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Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis

Definition

Amyotrophic lateral sclerosis (ALS) is a disease that breaks down tissues in the nervous system (a neurodegenerative disease) of unknown cause that affects the nerves responsible for movement. It is also known as motor neuron disease and Lou Gehrig's disease, after the baseball player whose career it ended.

Description

ALS is a disease of the motor neurons, those nerve cells reaching from the brain to the spinal cord (upper motor neurons) and the spinal cord to the peripheral nerves (lower motor neurons) that control muscle movement. In ALS, for unknown reasons, these neurons die, leading to a progressive loss of the ability to move virtually any of the muscles in the body. ALS affects "voluntary" muscles, those controlled by conscious thought, such as the arm, leg, and trunk muscles. ALS, in and of itself, does not affect sensation, thought processes, the heart muscle, or the "smooth" muscle of the digestive system, bladder, and other internal organs. Most people with ALS retain function of their eye muscles as well. However, various forms of ALS may be associated with a loss of intellectual function (dementia ) or sensory symptoms.

"Amyotrophic" refers to the loss of muscle bulk, a cardinal sign of ALS. "Lateral" indicates one of the regions of the spinal cord affected, and "sclerosis" describes the hardened tissue that develops in place of healthy nerves. ALS affects approximately 30,000 people in the United States, with about 5,000 new cases each year. It usually begins between the ages of 40 and 70, although younger onset is possible. Men are slightly more likely to develop ALS than women.

ALS progresses rapidly in most cases. It is fatal within three years for 50% of all people affected, and within five years for 80%. Ten percent of people with ALS live beyond eight years.

Causes and symptoms

Causes

The symptoms of ALS are caused by the death of motor neurons in the spinal cord and brain. Normally, these neurons convey electrical messages from the brain to the muscles to stimulate movement in the arms, legs, trunk, neck, and head. As motor neurons die, the muscles they enervate cannot be moved as effectively, and weakness results. In addition, lack of stimulation leads to muscle wasting, or loss of bulk. Involvement of the upper motor neurons causes spasms and increased tone in the limbs, and abnormal reflexes. Involvement of the lower motor neurons causes muscle wasting and twitching (fasciculations).

Although many causes of motor neuron degeneration have been suggested for ALS, none has yet been proven responsible. Results of recent research have implicated toxic molecular fragments known as free radicals. Some evidence suggests that a cascade of events leads to excess free radical production inside motor neurons, leading to their death. Why free radicals should be produced in excess amounts is unclear, as is whether this excess is the cause or the effect of other degenerative processes. Additional agents within this toxic cascade may include excessive levels of a neurotransmitter known as glutamate, which may over-stimulate motor neurons, thereby increasing free-radical production, and a faulty detoxification enzyme known as SOD-1, for superoxide dismutase type 1. The actual pathway of destruction is not known, however, nor is the trigger for the rapid degeneration that marks ALS. Further research may show that other pathways are involved, perhaps ones even more important than this one. Autoimmune factors or premature aging may play some role, as could viral agents or environmental toxins.

Two major forms of ALS are known: familial and sporadic. Familial ALS accounts for about 10% of all ALS cases. As the name suggests, familial ALS is believed to be caused by the inheritance of one or more faulty genes. About 15% of families with this type of ALS have mutations in the gene for SOD-1. SOD-1 gene defects are dominant, meaning only one gene copy is needed to develop the disease. Therefore, a parent with the faulty gene has a 50% chance of passing the gene along to a child.

Sporadic ALS has no known cause. While many environmental toxins have been suggested as causes, to date no research has confirmed any of the candidates investigated, including aluminum and mercury and lead from dental fillings. As research progresses, it is likely that many cases of sporadic ALS will be shown to have a genetic basis as well.

A third type, called Western Pacific ALS, occurs in Guam and other Pacific islands. This form combines symptoms of both ALS and Parkinson's disease .

Symptoms

The earliest sign of ALS is most often weakness in the arms or legs, usually more pronounced on one side than the other at first. Loss of function is usually more rapid in the legs among people with familial ALS and in the arms among those with sporadic ALS. Leg weakness may first become apparent by an increased frequency of stumbling on uneven pavement, or an unexplained difficulty climbing stairs. Arm weakness may lead to difficulty grasping and holding a cup, for instance, or loss of dexterity in the fingers.

Less often, the earliest sign of ALS is weakness in the bulbar muscles, those muscles in the mouth and throat that control chewing, swallowing, and speaking. A person with bulbar weakness may become hoarse or tired after speaking at length, or speech may become slurred.

In addition to weakness, the other cardinal signs of ALS are muscle wasting and persistent twitching (fasciculation). These are usually seen after weakness becomes obvious. Fasciculation is quite common in people without the disease, and is virtually never the first sign of ALS.

While initial weakness may be limited to one region, ALS almost always progresses rapidly to involve virtually all the voluntary muscle groups in the body. Later symptoms include loss of the ability to walk, to use the arms and hands, to speak clearly or at all, to swallow, and to hold the head up. Weakness of the respiratory muscles makes breathing and coughing difficult, and poor swallowing control increases the likelihood of inhaling food or saliva (aspiration). Aspiration increases the likelihood of lung infection, which is often the cause of death. With a ventilator and scrupulous bronchial hygiene, a person with ALS may live much longer than the average, although weakness and wasting will continue to erode any remaining functional abilities. Most people with ALS continue to retain function of the extraocular muscles that move their eyes, allowing some communication to take place with simple blinks or through use of a computer-assisted device.

Diagnosis

The diagnosis of ALS begins with a complete medical history and physical exam, plus a neurological examination to determine the distribution and extent of weakness. An electrical test of muscle function, called an electromyogram, or EMG, is an important part of the diagnostic process. Various other tests, including blood and urine tests, x rays, and CT scans, may be done to rule out other possible causes of the symptoms, such as tumors of the skull base or high cervical spinal cord, thyroid disease, spinal arthritis, lead poisoning, or severe vitamin deficiency. ALS is rarely misdiagnosed following a careful review of all these factors.

Treatment

There is no cure for ALS, and no treatment that can significantly alter its course. There are many things which can be done, however, to help maintain quality of life and to retain functional ability even in the face of progressive weakness.

As of early 1998, only one drug had been approved for treatment of ALS. Riluzole (Rilutek) appears to provide on average a three-month increase in life expectancy when taken regularly early in the disease, and shows a significant slowing of the loss of muscle strength. Riluzole acts by decreasing glutamate release from nerve terminals. Experimental trials of nerve growth factor have not demonstrated any benefit. No other drug or vitamin currently available has been shown to have any effect on the course of ALS.

A physical therapist works with an affected person and family to implement exercise and stretching programs to maintain strength and range of motion, and to promote general health. Swimming may be a good choice for people with ALS, as it provides a low-impact workout to most muscle groups. One result of chronic inactivity is contracture, or muscle shortening. Contractures limit a person's range of motion, and are often painful. Regular stretching can prevent contracture. Several drugs are available to reduce cramping, a common complaint in ALS.

An occupational therapist can help design solutions to movement and coordination problems, and provide advice on adaptive devices and home modifications.

Speech and swallowing difficulties can be minimized or delayed through training provided by a speech-language pathologist. This specialist can also provide advice on communication aids, including computer-assisted devices and simpler word boards.

Nutritional advice can be provided by a nutritionist. A person with ALS often needs softer foods to prevent jaw exhaustion or choking. Later in the disease, nutrition may be provided by a gastrostomy tube inserted into the stomach.

Mechanical ventilation may be used when breathing becomes too difficult. Modern mechanical ventilators are small and portable, allowing a person with ALS to maintain the maximum level of function and mobility. Ventilation may be administered through a mouth or nose piece, or through a tracheostomy tube. This tube is inserted through a small hole made in the windpipe. In addition to providing direct access to the airway, the tube also decreases the risk aspiration. While many people with rapidly progressing ALS choose not to use ventilators for lengthy periods, they are increasingly being used to prolong life for a short time.

The progressive nature of ALS means that most persons will eventually require full-time nursing care. This care is often provided by a spouse or other family member. While the skills involved are not difficult to learn, the physical and emotional burden of care can be over-whelming. Caregivers need to recognize and provide for their own needs as well as those of people with ALS, to prevent depression , burnout, and bitterness.

Throughout the disease, a support group can provide important psychological aid to affected persons and their caregivers as they come to terms with the losses ALS inflicts. Support groups are sponsored by both the ALS Society and the Muscular Dystrophy Association.

Alternative treatment

Given the grave prognosis and absence of traditional medical treatments, it is not surprising that a large number of alternative treatments have been tried for ALS. Two studies published in 1988 suggested that amino-acid therapies may provide some improvement for some people with ALS. While individual reports claim benefits for megavitamin therapy, herbal medicine, and removal of dental fillings, for instance, no evidence suggests that these offer any more than a brief psychological boost, often followed by a more severe letdown when it becomes apparent the disease has continued unabated. However, once the causes of ALS are better understood, alternative therapies may be more intensively studied. For example, if damage by free radicals turns out to be the root of most of the symptoms, antioxidant vitamins and supplements may be used more routinely to slow the progression of ALS. Or, if environmental toxins are implicated, alternative therapies with the goal of detoxifying the body may be of some use.

Prognosis

ALS usually progresses rapidly, and leads to death from respiratory infection within three to five years in most cases. The slowest disease progression is seen in those who are young and have their first symptoms in the limbs. About 10% of people with ALS live longer than eight years.

Prevention

There is no known way to prevent ALS or to alter its course.

Resources

BOOKS

Adams, Raymond D., Maurice Victor, and Allan H. Ropper. Adams'& Victor's Principles of Neurology, 6th ed. New York: McGraw Hill, 1997.

Brown, Robert H. "The motor neuron diseases." In Harrison's Principles of Internal Medicine, 14th ed., edited by Anthony S. Fauci, et al., pp. 2368-2372. New York: McGraw-Hill, 1998.

Feldman, Eva L. "Motor neuron diseases." In Cecil Textbook of Medicine, 21st ed., edited by Lee Goldman and J. Claude Bennett, pp. 2089-2092. Philadelphia: W. B. Saunders, 2000.

Kimura, Jun, and Ryuji Kaji. Physiology of ALS and Related Diseases. Amsterdam: Elsevier Science, 1997.

Mitsumoto, Hiroshi, David A. Chad, Erik Pioro, and Sid Gilman. Amyotrophic Lateral Sclerosis. New York: Oxford University Press, 1997.

PERIODICALS

Ansevin, C. F. "Treatment of ALS with pleconaril." Neurology 56, no. 5 (2001): 691-692.

Eisen, A., and M. Weber. "The motor cortex and amyotrophic lateral sclerosis." Muscle and Nerve 24, no. 4 (2001): 564-573.

Gelanis, D. F. "Respiratory Failure or Impairment in Amyotrophic Lateral Sclerosis." Current treatment options in neurology 3, no. 2 (2001): 133-138.

Ludolph, A. C. "Treatment of amyotrophic lateral sclerosiswhat is the next step?" Journal of Neurology 246, Suppl 6 (2000): 13-18.

Pasetti, C., and G. Zanini. "The physician-patient relationship in amyotrophic lateral sclerosis." Neurological Science 21, no. 5 (2000): 318-323.

Robberecht, W. "Genetics of amyotrophic lateral sclerosis." Journal of Neurology 246, Suppl 6 (2000): 2-6.

Robbins, R. A., Z. Simmons, B. A. Bremer, S. M. Walsh, and S. Fischer. "Quality of life in ALS is maintained as physical function declines." Neurology 56, no. 4 (2001): 442-444.

ORGANIZATIONS

ALS Association of America. 27001 Agoura Road, Suite 150, Calabasas Hills, CA 91301-5104. (800) 782-4747 (Information and Referral Service) or (818) 880-9007; Fax: (818) 880-9006. <http://www.alsa.org/als/>

American Academy of Family Physicians. 11400 Tomahawk Creek Parkway, Leawood, KS 66211-2672. (913) 906-6000. [email protected] <http://www.aafp.org/>.

American Academy of Neurology. 1080 Montreal Avenue, St. Paul, Minnesota 55116. (651) 695-1940; Fax: (651) 695-2791. info[email protected] <http://www.aan.com/>.

American Medical Association, 515 N. State Street, Chicago, IL 60610. (312) 464-5000. <http://www.ama-assn.org/>.

Centers for Disease Control and Prevention. 1600 Clifton Road, Atlanta, GA 30333. (404) 639-3534 or (800) 311-3435. <http://www.cdc.gov/netinfo.htm>, <http://www.cdc.gov/ncidod/eid/vol7no1/brown.htm>.

Muscular Dystrophy Association. 3300 East Sunrise Drive, Tucson, AZ 85718-3208. (520) 529-2000 or (800) 572-1717;520) 529-5300. <www.mdausa.org>.

WEBSITES

ALS Society of Canada. <http://www.als.ca/>.

ALS Survival Guide. <http://www.lougehrigsdisease.net/>.

American Academy of Family Physicians. <http://www.aafp.org/afp/990315ap/1489.html>.

National Organization for Rare Diseases. http://www.stepstn.com/cgi-win/nord.exe?proc=Redirect&type=rdb_sum&id=57.htm.

National Institute of Neurological Disorders and Stroke. <http://www.ninds.nih.gov/health_and_medical/disorders/amyotrophiclateralsclerosis_doc.htm>.

National Library of Medicine. <http://www.nlm.nih.gov/medlineplus/amyotrophiclateralsclerosis.html>.

World Federation of Neurology. <http://www.wfnals.org/>.

L. Fleming Fallon, Jr., MD, DrPH

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Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis

Definition

Amyotrophic lateral sclerosis (ALS) is a disease that breaks down tissues in the nervous system (a neurodegenerative disease) of unknown cause that affects the nerves responsible for movement. It is also known as motor neuron disease and Lou Gehrig's disease, after the baseball player whose career it ended.

Description

ALS is a disease of the motor neurons, those nerve cells reaching from the brain to the spinal cord (upper motor neurons) and the spinal cord to the peripheral nerves (lower motor neurons) that control muscle movement. In ALS, for unknown reasons, these neurons die, leading to a progressive loss of the ability to move virtually any of the muscles in the body. ALS affects "voluntary" muscles, those controlled by conscious thought, such as the arm, leg, and trunk muscles. ALS, in and of itself, does not affect sensation, thought processes, the heart muscle, or the "smooth" muscle of the digestive system, bladder, and other internal organs. Most people with ALS retain function of their eye muscles as well. However, various forms of ALS may be associated with a loss of intellectual function (dementia ) or sensory symptoms.

ALS progresses rapidly in most cases. It is fatal within three years for 50% of all people affected, and within five years for 80%. Ten percent of people with ALS live beyond eight years.

Causes and symptoms

Causes

The symptoms of ALS are caused by the death of motor neurons in the spinal cord and brain. Normally, these neurons convey electrical messages from the brain to the muscles to stimulate movement in the arms, legs, trunk, neck, and head. As motor neurons die, the muscles they enervate cannot be moved as effectively, and weakness results. In addition, lack of stimulation leads to muscle wasting, or loss of bulk. Involvement of the upper motor neurons causes spasms and increased tone in the limbs, and abnormal reflexes. Involvement of the lower motor neurons causes muscle wasting and twitching (fasciculations).

Although many causes of motor neuron degeneration have been suggested for ALS, none has yet been proven responsible. Results of recent research have implicated toxic molecular fragments known as free radicals. Some evidence suggests that a cascade of events leads to excess free radical production inside motor neurons, leading to their death. Why free radicals should be produced in excess amounts is unclear, as is whether this excess is the cause or the effect of other degenerative processes. Additional agents within this toxic cascade may include excessive levels of a neurotransmitter known as glutamate, which may over-stimulate motor neurons, thereby increasing free-radical production, and a faulty detoxification enzyme known as SOD-1, for superoxide dismutase type 1. The actual pathway of destruction is not known, however, nor is the trigger for the rapid degeneration that marks ALS. Further research may show that other pathways are involved, perhaps ones even more important than this one. Autoimmune factors or premature aging may play some role, as could viral agents or environmental toxins.

Two major forms of ALS are known: familial and sporadic. Familial ALS accounts for about 10% of all ALS cases. As the name suggests, familial ALS is believed to be caused by the inheritance of one or more faulty genes. About 15% of families with this type of ALS have mutations in the gene for SOD-1. SOD-1 gene defects are dominant, meaning only one gene copy is needed to develop the disease. Therefore, a parent with the faulty gene has a 50% chance of passing the gene along to a child.

Sporadic ALS has no known cause. While many environmental toxins have been suggested as causes, to date no research has confirmed any of the candidates investigated, including aluminum and mercury and lead from dental fillings. As research progresses, it is likely that many cases of sporadic ALS will be shown to have a genetic basis as well.

A third type, called Western Pacific ALS, occurs in Guam and other Pacific islands. This form combines symptoms of both ALS and Parkinson's disease.

Symptoms

The earliest sign of ALS is most often weakness in the arms or legs, usually more pronounced on one side than the other at first. Loss of function is usually more rapid in the legs among people with familial ALS and in the arms among those with sporadic ALS. Leg weakness may first become apparent by an increased frequency of stumbling on uneven pavement, or an unexplained difficulty climbing stairs. Arm weakness may lead to difficulty grasping and holding a cup, for instance, or loss of dexterity in the fingers.

Less often, the earliest sign of ALS is weakness in the bulbar muscles, those muscles in the mouth and throat that control chewing, swallowing, and speaking. A person with bulbar weakness may become hoarse or tired after speaking at length, or speech may become slurred.

In addition to weakness, the other cardinal signs of ALS are muscle wasting and persistent twitching (fasciculation). These are usually seen after weakness becomes obvious. Fasciculation is quite common in people without the disease, and is virtually never the first sign of ALS.

While initial weakness may be limited to one region, ALS almost always progresses rapidly to involve virtually all the voluntary muscle groups in the body. Later symptoms include loss of the ability to walk, to use the arms and hands, to speak clearly or at all, to swallow, and to hold the head up. Weakness of the respiratory muscles makes breathing and coughing difficult, and poor swallowing control increases the likelihood of inhaling food or saliva (aspiration). Aspiration increases the likelihood of lung infection, which is often the cause of death. With a ventilator and scrupulous bronchial hygiene, a person with ALS may live much longer than the average, although weakness and wasting will continue to erode any remaining functional abilities. Most people with ALS continue to retain function of the extraocular muscles that move their eyes, allowing some communication to take place with simple blinks or through use of a computer-assisted device.

KEY TERMS

Aspiration Inhalation of food or liquids into the lungs.

Bulbar muscles Muscles of the mouth and throat responsible for speech and swallowing.

Fasciculations Involuntary twitching of muscles.

Motor neuron A nerve cell that controls a muscle.

Riluzole (Rilutek) The first drug approved in the United States for the treatment of ALS.

Voluntary muscle A muscle under conscious control; contrasted with smooth muscle and heart muscle which are not under voluntary control.

Diagnosis

The diagnosis of ALS begins with a complete medical history and physical exam, plus a neurological examination to determine the distribution and extent of weakness. An electrical test of muscle function, called an electromyogram, or EMG, is an important part of the diagnostic process. Various other tests, including blood and urine tests, x rays, and CT scans, may be done to rule out other possible causes of the symptoms, such as tumors of the skull base or high cervical spinal cord, thyroid disease, spinal arthritis, lead poisoning, or severe vitamin deficiency. ALS is rarely misdiagnosed following a careful review of all these factors.

Treatment

There is no cure for ALS, and no treatment that can significantly alter its course. There are many things which can be done, however, to help maintain quality of life and to retain functional ability even in the face of progressive weakness.

As of the early 2000s, only one drug had been approved for treatment of ALS. Riluzole (Rilutek) appears to provide on average a three-month increase in life expectancy when taken regularly early in the disease, and shows a significant slowing of the loss of muscle strength. Riluzole acts by decreasing glutamate release from nerve terminals. Experimental trials of nerve growth factor have not demonstrated any benefit. No other drug or vitamin currently available has been shown to have any effect on the course of ALS.

A physical therapist works with an affected person and family to implement exercise and stretching programs to maintain strength and range of motion, and to promote general health. Swimming may be a good choice for people with ALS, as it provides a low-impact workout to most muscle groups. One result of chronic inactivity is contracture, or muscle shortening. Contractures limit a person's range of motion, and are often painful. Regular stretching can prevent contracture. Several drugs are available to reduce cramping, a common complaint in ALS.

An occupational therapist can help design solutions to movement and coordination problems, and provide advice on adaptive devices and home modifications.

Speech and swallowing difficulties can be minimized or delayed through training provided by a speech-language pathologist. This specialist can also provide advice on communication aids, including computer-assisted devices and simpler word boards.

Nutritional advice can be provided by a nutritionist. A person with ALS often needs softer foods to prevent jaw exhaustion or choking. Later in the disease, nutrition may be provided by a gastrostomy tube inserted into the stomach.

Mechanical ventilation may be used when breathing becomes too difficult. Modern mechanical ventilators are small and portable, allowing a person with ALS to maintain the maximum level of function and mobility. Ventilation may be administered through a mouth or nose piece, or through a tracheostomy tube. This tube is inserted through a small hole made in the windpipe. In addition to providing direct access to the airway, the tube also decreases the risk aspiration. While many people with rapidly progressing ALS choose not to use ventilators for lengthy periods, they are increasingly being used to prolong life for a short time.

The progressive nature of ALS means that most persons will eventually require full-time nursing care. This care is often provided by a spouse or other family member. While the skills involved are not difficult to learn, the physical and emotional burden of care can be overwhelming. Caregivers need to recognize and provide for their own needs as well as those of people with ALS, to prevent depression, burnout, and bitterness.

Throughout the disease, a support group can provide important psychological aid to affected persons and their caregivers as they come to terms with the losses ALS inflicts. Support groups are sponsored by both the ALS Society and the Muscular Dystrophy Association.

Alternative treatment

Given the grave prognosis and absence of traditional medical treatments, it is not surprising that a large number of alternative treatments have been tried for ALS. Two studies published in 1988 suggested that amino-acid therapies may provide some improvement for some people with ALS. While individual reports claim benefits for megavitamin therapy, herbal medicine, and removal of dental fillings, for instance, no evidence suggests that these offer any more than a brief psychological boost, often followed by a more severe letdown when it becomes apparent the disease has continued unabated. However, once the causes of ALS are better understood, alternative therapies may be more intensively studied. For example, if damage by free radicals turns out to be the root of most of the symptoms, antioxidant vitamins and supplements may be used more routinely to slow the progression of ALS. Or, if environmental toxins are implicated, alternative therapies with the goal of detoxifying the body may be of some use.

Prognosis

ALS usually progresses rapidly, and leads to death from respiratory infection within three to five years in most cases. The slowest disease progression is seen in those who are young and have their first symptoms in the limbs. About 10% of people with ALS live longer than eight years.

Prevention

There is no known way to prevent ALS or to alter its course.

Resources

BOOKS

Feldman, Eva L. "Motor neuron diseases." In Cecil Textbook of Medicine, edited by Lee Goldman and J. Claude Bennett, 21st ed. Philadelphia: W.B. Saunders, 2000, pp. 2089-2092.

PERIODICALS

Ansevin CF. "Treatment of ALS with pleconaril." Neurology 56, no. 5 (2001): 691-692.

Eisen, A., and M. Weber. "The motor cortex and amyotrophiclateral sclerosis." Muscle and Nerve 24, no. 4 (2001): 564-573.

Gelanis DF. "Respiratory Failure or Impairment in Amyotrophic Lateral Sclerosis." Current treatment options in neurology 3, no. 2 (2001): 133-138.

Ludolph AC. "Treatment of amyotrophic lateral sclerosis-what is the next step?" Journal of Neurology 246, Supplement 6 (2000): 13-18.

Pasetti, C., and G. Zanini. "The physician-patient relationship inamyotrophic lateral sclerosis." Neurological Science 21, no. 5 (2000): 318-323.

Robberecht W. "Genetics of amyotrophic lateral sclerosis." Journal of Neurology 246, Supplement 6 (2000): 2-6.

Robbins, R.A., Z. Simmons, B.A. Bremer, S.M. Walsh, and S. Fischer. "Quality of life in ALS is maintained as physical function declines." Neurology 56, no. 4 (2001): 442-444.

ORGANIZATIONS

American Medical Association. 515 N. State Street, Chicago, IL 60610. (312) 464-5000. http://www.ama-assn.org/.

Muscular Dystrophy Association. 3300 East Sunrise Drive, Tucson AZ 85718-3208. (520) 529-2000 or (800) 572-1717. http://www.mdausa.org.

OTHER

ALS Society of Canada. http://www.als.ca/.

ALS Survival Guide. http://www.lougehrigsdisease.net/.

American Academy of Family Physicians. http://www.aafp.org/afp/990315ap/1489.html.

National Institute of Neurological Disorders and Stroke. http://www.ninds.nih.gov/health_and_medical/disorders/amyotrophiclateralsclerosis_doc.htm.

National Library of Medicine. http://www.nlm.nih.gov/medlineplus/amyotrophiclateralsclerosis.html.

National Organization for Rare Diseases. http://www.stepstn.com/cgi-win/nord.exe?proc=Redirect&type=rdb_sum&id=57.htm.

World Federation of Neurology. http://www.wfnals.org/.

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"Amyotrophic Lateral Sclerosis." Gale Encyclopedia of Medicine, 3rd ed.. . Encyclopedia.com. 14 Nov. 2018 <https://www.encyclopedia.com>.

"Amyotrophic Lateral Sclerosis." Gale Encyclopedia of Medicine, 3rd ed.. . Encyclopedia.com. (November 14, 2018). https://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/amyotrophic-lateral-sclerosis

"Amyotrophic Lateral Sclerosis." Gale Encyclopedia of Medicine, 3rd ed.. . Retrieved November 14, 2018 from Encyclopedia.com: https://www.encyclopedia.com/medicine/encyclopedias-almanacs-transcripts-and-maps/amyotrophic-lateral-sclerosis

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Within the “Cite this article” tool, pick a style to see how all available information looks when formatted according to that style. Then, copy and paste the text into your bibliography or works cited list.

Because each style has its own formatting nuances that evolve over time and not all information is available for every reference entry or article, Encyclopedia.com cannot guarantee each citation it generates. Therefore, it’s best to use Encyclopedia.com citations as a starting point before checking the style against your school or publication’s requirements and the most-recent information available at these sites:

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amyotrophic lateral sclerosis

amyotrophic lateral sclerosis (ALS) (ā´mīətrōf´ik, sklĬrō´sĬs) or motor neuron disease, sometimes called Lou Gehrig's disease, degenerative disease that affects motor neurons in the brain and spinal cord, preventing them from sending impulses to the muscles. The muscles atrophy quickly, causing weakness, paralysis, and eventual death, usually when the muscles that control respiration fail. The intellect, eye motion, and bladder control are not affected. ALS sometimes originates in the brain, causing initial symptoms such as difficulty in swallowing or talking; in other cases it originates in the spinal cord, causing initial symptoms such as weakness in the extremities. About a tenth of ALS cases are hereditary. ALS usually develops after age 40; more men are affected than women.

There appear to be several causes of ALS, and a number of genetic mutations have been linked to about a third of all ALS cases. In 1991 a research team led by Teepu Siddique and Robert H. Brown, Jr. located a gene for familial ALS on chromosome 21. A later discovery pinpointed a mutation in the gene that codes for an enzyme, superoxide dismutase (SOD), as responsible for a percentage of familial cases. These defects do not appear to be present in the more common nonfamilial, or "sporadic," form of the disease. Since then, however, two defective proteins have been found to be associated with both inherited and sporadic ALS, one involved in regulating RNA and the other involved in clearing defective or unneeded proteins. Scientists also have studied the buildup of the chemical glutamate that occurs in ALS patients. Glutamate normally acts as a neurotransmitter in the brain, with excess amounts being absorbed by the cells. In ALS patients the reabsorption process fails, and the buildup of glutamate selectively destroys motor neurons. Other possible causes of ALS include defects in the gene that makes the neurofilament proteins that support nerve cell axons, and antibodies that interfere with calcium channels in the cells and cause a toxic buildup of calcium in the neurons.

There is no cure for ALS. Devices such as wheelchairs and speech synthesizers can help patients maintain independence. Research into treatment has concentrated on neurotrophic factors (proteins that assist nerve growth and health) and glutamate blockers. Rilutek (formerly Riluzole), the first drug approved by the Food and Drug Administration for treatment of ALS (1995), adds a few months to the life expectancy of most patients but does not relieve symptoms. Another drug, myotrophin, seemed somewhat promising in early studies (1996), but its effectiveness was not confirmed and it has not been approved. Baseball star Lou Gehrig died of ALS in 1941, bringing it national attention.

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Amyotrophic Lateral Sclerosis

AMYOTROPHIC LATERAL SCLEROSIS

DEFINITION


Amyotrophic lateral sclerosis (ALS; pronounced ay-MY-eh-TRO-fik LA-ter-el skler-OH-sis) is a neurodegenerative disease. A neurodegenerative disease is one in which nerve cells are damaged or killed. In the case of ALS, the nerve cells that are damaged are motor neurons. Motor neurons are nerve cells that control movement. ALS is also known as motor neuron disease and Lou Gehrig's disease. Lou Gehrig (190341) was a famous baseball player who died of the disease.

DESCRIPTION


Under normal circumstances, muscles move because of messages sent from the brain through the spinal cord to the muscles. These messages are carried by motor neurons. In ALS, those motor neurons die off and messages from the brain to the muscles do not flow normally. Muscles do not respond when they are supposed to or as well as they should.

The death of motor neurons affects voluntary muscles. These muscles are controlled by conscious thought. They include muscles in the legs, arms, and trunk. These muscles normally move when a person wants them to move. As ALS develops, a person loses that control over these muscles.

ALS normally does not affect other kinds of muscles, such as those in the heart or digestive system. It also has no effect on the brain. Thus, ALS patients can usually think normally, although they lose the ability to move.

ALS affects approximately thirty thousand people in the United States. About five thousand new cases are diagnosed each year. Most cases occur in people between the age of forty and seventy. Men are slightly more likely to develop ALS than women.

ALS usually progresses slowly. In about half of all patients, it causes death within three years. About 80 percent of all patients die in less than five years, and a small number (about 10 percent) survive more than eight years.

Amyotrophic Lateral Sclerosis: Words to Know

Aspiration:
Inhalation of food or saliva.
Motor neuron:
A nerve cell that controls a muscle.
Riluzole (Rilutek):
The first drug approved for the treatment of ALS.
Voluntary muscle:
A muscle under a person's conscious control.

CAUSES


No one knows what causes ALS. One or more factors cause motor neurons in the brain

and spinal cord to begin dying off. Nerve signals can no longer travel from the brain to the muscles. The patient is unable to move normally and he or she becomes weaker. Disturbed nerve messages can cause abnormal muscle movements that result in twitching and spasms. As muscle cells are not used, they begin to die off. The amount of muscle tissue decreases, causing a condition known as wasting.

Researchers have been unsuccessful in finding the cause of motor neuron death. There is some evidence that free radicals may be involved. Free radicals are very active chemicals that can damage living cells. Defective enzymes may also be a factor in the death of motor neurons. An enzyme is a naturally occurring chemical needed for many chemical reactions that occur in the body. Additional research is now being conducted to find out more about the cause or causes of ALS.

Two major forms of ALS are known: familial and sporadic. About 10 percent of all ALS cases are familial. As the name suggests, familial ALS is thought to be caused by genetic factors. Scientists have found that 15 percent of the people with familial ALS have a mutation (change) in a gene known as SOD-1. A parent with this mutated gene can pass it on to his or her children.

Sporadic ALS has no known cause. Certain chemical factors in the body, such as free radicals, may be involved. Or it, too, may result from genetic factors.

SYMPTOMS


The earliest sign of ALS is usually weakness in the arms or legs. This weakness tends to be more apparent on one side of the body than the other. Leg weakness may first become apparent by an increased frequency of stumbling on uneven pavement or difficulty in climbing stairs. Arm weakness may lead to difficulty in grasping or holding a cup, for instance, or loss of coordination in fingers.

Less commonly, the earliest sign of ALS is weakness in muscles of the mouth. This condition makes it difficult for the patient to chew, swallow and speak. He or she may become hoarse or tired after speaking or may have slurred speech.

Over time, ALS spreads to all voluntary muscle groups in the body. Later symptoms include loss of the ability to walk, to use the arms and hands, to speak clearly or at all, to swallow, and to hold up one's head. Weakness in the muscles of the respiratory (breathing) system can make breathing, coughing, and swallowing difficult. These conditions can result in the inhaling of foods or saliva (aspiration) which, in turn, can cause lung infections. Such infections are a common cause of death in ALS patients.

Respiratory problems can be reduced by inserting a mechanical ventilator in the person's throat. This breathing device can extend the patient's life, although muscle weakness and wasting are not reduced. Toward the end of the disease, ALS patients may be able to communicate only by means of eye blinks or a computer-assisted device.

DIAGNOSIS


The diagnosis of ALS begins with a complete medical history, physical examination, and neurological (nervous system) examination. An electromyogram (EMG; pronounced ih-LECK-tro-my-oh-gram) is part of the neurological exam. An EMG measures muscle function and tells how much damage has already occurred in motor neurons. A variety of blood and urine tests, X rays, and brain scans may also be conducted to rule out diseases other than ALS. ALS is rarely misdiagnosed after a review of all these factors.

TREATMENT


There is no cure for ALS. There are also no treatments that can significantly alter the course of the disease. In 1998 a new drug, riluzole (trade name Rilutek) was approved for use with ALS patients. The drug somewhat reduces the loss of muscle strength. It can extend the life of an ALS patient for an average of three months. No other drug or vitamin has been found to

have any effect on the progress of ALS.

Physical therapy can often help a patient maintain strength, retain range of motion, and promote general health. Stretching exercises and swimming are often a part of these routines. Drugs can sometimes be helpful in treating certain symptoms of ALS, such as cramping.

Various health specialists can be of help in dealing with specific problems encountered by ALS patients. An occupational therapist, for example, can help design solutions to the patient's movement and coordination problems. He or she can also help design special devices and home modifications to improve the patient's mobility.

Speech therapists can train an ALS patient to deal with problems of swallowing and speaking. A nutritionist can help patients design diets that will be easier to swallow and yet still be nutritious.

In later stages of the disease, mechanical ventilators may be necessary. Mechanical ventilators help patients to breathe more easily and can help prevent aspiration. They can be inserted through the mouth or nose or though an opening in the throat. Modern mechanical ventilators are small and portable. They allow ALS patients some degree of freedom and mobility. Under the best of circumstances, ventilators are somewhat awkward and unpleasant devices. Some ALS patients choose to use them for only short periods of time or not at all.

Most ALS patients eventually require full-time nursing care. This care is not difficult to learn and can often be provided by family members. The physical and emotional burden for caregivers, however, can be enormous. They must learn to be aware of and to find ways of dealing with their own needs as well as those of the patient.

Support groups can help caregivers in this regard. Support groups consist of other people also working with ALS patients as well as professional counselors. Support groups are sponsored by both the ALS Society and the Muscular Dystrophy Association.

Alternative Treatment

There is no scientific evidence that any form of alternative therapy has been successful in treating ALS. A number of vitamins, herbal remedies, and other natural products have been tried but, thus far, none appears to have any success. As the causes of the disease are better understood, it is possible that some alterative therapies may be found to provide relief from the disease.

PROGNOSIS


ALS usually progresses rapidly and leads to death from respiratory infection within three to five years. The disease progresses most slowly in those who are young and have their first symptoms in the arms and legs.

PREVENTION


There is no known way to prevent ALS or to alter its course.

FOR MORE INFORMATION


Books

Atkinson, David R., and Debbie Atkinson. Hope Springs Eternal: Surviving a Chronic Disease. Virginia Beach, VA: Are Press, 1999.

Horn, Robert, III. How Will They Know If I'm Dead?: Transcending Disability and Terminal Illness. Boca Raton, FL: Saint Lucie Press, 1996.

The Muscular Dystrophy Association. When a Loved One Has ALS: A Care-giver's Guide. Tucson, AZ: The Muscular Dystrophy Association, 1997.

Schwartz, Morrie. Letting Go: Morrie's Reflections on Living While Dying. New York: Dell Books, 1997.

Organizations

The ALS Association. 27001 Agoura Road, Suite 150, Calabasas Hills, CA 913015104. (800) 7824747. http://www.alsa.org.

The Muscular Dystrophy Association. 3300 East Sunrise Drive, Tucson, AZ 85718. (520) 5292000; (800) 5721717. http://www.mdausa.org.

Web sites

"Amyotrophic Lateral Sclerosis (ALS)." National Institute of Neurological Disorders and Stroke. [Online] http://www.ninds.nih.gov (accessed on June 15, 1999).

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Amyotrophic Lateral Sclerosis

Amyotrophic Lateral Sclerosis

What Happens to People with ALS?

How Is ALS Diagnosed and Treated?

Is There a Cure for ALS?

Resources

Amyotrophic lateral sclerosis (ALS) is a rare disease that affects the motor neurons of the body. These celh make up the nerves that control movement of the voluntary, or skeletal, muscles. The cause of ALS is unknown in most cases, but it is known that some cases are hereditary, or run in families. People cannot catch ALS from each other.

KEYWORDS

for searching the Internet and other reference sources

Motor neurons

Neuromuscular system

Amyotrophic lateral sclerosis (a-my-o-TROF-ik LAT-er-al skle-RO-sis) (ALS) is also called Lou Gehrigs disease after the famous baseball player who died after developing the condition. ALS is uncommon. In the United States, only one or two cases are diagnosed in every 100,000 people in a year. According to the Amyotrophic Lateral Sclerosis Association, about 30,000 Americans have ALS. ALS is rarely diagnosed in people younger than age 40. It occurs more often in men than in women. Fewer than 10 percent of cases run in families. The Pacific island Guam has been reported to have an unusually high number of people with ALS.

What Happens to People with ALS?

ALS affects the motor neurons* of the body. Typically, it produces weakness and paralysis in the muscles it affects, and it causes these muscles to waste away. About 40 percent of people with ALS first notice clumsiness in their hands when they try to perform such routine tasks as buttoning a shirt. Others may become aware of weakness in their legs, or that their speech has become slower.

* neurons
are nerve cells. Most neurons have extensions called dendrites through which they send and receive signals from other neurons.

As time goes on and ALS causes the muscles to waste away, the persons arms and legs become weaker. There may be muscle spasms, weight loss, and difficulty in breathing, eating, and swallowing. ALS does not affect the mind, however, and people with ALS are able to think as clearly as before. There is no loss of sensation, or sense of touch.

People usually die within a few years after they develop ALS. In a very few cases, symptoms may stabilize at some point, remaining the same for years without getting any worse.

How Is ALS Diagnosed and Treated?

Physicians can distinguish ALS from other diseases of the nervous system by its usually late onset in life, and by the progressive nature (worsening of symptoms) of the illness. The fact that the sense of touch is not affected also helps in diagnosis. Multiple sclerosis (MS), a more common disease affecting the nervous system, is similar to ALS, but MS attacks the nervous system in a number of different ways rather than involving only the motor nerves.

Physicians perform different kinds of medical tests to diagnose ALS. Tests may include:

  • EMG (electromyogram), which measures the electrical activity of the muscles
  • CT (computerized tomography), which uses computers and x-rays to record internal body images
  • MRI (magnetic resonance imaging), which uses magnetism to create internal body images
  • muscle or nerve biopsy in which a small sample of tissue is removed from the body and studied under a microscope
  • blood and urine studies.

How ALS Got Its Medical Name

ALS was first described and given its name by the great French neurologist Jean-Martin Charcot (18251893). Charcot noted in detail the wasting of muscles (amyotrophy) and the hardening (sclerosis) of motor nerves along the sides (laterally) of the spinal cord. In France, ALS is known as la maladie de Charcot, and in Great Britain it is called motor neurone disease.

Is There a Cure for ALS?

There is no known cure for ALS, but there are a few medications that can ease the muscle spasms and possibly even slow the rate at which symptoms get worse. People who have ALS need to be able to maintain an independent lifestyle as much as possible. Physical therapy, such as massage and regulated exercises, can reduce disability somewhat by helping the muscles to work better. Such aids as canes, walkers, and wheelchairs can help people with ALS move about and take care of themselves. Mechanical ventilation (machine-assisted breathing support) is often needed in the later stages of the disease.

Lou Gehrigs Disease

Lou Gehrig, who played first base for the New York Yankees from 1923 to 1939, was one of the greatest players in the history of baseball. His lifetime batting average was .340, and he hit .361 in six World Series. He twice led the American League in home runs, and he tied for home runs with Babe Ruth once.

Gehrig, whose nickname was the Iron Horse, also set a major league record in 1939 for playing 2,130 consecutive games. His career ended in that year, however, when he developed ALS. Because of his fame, attention was drawn to this condition. In the United States, it has commonly been referred to as Lou Gehrigs disease ever since.

Lou Gehrig was elected to the Baseball Hall of Fame in 1939. He showed his well-known winning spirit during the recognition day held in his honor at Yankee Stadium on July 4,1939, when he said: Today I consider myself the luckiest man on the face of the earth.... I may have had a tough break, but I have an awful lot to live for.

Gehrig died of ALS just two years later at the age of 37. His story was the subject of several books as well as the 1942 film Pride of the Yankees.

See also

Multiple Sclerosis

Paralysis

Resources

Books

Robinson, Ian, and Maggie Hunter. Motor Neurone Disease: Experience of Illness. London and New York: Routledge, 1998. An adult but mostly nontechnical book about ALS.

Robinson, Ray. Iron Horse: Lou Gehrig in His Time. New York: Harper Collins, 1991. A biography of Lou Gehrig, containing information about his struggle with ALS.

Organization

Amyotrophic Lateral Sclerosis Association, 27001 Agoura Road, Suite 150, Calabasas Hills, CA 91301-5104. The Amyotrophic Lateral Sclerosis Association website has information about ALS patients, families, caregivers, support groups, health care providers, and ongoing research. http://www.alsa.org

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Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis

Definition

Amyotrophic lateral sclerosis (ALS) is a progressive neurodegenerative disease that attacks the nerve cells (neurons) in the brain and spinal cord responsible for controlling voluntary muscles.

Description

ALS, also called Lou Gehrig's disease, is classified in a group of disorders called motor neuron diseases, characterized by the gradual deterioration and death of motor neurons. Neurons are cells that send and receive electrical signals over long distances within the body. Motor neurons convey impulses to control muscle contraction, and link the nervous system to the voluntary muscles of the body. Upper motor neurons located in the brain transmit signals to lower motor neurons located in the spinal cord which in turn send messages to specific muscles. In persons afflicted with ALS, one or both types of neurons degenerate or die, impairing the propagation of nervous system messages to muscles. The muscles gradually weaken, and eventually waste away (atrophy), with the result that the brain loses the ability to start and control voluntary movement.

Types of ALS

ALS occurs in five major forms:

  • Classical ALS ALS characterized by a deterioration of both upper and lower motor neurons.
  • Primary Lateral Sclerosis (PLS) ALS in which only the upper motor neurons deteriorate. This is the rarest form of the disease.
  • Progressive Bulbar Palsy (PBP) ALS that starts with difficulties in speaking, chewing and swallowing due to lower motor neuron deterioration. PBP affects about 25% of people suffering from ALS.
  • Progressive Muscular Atrophy (PMA) ALS in which only the lower motor neurons deteriorate.
  • Familial (hereditary) ALS ALS that affects more than one member of the same family. This type of ALS accounts for a very small number of people with ALS in the United States (5–10%).

Demographics

According to the ALS Association, some 5,600 people in the United States are diagnosed with ALS each year. It is estimated that as many as 30,000 Americans have the disease at any given time. Most people develop ALS between the ages of 40 and 70, with an average age of 55 at the time of diagnosis. ALS is 20% more common in men than in women. However with increasing age, the incidence of ALS is more equal between genders. ALS has a worldwide incidence of about 2 per 100,000 persons and a prevalence of 4–7 per 100,000. As is the case for both Parkinson's and Alzheimer's disease, the incidence of ALS is increasing along with the increasing longevity of the population. Information concerning the specific incidence of ALS in the elderly (aged 75 years and older) is sparse and the apparent decrease in ALS incidence in patients older than 70 years is thought to reflect mortality from competing diseases in later life.

Causes and symptoms

Causes

The cause and development of ALS is complex and appears to involve many factors. ALS is increasingly considered as a neurodegeneration of the aging nervous system, a consequence of aging promoting the formation of free radicals, or reactive oxygen species (ROS), which damage the genetic material found in the mitochondria that generate energy for the cell. This injury is greatest in cells such as neurons. The neurons that are particularly likely to be affected are those that use high levels of oxygen, such as the motor neurons of the brain and the spinal cord, both of which are known to be damaged by ALS. About 5–10% of ALS cases are hereditary with 20% of these having a mutation of the superoxide-dismutase-1 (SOD1) gene. Other candidate genes relevant to ALS are currently the object of active research. Autoimmune responses, occurring when the body's immune system attacks its own cells, have also been proposed as a possible cause for motor neuron degeneration in ALS. Researchers have also studied environmental factors such as exposure to toxic or infectious agents, and other research has examined the possible role of dietary deficiency or trauma.

Symptoms

At the onset of ALS, symptoms are often mild to the point of being frequently overlooked. They may include:

  • Muscle weakness in one or more of the following: hands, arms, legs, or muscles of speech, swallowing or breathing.
  • Cramping or twitching (fasciculation) of muscles, especially in the hands and feet.
  • Impairment of the use of the arms and legs.
  • Difficulty in projecting the voice.
  • Shortness of breath, difficulty in breathing and swallowing in later stages.

Initial ALS symptoms may be quite varied in different people and depending on the type of ALS, but muscle weakness is considered a characteristic initial sign, occurring in approximately 60% of all ALS patients. Early ALS signs usually include tripping, dropping things, abnormal fatigue of the arms and legs, slurred speech, muscle cramps and twitches, and uncontrollable fits of laughing or crying.

Diagnosis

The ALS diagnosis is difficult to establish and depends upon the recognition of characteristic symptoms supported by electrophysiological findings, since no ALS biological marker is yet available. To confirm a diagnosis of ALS, the recording of the electrical activity in muscles (electromyography, EMG) which includes conduction studies of various types, needle EMG, and tests that use transcranial magnetic stimulation of the motor cortex, are used. Nerve conduction velocity (NCV) tests are also used to exclude some of the disorders that mimic ALS. The diagnostic workup may also include a spinal tap, X-rays, magnetic resonance imaging (MRI), blood and urine studies, muscle and/or nerve biopsy, and complete neurological examination.

Treatment

Currently, there is no cure for ALS and treatment seeks to relieve symptoms and make the patient comfortable. Medications are available to relieve painful muscle cramps, control spasticity, and reduce excess saliva. Only one medication, riluzole (Rilutek), has been approved by the FDA for ALS. It is believed to reduce the level of ALS-induced injury to motor neurons and to have a modest effect on prolonging survival. Riluzole does not heal the damage already done to motor neurons, and patients must be monitored for liver damage while taking it.

As of 2008, seven new clinical trials for the treatment of ALS were being sponsored by the National Institutes of Health (NIH). One trial seeks to investigate the medication memantine when used in combination with riluzole. Other trials aim to study the effect of drugs such as Thalidomide, Tamoxifen, and the antibiotic Ceftriaxone, in patients with ALS .

QUESTIONS TO ASK YOUR DOCTOR

  • What ALS research is being done?
  • What are the medication options?
  • What are the side effects of medications?
  • How many ALS cases have you treated with riluzole?

Nutrition/Dietetic concerns

Nutritional counselling can offer ALS patients good nutrition advice while offering other dietary options when swallowing becomes difficult, following weakening of the muscles involved in chewing and moving food toward the back of the mouth. These may include meal plans that provide enough calories, fiber, and fluid, and which show patients how to avoid foods that are hard to swallow. When patients can no longer obtain sufficient nourishment from eating, a feeding tube may be inserted into the stomach. The feeding tube also prevents choking and pneumonia resulting from inhaling liquids into the lungs.

Therapy

Several types of therapies, even if not ALS-specific, are considered beneficial for ALS patients, including:

  • Heat or whirlpool therapy to relieve muscle cramping.
  • Physical therapy to maintain mobility while easing the discomfort of muscle stiffness, cramps and fluid retention.
  • Speech therapy and communication training to maintain as many verbal communication skills as possible.

Devices such as splints, corrective braces, grab bars, or reach-extenders, can also assist the performance of daily activities such as dressing, eating, and using the bathroom. Special equipment such as wheelchairs, electric beds or mattresses are also available to help provide functional independence .

Prognosis

The rate at which ALS develops can be quite variable from one person to another. The average survival time of people with ALS is three to five years, but many live five, ten or more years. In a small number of people, ALS is known to stop or halt its progression, although there is no understanding as to how this can occur.

KEY TERMS

Atrophy —A wasting or decrease in size of a body organ, tissue, or part owing to disease, injury, or lack of use.

Autoimmune response —A condition in which a person's immune system fails to recognize its own cells as being “self” and attacks its own body.

Biological marker —Measurable and quantifiable biological parameters that can be used to diagnose a disease accurately.

Electromyography (EMG) —The recording of the electrical activity in the muscle.

Fasciculation —Visible involuntary contraction or twitching of muscle fibers.

Immune system —The organs and cells that defends the body against infections and other diseases.

Magnetic resonance imaging (MRI) —An imaging method used to look inside the body without using surgery, harmful dyes or X—rays.

Motor neuron —A neuron that conveys impulses for muscle contraction or glandular secretion.

Motor neuron disease —Group of progressive neurological disorders that destroy motor neurones, the cells that control voluntary muscle activity such as speaking, walking, breathing, and swallowing.

Needle EMG —During an EMG test, a fine needle is inserted into the muscle to be tested. Recordings are made while the muscle is at rest, and then during the contraction to test muscle response.

Nerve conduction velocity (NCV) test —A test measuring the speed of signals through a nerve.

Nervous system —The system of cells, tissues and organs that regulates the body's responses to internal and external stimuli.

Neurodegeneration —Progressive loss of structure or function of neurons, including death of neurons.

Neurological disease —Disease of the nervous system.

Neuron —A nerve cell that sends and receives electrical signals over long distances within the body.

Progressive disease —Disease that increases in scope and severity, from bad to worse.

Reactive oxygen species (ROS) —Damaging molecules, including oxygen radicals and other highly reactive forms of oxygen that can harm cells.

Spasticity —Increased muscle tone that results in a tightening and shortening of a muscle.

Spinal tap —A procedure used to isolate cerebrospinal fluid for evaluation or diagnosis of disease.

Superoxide—dismutase (SOD) —An enzyme that catalyzes the decomposition of a superoxide into hydrogen peroxide and oxygen.

Transcranial magnetic stimulation (TMS) —A procedure which uses a strong magnet held outside the head to influence brain activity.

Prevention

In cases there is a family history of ALS, genetic counselling may be provided.

Caregiver concerns

ALS home caregivers are likely to be family members. According to the National Family Caregivers Association (NFCA), more than 26.6% of the adult American population provided care for a chronically ill, disabled or aged family member or friend in 2006. In becoming caregivers, most people experience new roles and relationships that are different from the ones they had with their loved one before ALS onset. Depression can strike anyone, with caregivers being especially vulnerable—it is the most common healthcare condition reported by family caregivers. They should seek healthcare professional counselling should the emotional demands of caring for a family member become too overwhelming, so as to ensure that their needs are also taken into consideration, while making time to keep doing the activities that they consider important.

Resources

BOOKS

Abramovitz, Melissa. Diseases and Disorders—Lou Gehrig's Disease. Farmington Hills, MI: Lucent Books, 2006.

Bak, Richard. Lou Gehrig—An American Classic. Dallas, TX: Taylor Trade Publishing, 1995.

Brown, Robert H., Michael Swash, and Piera Pasinelli, eds. Amyotrophic Lateral Sclerosis, 2nd ed. Malden, MA: Blackwell Science, 2006.

Dodson Wade, Mary. ALS: Lou Gehrig's Disease. Berkeley Heights, NJ: Enslow Publishers, Inc., 2001.

Eisen, Andrew, and Charles Krieger. Amyotrophic Lateral Sclerosis: A Synthesis of Research and Clinical Practice. Cambridge, UK: Cambridge University Press, 2006.

Miller, Robert G., et al. Amyotrophic Lateral Sclerosis (American Academy of Neurology). New York, NY: Demos Medical Publishing, 2004.

Mitsumoto, Hiroshi, and Theodore L. Munsat. Amyotrophic Lateral Sclerosis: A Guide for Patients and Families. New York, NY: Demos Medical Publishing, 2001.

Scott, Donald W., and William L. C. Scott. Amytrophic Lateral Sclerosis. Ottawa, ON: Trafford Publishing, 2006.

PERIODICALS

Bensimon, G., et al. “A study of riluzole in the treatment of advanced stage or elderly patients with amyotrophic lateral sclerosis.” Journal of Neurology 249, no. 5 (May 2002): 609–615.

Forbes, R. B., et al. “The epidemiology of amyotrophic lateral sclerosis in people aged 80 or over.” Age and Ageing 33, no. 2 (2004): 131–134.

OTHER

ALS Breathing Difficulties. ALS Association Fact Sheet.(February 20, 2008) http://org/files/cms/Resources/Breathing_Difficulties.pdf

Amyotrophic Lateral Sclerosis. NINDS Fact Sheet. February 07, 2008. (February 20, 2008) http://www.ninds.nih.gov/disorders/amyotrophiclateralsclerosis/detail_amyotrophiclateralsclerosis.htm

Experts Suggest Promising Drugs for ALS Clinical Trials. ALS Association, In the News. July 11, 2006. (February 20, 2008) http://www.alsa.org/patient/article.cfm?id=987

Facts About Amyotrophic Lateral Sclerosis (ALS). MDA Publications. (February 20, 2008) http://www.als-mda.org/publications/fa-als.html

What is ALS ? ALS Association Fact Sheet. (February 20, 2008) http://www.alsa.org/als/what.cfm?CFID=5786425…CFTOKEN=44408c9-d7c9125d-afd6-40f8-98a8-c46323f4f8c5

ORGANIZATIONS

The ALS Association, 27001 Agoura Road, Suite 150, Calabasas Hills, CA, 91301–5104, (818) 880–9007, (818) 880–9006, http://www.alsa.org.

The ALS Society of Canada, 265 Yorkland Boulevard, Suite 300, Toronto, Ontario, Canada, M2J 1S5, (416) 497–2267, (800) 267–4ALS, (416) 497–1256, http://www.als.ca.

National Institute of Neurological Disorders and Stroke (NINDS), P.O. Box 5801, Bethesda, MD, 20824, (301) 496–5751, (800) 352–9424, http://www.ninds.nih.gov.

Robert Packard Center for ALS Researchat Johns Hopkins, 5801 Smith Avenue, McAuley Suite 110, Baltimore, MD, 21209–3652, (410) 735–7678, http://www.alscenter.org.

Monique Laberge Ph.D.

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Amyotrophic Lateral Sclerosis

Amyotrophic lateral sclerosis

Definition

Amyotrophic lateral sclerosis (ALS) is a fatal disease that affects nerve cells in the brain and spinal cord that are responsible for movement. The motor neurons (nerve cells which send an impulse to illicit muscular contraction or movement) in an ALS patient die as a result of rapid degeneration. Voluntary muscles, controlled by motor neurons, lack proper nourishment and will weaken and atrophy (shrink) as a result. Examples of voluntary movement include stepping off of a curb or reaching for the top shelf. These activities rely on the muscles of the arms and legs. Paralysis sets in at the end-stages of ALS and leaves the patient unable to function physically, despite remaining mentally intact. There are no known causes or cures for amyotrophic lateral sclerosis, and the disease can afflict anyone. The usual cause of death is paralysis of the respiratory muscles which control breathing.

Description

Amyotrophic lateral sclerosis is a progressive disease of the central nervous system. "A" means "no," "myo" implies muscle cells, and "trophic" refers to nourishment. The nerve cells that extend from the brain to the spinal cord (upper motor neurons), and from the spinal cord to the peripheral nerves (lower motor neurons), for unexplained reasons, degenerate and die. "Lateral" refers to the areas of the spinal cord that are affected, and "sclerosis" occurs as hard tissue replaces the previously originally healthy nerve.

The parts of the body that are not affected by ALS are those areas not involved in the use of motor neurons. The mind remains very sharp and in control of sight, hearing, smell, touch and taste. Bowel and bladder functions are generally not affected. Amyotrophic lateral sclerosis rarely causes pain, yet leaves patients dependent on the care of others during advanced stages.

At any given time there are about 30,000 people in the United States with amyotrophic lateral sclerosis, and about 5,000 new cases are reported each year. ALS progresses rapidly and paralyzed patients are usually under the intensive care of nursing facilities or loved ones. This can have a devastating psychological effect on the family members and the patient. In most cases ALS is fatal within two to five years, although approximately 10% live eight years or more.

Amyotrophic lateral sclerosis is not a rare disease. ALS affects approximately seven people out of every 100,000. Most people with ALS are between 40 and 70 years of age. Approximately 5-10% of cases show a heredity pattern.

ALS, or Lou Gehrig's disease, is named after the great New York Yankee's first basemen. Lou Gehrig, known as the "Ironman" of baseball, died two years after he was diagnosed with amyotrophic lateral sclerosis.

Genetic profile

In 1991 a team of ALSA researchers linked familial ALS to chromosome 21. In 1993 it was found that there were structural defects in the SOD1 (superoxide dismutase) gene on chromosome 21. The SOD1 gene is an enzyme that protects the motor neurons from free radical damage. There is a high incidence of ALS on the island of Guam, in the Western New Guinea and on Kii peninsula of Japan leading some theorists to believe that genetic makeup may be susceptible to an environmental cause, such as the high levels of mercury and lead in these areas.

The inheritance pattern is autosomal dominant, which means that children of an affected parent have a 50% chance of inheriting the disorder. The majority of cases are due to a sporadic gene mutation, which means the mutation occurs only in the affected person. It is thought that sporadic mutations result from both biological and environmental causes. In rare cases, a mutation in NFH, the gene encoding for neurofilament (a structure that maintains cell shape) is apparent. Familial amyotrophic lateral sclerosis has been linked to other chromosomal locations but the exact genes involved have not been identified. The Institutional Review Board at Thomas Jefferson University in Philadelphia recently approved the ALS gene therapy project. The goal of the project is to inject an adeno-associated virus carrying a normal copy of an EAAT2, into an ALS patient's spinal cord where the motor neurons are dying. The hope is that the cells in that area will not die off.

Demographics

Amyotrophic lateral sclerosis affects anyone and both men and women are at equal risk. ALS may occur at any age and the odds of developing it increase with age. There have been reported cases of teenagers with ALS. A person only needs to inherit a defective gene from one parent to develop the disease.

Signs and symptoms

The disease starts slowly, affecting just one limb, such as the hands or feet, and steadily progresses to more limbs and muscles. When muscles lack the proper nourishment they require, they begin to thin and deteriorate. This condition is the hallmark of amyotrophic lateral sclerosis. Muscle wasting is due to the inability of degenerating motor neurons to elicit a signal to the muscles that allow them to function and grow. Common examples of symptoms for ALS are muscle cramps and twitching, weakness in the hands, feet, or ankles, speech slurring, and swallowing difficulties. Other early symptoms include arm and leg stiffness, foot drop, weight loss, fatigue, and difficulty making facial expressions.

One of the earliest symptoms of ALS is weakness in the bulbar muscles. These muscles in the mouth and throat assist in chewing, swallowing, and speaking. Weakness of these muscle groups usually cause problems such as slurred speech, difficulty with conversation and hoarseness of the voice.

Another symptom of ALS that usually occurs after initial symptoms appear is persistent muscle twitching (fasciculation). Fasciculation is almost never the first sign of ALS.

As the disease progresses the respiratory muscles (breathing muscles) weaken, resulting in increased difficulty with breathing, coughing and possibly inhaling food or saliva. The potential for lung infection increases and can cause death. Many patients find it more comfortable and extend their lives when assisted by ventilators at this stage of the disease. Communication becomes very difficult. One way to accomplish feedback with others is to make use of the eyes. Blinking is one mode that patients of amyotrophic lateral sclerosis will be forced to utilize, in order to continue communication.

As the disease progresses, victims gradually lose the use of their feet, hand, leg, and neck muscles, and paralysis results in affected muscle groups. They are able to speak and swallow only with great struggle. Sexual dys-function is not affected. Breathing will become increasingly difficult and the patients of ALS may decide to prolong life with the use of assisted ventilation, which may decrease the risks of death from infections such as pneumonia.

Diagnosis

ALS is difficult to diagnose. There is no one set way to test for the disease. A series of diagnostic tests will

rule out and exclude other possible causes and diseases that resemble ALS. Electro diagnostic tests such as electromyography (EMG) and nerve conduction velocity (NCV) are used to help diagnose ALS. Blood and urine tests, spinal taps, x rays, and muscle and/or nerve biopsy are performed, as well as magnetic resonance imaging (MRI), myelograms of the cervical spine and a complete neurological exam.

A second opinion is frequently recommended if ALS is suspected since it is a fatal neurological disease. After a complete medical exam and family history check has been administered, other tests such as a CT (computed tomography) scan may be done to continue ruling out other causes. Many symptoms mimic ALS such as tumors of the skull base or upper cervical spinal cord, spinal arthritis, thyroid disease, lead poisoning, and severe vitamin deficiency. Other possibilities to rule out are multiple sclerosis , spinal cord neoplasm, polyarteritis, syringomyelia, myasthenia gravis , and muscular dystrophy . Amyotrophic lateral sclerosis is hardly ever misdiagnosed after this intensive series of diagnostic tests.

Treatment and management

Currently, there is no treatment for ALS. Management aims to control the symptoms that patients

experience. Emotional, psychological and physical support, are provided to ease the difficulty associated with this disorder.

Moderate activities are recommended in the early stages of the disease. Physical therapy can help muscles stay active and delay the resulting weakness. ALS patients are encouraged to maintain a healthy diet and exercise regularly for as long as possible. Education of ALS is very important in developing an understanding of the disease, and is vital for family members as well as patients.

Although there are no set treatments for ALS there are still many special considerations that can assist in the quality of lifestyle for the patient. Implementing a physical therapy program, providing a wheelchair or walker, assistance when bathing, and suction machines to help evacuate accumulated secretions all help the ALS patient. Other considerations include providing foods that are soft and easy to swallow, skin maintenance, feeding tubes, ventilation maintenance and emotional support.

Researchers have developed a drug approved by the Food and Drug Administration (FDA) called Rilutek (riluzole). The drug was the first to have a positive effect in that it appears to extend the life of ALS patients by about three months.

Another drug, Myotrophin (somatomedin C), appears to prevent neuron loss and enhance neuron generation in animal studies.

Prognosis

Amyotrophic lateral sclerosis normally progresses rapidly and leads to death from respiratory infection within three to five years. If the person involved is young and the initial symptoms appear in the limbs, the disease tends to develop more slowly. Improved medical care prolongs the lives of ALS patients and shows promise for more effective treatments in the future.

Resources

BOOKS

Adams, Raymond D., Maurice Victor, and Allan H. Ropper. Adam's & Victor's Principles of Neurology, 6th ed. New York, McGraw Hill, 1997.

Brown, Robert H. "The motor neuron diseases." In Harrison's Principles of Internal Medicine, 14th ed., edited by Anthony S. Fauci, et al. New York: McGraw-Hill, 1998, pp. 2368-2372.

Feldman, Eva L. "Motor neuron diseases." In Cecil Textbook of Medicine, 21st ed., edited by Lee Goldman and J. Claude Bennett. Philadelphia: W.B. Saunders, 2000, pp. 2089-2092.

PERIODICALS

Foubistor, V. "Gene therapy fosters hope." American Medical News 43 (March 6, 2000).

ORGANIZATIONS

Association of America (ALSA). 27001 Agoura Rd., Suite 150, Calabasas Hills, CA 91301-5104. (818) 800-9006. Fax: (818) 880-9006. <http://www.alsa.org>.

Center for Neurologic Study. 9850 Genesee Ave., Suite 320, Lajolla, CA 92037. (858) 455-5463. Fax: (858) 455-1713. [email protected] <http://www.cnsonline.org>.

Forbes Norris ALS Research Center. Caifornia Pacific Medical Center, 2324 Sacramento St., San Francisco, CA 94115. (415) 923-3604. Fax: (415) 673-5184.

Laith Farid Gulli, MD

Brian Veillette, BS

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