane breath testing. Normally, the gas produced by the bacteria of the colon is composed of hydrogen and/or methane. For hydrogen/methane breath testing, a non-digestible sugar, lactulose, is consumed. At regular intervals following ingestion, samples of breath are taken for analysis. When the lactulose reaches the colon, the bacteria form hydrogen and/or methane. Some of the hydrogen or methane is absorbed into the blood and eliminated in the breath where it can be measured in the samples of breath.

In normal individuals, there is one peak of hydrogen or methane when the lactulose enters the colon. In individuals who have bacterial overgrowth, there are two peaks of hydrogen or methane. The first occurs when the lactulose passes and is exposed to the bacteria in the small intestine. The second occurs when the lactulose enters the colon and is exposed to the colonic bacteria. Hydrogen breath testing for overgrowth also may be done utilizing lactose, glucose, sorbitol, or fructose as the test sugar.

How is excessive intestinal gas treated?

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The treatment of excessive intestinal gas depends on the cause.

• If there is maldigestion of specific sugars-lactose, sorbitol, or fructose--the offending sugars can be eliminated from the diet.
• In the case of lactose in milk, an alternative treatment is available. Enzymes that are similar to intestinal lactase can be added to the milk in order to break down the lactose prior to its ingestion so that it can be absorbed normally. Some people find that yogurt, in which the lactose has been broken down partially by bacteria, produces less gas than milk.
• There also are certain types of vegetables and fruits that contain types of starches that are poorly digested by people but well digested by bacteria. These include beans, lentils, cabbage, brussel sprouts, onions, carrots, apricots, and prunes. Reducing the intake of these vegetables and fruits, as well as foods made from whole grains, should reduce gas and flatulence. However, the list of gas-producing foods is rather long, and it may be difficult to eliminate them all without severely restricting the diet.
• When maldigestion is due to pancreatic insufficiency, then supplemental pancreatic enzymes can be ingested with meals to replace the missing enzymes.
• If maldigestion and/or malabsorption is caused by disease of the intestinal lining, the specific disease must be identified, most commonly through a small bowel biopsy. Then, treatment can be targeted for that condition. For example, if celiac disease is found on the biopsy, agluten-free diet can be started.
• An interesting form of treatment for excessive gas is alpha-D-galactosidase, an enzyme that is produced by a mold. This enzyme, commercially available as Beano, is consumed as either a liquid or tablet with meals. This enzyme is able to break down some of the difficult-to-digest polysaccharides in vegetables so that they may be absorbed. This prevents them from reaching the colonic bacteria and causing unnecessary production of gas. Beano has been shown to be effective in decreasing the incidence of intestinal gas.
• Two other types of treatment have been promoted for the treatment of gas; simethicone (Phazyme; Flatulex; Mylicon; Gas-X; Mylanta Gas) and activated charcoal. It is unclear if simethicone has an effect on gas in the stomach. However, it has no effect on the formation of gas in the colon. Moreover, in the stomach, simethicone would be expected only to affect swallowed air, which, as previously mentioned, is an uncommon cause of excessive intestinal gas. Nevertheless, some individuals are convinced that simethicone helps them. Activated charcoal has been shown to reduce the formation of gas in the colon, though the way in which it does so is unknown.
• If there is a physical obstruction to the emptying of the stomach or passage of food, liquid, and gas through the small intestine, then surgical correction of the obstruction is required. If the obstruction is functional, medications that promote activity of the muscles of the stomach and small intestine are given. Examples of these medicines are erythromycin or metoclopramide (Reglan).
• Bacterial overgrowth of the small bowel usually is treated with antibiotics. However, this treatment is frequently only temporarily effective or not effective at all. When antibiotics provide only a temporary benefit, it may be necessary to treat patients intermittently or even continuously with antibiotics. If antibiotics are not effective,probiotics (for example, lactobacillus) or prebiotics can be tried although their use in bacterial overgrowth has not been studied. This condition may be difficult to treat.

source:medicinenet.com

Amyotrophic Lateral Sclerosis (ALS or "Lou Gehrig's Disease")

Amyotrophic lateral sclerosis facts*

*Amyotrophic lateral sclerosis facts medical author: William C. Shiel Jr., MD, FACP, FACR

• Amyotrophic lateral sclerosis is a rapidly progressive, invariably fatal neurological disease that attacks the nerve cells responsible for controlling voluntary muscles.
• Amyotrophic lateral sclerosis, or ALS, is sometimes called Lou Gehrig's disease.
• As many as 20,000 to 30,000 people in the United States have ALS, and an estimated 5,000 people in the United States are diagnosed with the disease each year.
• Only about 5 to 10 percent of all ALS cases are inherited in the family's genes.
• Early symptoms of ALS are subtle and may include twitching, cramping, or stiffness of muscles; muscle weakness affecting an arm or a leg; slurred and nasal speech; or difficulty chewing or swallowing.
• No one test can provide a definitive diagnosis of ALS, although the presence of upper and lower motor neuron signs in a single limb is strongly suggestive.
• The cause of ALS is not known, and scientists do not yet know why ALS strikes some people and not others. Scientists have discovered that mutations in the gene that produces the SOD1 enzyme were associated with some cases of familial ALS.
• No cure has yet been found for ALS. The first drug treatment for the disease -- riluzole (Rilutek) is believed to reduce damage to motor neurons by decreasing the release of glutamate. Clinical trials with ALS patients showed that riluzole prolongs survival by several months and extends the time before a patient needs ventilation support. Other treatments for ALS are designed to relieve symptoms and improve the quality of life for patients.

What is amyotrophic lateral sclerosis?

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Amyotrophic lateral sclerosis (ALS), sometimes called Lou Gehrig's disease, is a rapidly progressive, invariably fatal neurological disease that attacks the nerve cells (neurons) responsible for controlling voluntary muscles. The disease belongs to a group of disorders known as motor neuron diseases, which are characterized by the gradual degeneration and death of motor neurons.

Motor neurons are nerve cells located in the brain, brainstem, and spinal cord that serve as controlling units and vital communication links between the nervous system and the voluntary muscles of the body. Messages from motor neurons in the brain (called upper motor neurons) are transmitted to motor neurons in the spinal cord (called lower motor neurons) and from them to particular muscles. In ALS, both the upper motor neurons and the lower motor neurons degenerate or die, ceasing to send messages to muscles. Unable to function, the muscles gradually weaken, waste away (atrophy), and twitch (fasciculations) . Eventually, the ability of the brain to start and control voluntary movement is lost.

ALS causes weakness with a wide range of disabilities (see section titled "What are the symptoms?"). Eventually, all muscles under voluntary control are affected, and patients lose their strength and the ability to move their arms, legs, and body. When muscles in the diaphragm and chest wall fail, patients lose the ability to breathe without ventilatory support. Most people with ALS die from respiratory failure, usually within 3 to 5 years from the onset of symptoms. However, about 10 percent of ALS patients survive for 10 or more years.

Although the disease usually does not impair a person's mind or intelligence, several recent studies suggest that some ALS patients may have alterations in cognitive functions such as depression and problems with decision-making and memory.

ALS does not affect a person's ability to see, smell, taste, hear, or recognize touch. Patients usually maintain control of eye muscles and bladder and bowel functions, although in the late stages of the disease most patients will need help getting to and from the bathroom.

Who gets ALS?

As many as 20,000-30,000 people in the United States have ALS, and an estimated 5,000 people in the United States are diagnosed with the disease each year. ALS is one of the most common neuromuscular diseases worldwide, and people of all races and ethnic backgrounds are affected. ALS most commonly strikes people between 40 and 60 years of age, but younger and older people also can develop the disease. Men are affected more often than women.

In 90 to 95 percent of all ALS cases, the disease occurs apparently at random with no clearly associated risk factors. Patients do not have a family history of the disease, and their family members are not considered to be at increased risk for developing ALS.

About 5 to 10 percent of all ALS cases are inherited. The familial form of ALS usually results from a pattern of inheritance that requires only one parent to carry the gene responsible for the disease. About 20 percent of all familial cases result from a specific genetic defect that leads to mutation of the enzyme known as superoxide dismutase 1 (SOD1). Research on this mutation is providing clues about the possible causes of motor neuron death in ALS. Not all familial ALS cases are due to the SOD1 mutation, therefore other unidentified genetic causes clearly exist.

What are the symptoms of ALS?

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The onset of ALS may be so subtle that the symptoms are frequently overlooked. The earliest symptoms may include twitching, cramping, or stiffness of muscles; muscle weakness affecting an arm or a leg; slurred and nasal speech; or difficulty chewing or swallowing. These general complaints then develop into more obvious weakness or atrophy that may cause a physician to suspect ALS.

The parts of the body affected by early symptoms of ALS depend on which muscles in the body are damaged first. In some cases, symptoms initially affect one of the legs, and patients experience awkwardness when walkingor running or they notice that they are tripping or stumbling more often. Some patients first see the effects of the disease on a hand or arm as they experience difficulty with simple tasks requiring manual dexterity such as buttoning a shirt, writing, or turning a key in a lock. Other patients notice speech problems.

Regardless of the part of the body first affected by the disease, muscle weakness and atrophy spread to other parts of the body as the disease progresses. Patients have increasing problems with moving, swallowing (dysphagia), and speaking or forming words (dysarthria). Symptoms of upper motor neuron involvement include tight and stiff muscles (spasticity) and exaggerated reflexes (hyperreflexia) including an overactive gag reflex. An abnormal reflex commonly called Babinski's sign (the large toe extends upward as the sole of the foot is stimulated in a certain way) also indicates upper motor neuron damage. Symptoms of lower motor neuron degeneration include muscle weakness and atrophy, muscle cramps, and fleeting twitches of muscles that can be seen under the skin (fasciculations).

To be diagnosed with ALS, patients must have signs and symptoms of both upper and lower motor neuron damage that cannot be attributed to other causes.

Although the sequence of emerging symptoms and the rate of disease progression vary from person to person, eventually patients will not be able to stand or walk, get in or out of bed on their own, or use their hands and arms. Difficulty swallowing and chewing impair the patient's ability to eat normally and increase the risk of choking. Maintaining weight will then become a problem. Because the disease usually does not affect cognitive abilities, patients are aware of their progressive loss of function and may become anxious and depressed. A small percentage of patients may experience problems with memory or decision-making, and there is growing evidence that some may even develop a form of dementia. Health care professionals need to explain the course of the disease and describe available treatment options so that patients can make informed decisions in advance. In later stages of the disease, patients have difficulty breathing as the muscles of the respiratory system weaken. Patients eventually lose the ability to breathe on their own and must depend on ventilatory support for survival. Patients also face an increased risk of pneumonia during later stages of ALS.

How is ALS diagnosed?

No one test can provide a definitive diagnosis of ALS, although the presence of upper and lower motor neuron signs in a single limb is strongly suggestive. Instead, the diagnosis of ALS is primarily based on the symptoms and signs the physician observes in the patient and a series of tests to rule out other diseases. Physicians obtain the patient's full medical history and usually conduct a neurologic examination at regular intervals to assess whether symptoms such as muscle weakness, atrophy of muscles, hyperreflexia, and spasticity are getting progressively worse.

Because symptoms of ALS can be similar to those of a wide variety of other, more treatable diseases or disorders, appropriate tests must be conducted to exclude the possibility of other conditions. One of these tests is electromyography (EMG), a special recording technique that detects electrical activity in muscles. Certain EMG findings can support the diagnosis of ALS. Another common test measures nerve conduction velocity (NCV). Specific abnormalities in the NCV results may suggest, for example, that the patient has a form of peripheral neuropathy(damage to peripheral nerves) or myopathy (muscle disease) rather than ALS. The physician may order magnetic resonance imaging (MRI), a noninvasive procedure that uses a magnetic field and radio waves to take detailed images of the brain and spinal cord. Although these MRI scans are often normal in patients with ALS, they can reveal evidence of other problems that may be causing the symptoms, such as a spinal cord tumor, aherniated disk in the neck, syringomyelia, or cervical spondylosis.

Based on the patient's symptoms and findings from the examination and from these tests, the physician may order tests on blood and urine samples to eliminate the possibility of other diseases as well as routine laboratory tests. In some cases, for example, if a physician suspects that the patient may have a myopathy rather than ALS, a muscle biopsy may be performed.

Infectious diseases such as human immunodeficiency virus (HIV), human T-cell leukemia virus (HTLV), and Lyme disease can in some cases cause ALS-like symptoms. Neurological disorders such as multiple sclerosis, post-polio syndrome, multifocal motor neuropathy, and spinal muscular atrophy also can mimic certain facets of the disease and should be considered by physicians attempting to make a diagnosis.

Because of the prognosis carried by this diagnosis and the variety of diseases or disorders that can resemble ALS in the early stages of the disease, patients may wish to obtain a second neurological opinion.

What causes ALS?

The cause of ALS is not known, and scientists do not yet know why ALS strikes some people and not others. An important step toward answering that question came in 1993 when scientists supported by the National Institute of Neurological Disorders and Stroke (NINDS) discovered that mutations in the gene that produces the SOD1 enzyme were associated with some cases of familial ALS. This enzyme is a powerful antioxidant that protects the body from damage caused by free radicals. Free radicals are highly reactive molecules produced by cells during normal metabolism. If not neutralized, free radicals can accumulate and cause random damage to the DNA and proteins within cells. Although it is not yet clear how the SOD1 gene mutation leads to motor neuron degeneration, researchers have theorized that an accumulation of free radicals may result from the faulty functioning of this gene. In support of this, animal studies have shown that motor neuron degeneration and deficits in motor function accompany the presence of the SOD1 mutation.

Studies also have focused on the role of glutamate in motor neuron degeneration. Glutamate is one of the chemical messengers or neurotransmitters in the brain. Scientists have found that, compared to healthy people, ALS patients have higher levels of glutamate in the serum and spinal fluid. Laboratory studies have demonstrated that neurons begin to die off when they are exposed over long periods to excessive amounts of glutamate. Now, scientists are trying to understand what mechanisms lead to a buildup of unneeded glutamate in the spinal fluid and how this imbalance could contribute to the development of ALS.

Autoimmune responses -- which occur when the body's immune system attacks normal cells -- have been suggested as one possible cause for motor neuron degeneration in ALS. Some scientists theorize that antibodies may directly or indirectly impair the function of motor neurons, interfering with the transmission of signals between the brain and muscles.

In searching for the cause of ALS, researchers have also studied environmental factors such as exposure to toxic or infectious agents. Other research has examined the possible role of dietary deficiency or trauma. However, as of yet, there is insufficient evidence to implicate these factors as causes of ALS.

Future research may show that many factors, including a genetic predisposition, are involved in the development of ALS.

How is ALS treated?

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No cure has yet been found for ALS. However, the Food and Drug Administration (FDA) has approved the first drug treatment for the disease -- riluzole(Rilutek). Riluzole is believed to reduce damage to motor neurons by decreasing the release of glutamate. Clinical trials with ALS patients showed that riluzole prolongs survival by several months, mainly in those with difficulty swallowing. The drug also extends the time before a patient needs ventilation support. Riluzole does not reverse the damage already done to motor neurons, and patients taking the drug must be monitored for liver damage and other possible side effects. However, this first disease-specific therapy offers hope that the progression of ALS may one day be slowed by new medications or combinations of drugs.

Other treatments for ALS are designed to relieve symptoms and improve the quality of life for patients. This supportive care is best provided by multidisciplinary teams of health care professionals such as physicians; pharmacists; physical, occupational, and speech therapists; nutritionists; social workers; and home care and hospice nurses. Working with patients and caregivers, these teams can design an individualized plan of medical and physical therapy and provide special equipment aimed at keeping patients as mobile and comfortable as possible.

Physicians can prescribe medications to help reduce fatigue, ease muscle cramps, control spasticity, and reduce excess saliva and phlegm. Drugs also are available to help patients with pain, depression, sleep disturbances, andconstipation. Pharmacists can give advice on the proper use of medications and monitor a patient's prescriptions to avoid risks of drug interactions.

Physical therapy and special equipment can enhance patients' independence and safety throughout the course of ALS. Gentle, low-impactaerobic exercise such as walking, swimming, and stationary bicycling can strengthen unaffected muscles, improve cardiovascular health, and help patients fight fatigue and depression. Range of motion and stretching exercises can help prevent painful spasticity and shortening (contracture) of muscles. Physical therapists can recommend exercises that provide these benefits without overworking muscles. Occupational therapists can suggest devices such as ramps, braces, walkers, and wheelchairs that help patients conserve energy and remain mobile.

ALS patients who have difficulty speaking may benefit from working with a speech therapist. These health professionals can teach patients adaptive strategies such as techniques to help them speak louder and more clearly. As ALS progresses, speech therapists can help patients develop ways for responding to yes-or-no questions with their eyes or by other nonverbal means and can recommend aids such as speech synthesizers and computer-based communication systems. These methods and devices help patients communicate when they can no longer speak or produce vocal sounds.

Patients and caregivers can learn from speech therapists and nutritionists how to plan and prepare numerous small meals throughout the day that provide enough calories, fiber, and fluid and how to avoid foods that are difficult to swallow. Patients may begin using suction devices to remove excess fluids or saliva and prevent choking. When patients can no longer get enough nourishment from eating, doctors may advise inserting a feeding tube into the stomach. The use of a feeding tube also reduces the risk of choking and pneumonia that can result from inhaling liquids into the lungs. The tube is not painful and does not prevent patients from eating food orally if they wish.

When the muscles that assist in breathing weaken, use of nocturnal ventilatory assistance (intermittent positive pressure ventilation [IPPV] orbilevel positive airway pressure [BIPAP]) may be used to aid breathing during sleep. Such devices artificially inflate the patient's lungs from various external sources that are applied directly to the face or body. When muscles are no longer able to maintain oxygen and carbon dioxide levels, these devices may be used full-time.

Patients may eventually consider forms of mechanical ventilation (respirators) in which a machine inflates and deflates the lungs. To be effective, this may require a tube that passes from the nose or mouth to the windpipe (trachea) and for long-term use, an operation such as atracheostomy, in which a plastic breathing tube is inserted directly in the patient's windpipe through an opening in the neck. Patients and their families should consider several factors when deciding whether and when to use one of these options. Ventilation devices differ in their effect on the patient's quality of life and in cost. Although ventilation support can ease problems with breathing and prolong survival, it does not affect the progression of ALS. Patients need to be fully informed about these considerations and the long-term effects of life without movement before they make decisions about ventilation support.

Social workers and home care and hospice nurses help patients, families, and caregivers with the medical, emotional, and financial challenges of coping with ALS, particularly during the final stages of the disease. Social workers provide support such as assistance in obtaining financial aid, arranging durable power of attorney, preparing a living will, and finding support groups for patients and caregivers. Respiratory therapists can help caregivers with tasks such as operating and maintaining respirators, and home care nurses are available not only to provide medical care but also to teach caregivers about giving tube feedings and moving patients to avoid painful skin problems and contractures. Home hospice nurses work in consultation with physicians to ensure proper medication, pain control, and other care affecting the quality of life of patients who wish to remain at home. The home hospice team can also counsel patients and caregivers about end-of-life issues.

source:medicinenet.com