Amyotrophic Lateral Sclerosis
(ALS or "Lou Gehrig's Disease")
Amyotrophic Lateral Sclerosis (ALS) Definition
ALS: Amyotrophic lateral sclerosis. ALS has two meanings. One meaning of ALS refers to several adult diseases characterized by progressive degeneration of motor neurons. (In the UK, the term "motor neuron disease" is used for these disorders.) The second meaning of ALS refers to a specific form of motor neuron disease in which there are both upper and lower motor neuron signs.
Motor neuron diseases such as ALS are progressive chronic diseases of the nerves that come from the spinal cord and supply electrical
stimulation to the muscles. This stimulation is necessary for the movement of body parts.
Amyotrophic lateral sclerosis is quite a mouthful. The disease is therefore usually referred to simply as ALS or in North America as Lou Gehrig's disease after the great baseball player who died of it.
ALS strikes in mid-life, most often in the fifth through seventh decades of life. Men are about one-and-a-half
times more likely to have the disease as women.
ALS occurs when specific nerve cells in the brain and spinal
cord that control voluntary movement gradually degenerate. The loss
of these motor neurons causes the muscles under their control to
weaken and waste away, leading to paralysis.
ALS manifests itself in different ways, depending on which muscles weaken first. Symptoms may include
tripping and falling, loss of motor control in hands and arms,
difficulty speaking, swallowing and/or breathing, persistent fatigue,
and twitching and cramping, sometimes quite severely.
There is no cure for ALS; nor is there a proven therapy that will prevent or reverse the course of the disorder. The
Food and Drug Administration (FDA) approved riluzole, the first drug
that has been shown to prolong the survival of ALS patients. Patients
may also receive supportive treatments that address some symptoms.
ALS is progressive and fatal. The
usual causes of death of patients with motor neuron diseases are not
directly related to the disease, but result from simultaneous
additional illnesses which ultimately occur because of weakness of
the body. These illnesses are often infections. ALS usually leads to death within 5 years of the time the diagnosis of ALS is made; the range is from 2 to 7 years.
SOURCE: MedTerms.com. ALS.
What is amyotrophic lateral sclerosis?
Amyotrophic lateral sclerosis (ALS), sometimes called Lou Gehrig's disease, is a rapidly progressive, invariably fatal neurological disease that attacks the nerve cells (neurons) responsible for controlling voluntary muscles. The disease belongs to a group of disorders known as motor neuron diseases, which are characterized by the gradual degeneration and death of motor neurons.
Motor neurons are nerve cells located in the brain, brainstem, and spinal cord that serve as controlling units and vital communication links between the nervous system and the voluntary muscles of the body. Messages from motor neurons in the brain (called upper motor neurons) are transmitted to motor neurons in the spinal cord (called lower motor neurons) and from them to particular muscles. In ALS, both the upper motor neurons and the lower motor neurons degenerate or die, ceasing to send messages to muscles. Unable to function, the muscles gradually weaken, waste away (atrophy), and twitch (fasciculations). Eventually, the ability of the brain to start and control voluntary movement is lost.
ALS causes weakness with a wide range of disabilities (see section titled "What are the symptoms?"). Eventually, all muscles under voluntary control are affected, and patients lose their strength and the ability to move their arms, legs, and body. When muscles in the diaphragm and chest wall fail, patients lose the ability to breathe without ventilatory support. Most people with ALS die from respiratory failure, usually within 3 to 5 years from the onset of symptoms. However, about 10 percent of ALS patients survive for 10 or more years.
Although the disease usually does not impair a person's mind or intelligence, several recent studies suggest that some ALS patients may have alterations in cognitive functions such as depression and problems with decision-making and memory.
ALS does not affect a person's ability to see, smell, taste, hear, or recognize touch. Patients usually maintain control of eye muscles and bladder and bowel functions, although in the late stages of the disease most patients will need help getting to and from the bathroom.
Who gets ALS?
As many as 20,000-30,000 people in the United States have ALS, and an estimated 5,000 people in the United States are diagnosed with the disease each year. ALS is one of the most common neuromuscular diseases worldwide, and people of all races and ethnic backgrounds are affected. ALS most commonly strikes people between 40 and 60 years of age, but younger and older people also can develop the disease. Men are affected more often than women.
In 90 to 95 percent of all ALS cases, the disease occurs apparently at random with no clearly associated risk factors. Patients do not have a family history of the disease, and their family members are not considered to be at increased risk for developing ALS.
About 5 to 10 percent of all ALS cases are inherited. The familial form of ALS usually results from a pattern of inheritance that requires only one parent to carry the gene responsible for the disease. About 20 percent of all familial cases result from a specific
genetic defect that leads to mutation of the enzyme known as superoxide dismutase 1 (SOD1). Research on this mutation is providing clues about the possible causes of motor neuron death in ALS. Not all familial ALS cases are due to the SOD1 mutation, therefore other unidentified genetic causes clearly exist.
