Amyotrophic lateral sclerosis (ALS), also known as Lou Gehrig's disease, is a nervous system disease that affects nerve cells in the brain and spinal cord, leading to loss of muscle control. The disease progressively worsens over time, and its exact cause remains unknown, though a small number of cases are inherited.
ALS typically begins with muscle twitching and weakness in an arm or leg, difficulty swallowing, or slurred speech. Over time, it affects the muscles necessary for movement, speech, eating, and breathing. There is no cure for this fatal disease.
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Symptoms of ALS vary based on which nerve cells are affected. It generally begins with muscle weakness that worsens over time. Symptoms may include:
ALS often begins in the hands, feet, arms, or legs, then spreads to other parts of the body. Muscles weaken as more nerve cells die, ultimately affecting chewing, swallowing, speaking, and breathing. Pain is generally not present in the early stages, and it remains uncommon in the later stages. ALS usually does not affect bladder control or the senses.
ALS affects motor neurons, the nerve cells controlling voluntary muscle movements. These neurons are classified into two groups:
ALS gradually causes both groups of motor neurons to deteriorate and die. This leads to loss of muscle function as neurons no longer send messages to the muscles.
Approximately 10% of ALS cases have a genetic cause, while the cause for the remaining cases is unknown. Researchers are studying the complex interactions between genes and environmental factors as potential causes.
Established risk factors for ALS include:
Other potential environmental factors include:
As ALS progresses, it can lead to serious complications:
