What is ALS?
Amyotrophic Lateral Sclerosis
The disease was identified and named in 1874 by a French physician, Jean Martin Charcot 1825–1893. The term "amyotrophic" refers to the muscle atrophy or muscle loss that occurs with ALS. "Lateral" refers to the location of affected nerves along each side of the spinal cord. "Sclerosis" refers to the hardened scar tissue that develops when nerve cells die. Also known as Motor Neurone Disease (MND)
In the United States, the disease is called Lou Gehrig's disease after the baseball legend Lou Gehrig who died from ALS in 1941.
Person or people with ALS are referred to as "PALS".
ALS is a neurological disorder characterized by progressive degeneration of motor neuron cells in the spinal cord and brain, which ultimately results in paralysis and death.
Motor neurons, among the largest of all nerve cells, reach from the brain to the spinal cord and from the spinal cord to the muscles throughout the body with connections to the brain. When they die, as with ALS, the ability of the brain to start and control muscle movement dies with them. With all voluntary muscle action affected, patients in the later stages are totally paralyzed yet, through it all, their minds remain unaffected. Half of all affected live at least three or more years after diagnosis. Twenty percent live five years or more; up to ten percent will survive more than ten years. However, there is always the possibility that any nerve group and its accompanying muscle groups will be affected.
Not all ALS patients are affected the same way. Some lose the ability to swallow, but continue to live fulfilling lives thanks to early peg tube placement. Tube feedings alleviates the stress of not being able to take in enough nourishment by mouth. Others lose the ability to move but are able to speak and to eat. Losing the ability to breathe on one's own is what causes people to die from ALS. Some people make the decision to receive mechanical ventilation, thereby prolonging their lives. Others use non-invasive ventilation, such as Bi-pap, which helps their air exchange, and gives their diaphragm a rest for part of the day, and enables them to feel more energetic while not using mechanical ventilation.
- Sporadic: characterized by a deterioration of upper and lower motor nerve cells (neurons). This type of ALS affects over two-thirds of all people with ALS.
- Familial a progressive neurological disease 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%).
- Guamanian - an extremely high incidence of ALS has been observed in Guam and the Trust Territories of the Pacific.
Primary lateral sclerosis (PLS) a progressive neurological disease in which the upper motor nerve cells (neurons) deteriorate. If the lower motor neurons are not affected within two years, the disease usually remains a pure upper motor neuron disease. This is the rarest of all forms of ALS.
Progressive bulbar palsy (PBP) a condition that starts with difficulties speaking, chewing and swallowing due to lower motor nerve cell (neuron) deterioration. This disorder affects about 25% of all people with ALS.
Progressive Muscular Atrophy (PMA) a progressive neurological disease in which the lower motor neurons deteriorate. If the upper motor neurons are not affected within two years, the disease usually remains a pure lower motor neuron disease.
Mariana Island form The Mariana Island form is a rare form of ALS described in Chamorro Indian patients from Guam.
The cause of ALS
Researchers are examining many possible causes for ALS, such as autoimmune response, in which the body attacks it own cells, and environmental causes such as exposure to toxic or infectious substances. In addition, scientists are looking for some biochemical abnormality that all people with ALS share, so that tests to detect and diagnose the disorder can be developed.
In 1991 a research team led by Teepu Siddique and Robert H. Brown, Jr. located the 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. In addition to genetic factors, scientists 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.
Amyotrophic Lateral Sclerosis Association.
National Center for Biotechnology Information.
Genes and Disease: Amyotrophic Lateral Sclerosis.
National Institute of Neurological Disorders and Stroke. Amyotrophic Lateral Sclerosis Fact Sheet.
Cochrane Review Abstracts. Available from www.Medscape.com Miller, R. G., Mitchell, J. D., & Moore, D. H. (2001). Riluzole for amyotrophic lateral sclerosis (ALS)/motor neuron disease (MND).
Synonyms of ALS Disorder Subdivisions This is an abstract of a report from the National Organization for Rare Disorders, Inc. ® (NORD). A copy of the complete report can be obtained for a small fee by visiting the NORD website. The complete report contains additional information including symptoms, causes, affected population, related disorders, standard and investigational treatments (if available), and references from medical literature. For a full-text version of this topic, see NORD