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The characteristics of amyotrophic lateral sclerosis a deadly disease of the nervous system

It is characterized by the progressive degeneration and eventual death of nerve cells motor neurons in the brain, brainstem and spinal cord that facilitate communication between the nervous system and voluntary muscles of the body. Ordinarily, motor neurons in the brain upper motor neurons sent messages to motor neurons in the spinal cord lower motor neurons and then to various muscles.

ALS affects both the upper and lower motor neurons, so that the transmission of messages is interrupted, and muscles gradually weaken and waste away. As a result, the ability to initiate and control voluntary movement is lost. Ultimately, ALS leads to respiratory failure because affected individuals lose the ability to control muscles in the chest and diaphragm.

ALS is often called Lou Gehrig's disease. Muscle weakness in the legs may cause tripping and falling. Affected individuals may have difficulty swallowing dysphagiaand speech may be slowed. Gradually, additional muscles become involved.

Motor neurone disease - symptoms, diagnosis, treatment

Amyotrophic lateral sclerosis may progress quickly or slowly. People with this disorder will have exaggerated deep muscle reflexes. Marked weight loss occurs in approximately 5 percent of cases.

Multiple Sclerosis vs. ALS: Similarities and Differences

As the ability to move becomes progressively impaired, people with this disease are at increased risk for respiratory failure. People with amyotrophic lateral sclerosis are also at increased risk for acute inflammation of the lungs, caused by the inhalation of food or stomach contents aspiration pneumonia. An overall decrease in the ability to move, including the ability to swallow, may also result in inadequate nutrition. Cognitive abilities usually are not affected. As the disease progresses, typically over the course of three to five years, the individual will gradually lose the ability to stand or walk.

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In time, many patients will require mechanical assistance to breath. A small percentage of people with ALS experience a gradual stabilization of symptoms and may maintain that level plateau for a few years. Causes The exact underlying cause of amyotrophic lateral sclerosis is not known. Several factors have been proposed as possible causes of the disease, including infection with an unidentified virus, an abnormal immune response e.

However, none has been substantiated. A study reported in the January 2000 issue of the journal, Neurology, lends support to the theory that there is a viral link.

The virus, similar to Echovirus-7 which is known to cause meningitis and rare cases of encephalitis, was found in only one of 29 people who died of other causes. According to researchers, approximately 10 percent of all cases of ALS are familial.

Reports in the medical literature indicate that there are several forms of hereditary ALS that may have autosomal dominant or autosomal recessive inheritance. Symptoms associated with autosomal dominant ALS usually become apparent during adulthood, however, in rare cases, adolescent onset may occur. Individuals with autosomal recessive forms of ALS tend to develop symptoms during childhood or adolescence juvenile onset.

Human traits, including the classic genetic diseases, are the product of the interaction of two genes, one received from the father and one from the mother. The risk of transmitting the disorder from affected parent to offspring is 50 percent for each pregnancy regardless of the sex of the resulting child.

  • All content is strictly informational and should not be considered medical advice;
  • Although autosomal dominant ALS usually has adult onset, this form of the disorder typically becomes apparent by the second decade of life;
  • Although animal models cannot replicate human ALS, in order to compensate for the shortcomings of studies using human ALS autopsy samples, researchers must inevitably rely on ALS animal models that can yield very important information for clarifying the pathogenesis of ALS in humans and for the establishment of reliable therapy;
  • Information on ALS patient associations is of great importance;
  • They are made of NF subunit proteins whose expression levels must be tightly coordinated to maintain neuronal homeostasis; imbalances in this expression can lead to aggregation of NFs, a hallmark of ALS;
  • The most frequent SOD1 gene mutation is the D90A which in many European countries is inherited as a recessive trait with a characteristic slowly progressing phenotype though pedigrees with dominantly inherited D90A-SOD1 and an aggressive phenotype have also been reported.

In recessive disorders, the condition does not appear unless a person inherits the same defective gene for the same trait from each parent. If an individual receives one normal gene and one gene for the disease, the person will be a carrier for the disease, but usually will not show symptoms.

The risk of transmitting the disease to the children of a couple, both of whom are carriers for a recessive disorder, is 25 percent. Fifty percent of their children risk being carriers of the disease, but generally will not show symptoms of the disorder. Twenty-five percent of their children may receive both normal genes, one from each parent, and will be genetically normal for that particular trait. The risk is the same for each pregnancy.

In approximately 15 to 20 percent of cases of hereditary ALS, the disorder is inherited as an autosomal dominant trait due to abnormal changes mutations of a gene known as superoxide dismutase-1 SOD1. Such cases of the disorder are sometimes referred to as ALS1. The SOD1 gene encodes the enzyme called superoxide dismutase.

  • This prevents the nerves from performing as well as they once did;
  • There is no known cure for ALS, nor is there a therapy to prevent or reverse its course;
  • A-myo-trophic comes from the Greek language.

Mutations of the SOD1 gene may also occur spontaneously for unknown reasons sporadicallyresulting in isolated cases of the disease sporadic ALS. The SOD1 gene is located on the long arm q of chromosome 21 21q22.

What is ALS?

Chromosomes are found in the nucleus of all body cells. They carry the genetic characteristics of each individual. Pairs of human chromosomes are numbered from 1 through 22, with an unequal 23rd pair of X and Y chromosomes for males, and two X chromosomes for females. In some rare cases of sporadic or autosomal dominant ALS, susceptibility to the disease may result from absence of genetic material deletions from, or the presence of extra genetic material insertions within, a gene known as the NEFH or neurofilament protein, heavy polypeptide gene.

  • Additionally, the muscles that move the eyes are usually not affected;
  • The information process can not be standardized, which implies that the individual approach is to be preferred;
  • Spinal motor neurons may be ballooned due to an accumulation of phosphorylated neurofilaments, but this is a non-specific finding24.

The NEFH gene is located on the long arm of chromosome 22 22q12. In addition, a rare form of autosomal dominant ALS designated as ALS4 has been mapped to the long arm of chromosome 9 9q34.

Amyotrophic lateral sclerosis

Although autosomal dominant ALS usually has adult onset, this form of the disorder typically becomes apparent by the second decade of life. One autosomal recessive form of the disorder known as ALS2 has been linked to the long arm of chromosome 2 2q33. In October 2001, a research team reported the discovery of a gene mutation responsible for ALS2.

The findings also clarify why clinicians have confused ALS2 with another neurodegenerative disease known as juvenile primary lateral sclerosis. Different mutations of the same gene are found in the two conditions, indicating a common genetic origin. With ALS2, symptoms generally appear in the first or second decade of life and progress slowly for 10 to 15 years.

With ALS1, symptoms generally occur when the individual is in his 40s or 50s, and the disease progresses more rapidly. In addition, another autosomal recessive form of ALS designated ALS5 has been mapped to the long arm of chromosome 15 15q15. Ongoing research is being conducted to further characterize the different hereditary forms of ALS. Copper is a heavy metal that is a component of several proteins and is necessary for the proper functioning of cells.

For more information on the SOD1 gene, please see above. Free radicals are compounds produced during chemical reactions in the body. The accumulation of free radicals within bodily tissues is thought to eventually cause damage to, and impaired functioning of, cells. Certain enzymes, including the SOD enzyme, serve to neutralize or promote the elimination of harmful free radicals. Enzymes are proteins produced by cells that accelerate the rate of chemical reactions in the body.

In such cases, when copper reaches the mutated SOD1 gene, it may react abnormally, resulting in cellular damage that may ultimately cause the muscle wasting atrophy seen in individuals with ALS. This information may enable researchers to determine ways in which to inhibit the transfer of copper to the mutated SOD1 gene, possibly delaying or preventing symptoms associated with ALS.

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However, much additional research is required before it may be determined whether such findings have practical treatment implications. Affected Populations Amyotrophic lateral sclerosis is a rare disorder that affects approximately 30,000 people in the United States.

Although the median age at which symptoms develop is 55 years, symptoms may begin at any adult age. ALS affects more males than females. Approximately 60 percent of those affected are men; 40 percent of affected individuals are women. An estimated 5,000 new cases are diagnosed each year in the U. Related Disorders Symptoms of the following disorders can be similar to those of Amyotrophic lateral sclerosis. Comparisons may be useful for a differential diagnosis: Primary lateral sclerosis is a very rare neurological disorder characterized by progressive loss of upper motor neurons resulting in weakness of the muscles of the arms and legs without atrophy.

Dragging of the feet is typically followed by the inability to walk. Sensory function and intellectual capabilities are generally unaffected. Kugelberg-Welander syndrome Spinal Muscular Atrophy is a rare inherited neurological disorder, occurring in infancy, characterized by the progressive degeneration of lower motor neurons.

The symptoms of this disorder include progressive weakness leading to early repiratory complications and loss of muscle tissue, especially in the legs and an uncoordinated gait. Focal or momelic motor neuron disease affects only one area of the body, most commonly shoulder girdle muscles.

The disease progresses over several months, leaving the patient with a fixed impairment of function. Some patients later develop more extensive motor neuron disease. If focal motor neuron disease is considered as a diagnosis, care should be taken to exclude other causes of focal atrophy. Progressive bulbar palsy or pseudobulbar palsy is a variant of amyotrophic lateral sclerosis characterized by weakness and wasting atrophy of the muscles innervated by the cranial nerves i.

Progressive muscular atrophy involves lower motor neurons only. This form of the disease is characterized by weakness and wasting atrophy of the muscles of the lower body, particularly the legs. If upper motor neuron symptoms do not occur, usually within two years, then it is unlikely that amyotrophic lateral sclerosis will develop.

In this subcategory of AIDS patients, anti-viral medications known as protease inhibitors may reverse the disease, and muscle use may be restored. Diagnosis Amyotrophic lateral sclerosis is characterized by degeneration of both the upper and lower motor neurons. Some patients with ALS may initially present only with findings due to degeneration of the upper motor neurons. Lower motor neuron degeneration usually appears within three to five years in these patients.

Early symptoms of ALS may resemble those of other diseases, so diagnosis may be largely a matter of ruling out other conditions. For that purpose, certain diagnostic procedures such as magnetic resonance imaging MRI or a test to detect electrical activity in muscles electromyography or EMG may be employed.

Standard Therapies Treatment The treatment of amyotrophic lateral sclerosis generally requires a team approach and should include physicians, physical therapists, speech pathologists, pulmonary therapists, medical social workers, and nurses. The drug riluzole Rilutek is the first drug to be approved by the FDA for the treatment of amyotrophic lateral sclerosis.

The drug is manufactured by the French pharmaceutical firm, Aventis. In studies, Rilutek was shown to prolong survival on an average of three to five months, although it did not substantially delay muscle deterioration.