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Neurology - Neuromuscular

Houston, Texas

The Cullen Building at Baylor College of Medicine.
Department of Neurology
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Amyotrophic Lateral Sclerosis (ALS)

Amyotrophic lateral sclerosis, often referred to as "Lou Gehrig's disease," is a progressive neurodegenerative disease that attacks nerve cells in the brain and the spinal cord. Motor neurons reach from the brain to the spinal cord and from the spinal cord to the muscles throughout the body. The progressive degeneration of the motor neurons in ALS eventually lead to their death. When the motor neurons die, the ability of the brain to initiate and control muscle movement is lost. With all voluntary muscle action affected, patients in the later stages of the disease become totally paralyzed. Yet, through it all, for the vast majority of people, their minds remain unaffected.

A-myo-trophic comes from the Greek language. "A" means no or negative. "Myo" refers to muscle, and "Trophic" means nourishment—"No muscle nourishment." When a muscle has no nourishment, it "atrophies" or wastes away. "Lateral" identifies the areas in a person's spinal cord where portions of the nerve cells that nourish the muscles are located. As this area degenerates it leads to scarring or hardening ("sclerosis") in the region.

As motor neurons degenerate, they can no longer send impulses to the muscle fibers that normally result in muscle movement. Early symptoms of ALS often include increasing muscle weakness, especially involving the arms and legs, speech, swallowing and breathing. When muscles no longer receive the messages from the motor neurons that they require to function, the muscles begin to atrophy (waste away). Limbs begin to look "thinner" as muscle tissue atrophies.

What are the Symptoms of ALS?

At the onset of ALS the symptoms may be so slight that they are frequently overlooked. In reference to the appearance of the symptoms and the progression of the disease, the following may occur:

  • muscle weakness in one or more of the following areas: hands, arms, legs, or the muscles of speech, swallowing or breathing
  • twitching and cramping of the muscles, especially those on the hands and feet
  • impairment of the use of the arms and legs
  • "thick speech" and difficulty in projecting the voice
  • in the more advanced stages, shortness of breath, difficulty in breathing and swallowing

It is important to note that the initial symptoms vary in different patients. Not all people with ALS experience the same symptoms or the same sequences or patterns of progression. But, progressive muscle weakness and paralysis are universally experienced.

Incidence of ALS

ALS is one of the most devastating disorders that affects the function of nerves and muscles. Based on U.S. population studies, a little over 5,600 people in the U.S. are diagnosed with ALS each year. (That's 15 new cases a day.) It is estimated that as many as 30,000 Americans have the disease at any given time. Most people who develop ALS are between the ages of 40 and 70, with an average age of 55 at the time of diagnosis. However, cases of the disease do occur in persons in their twenties and thirties. Generally though, ALS occurs in greater percentages as men and women grow older. ALS is 20% more common in men than in women. However with increasing age, the incidence of ALS is more equal between men and women. Half of all people affected with ALS live at least three or more years after diagnosis. Twenty percent live five years or more; up to ten percent will survive more than 10 years.

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