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Amyotrophic lateral sclerosis (ALS)

Amyotrophic lateral sclerosis (a-my-o-TROE-fik LAT-ur-ul skluh-ROE-sis), known as ALS, is a nervous system disease that affects nerve cells in the brain and spinal cord. ALS causes loss of muscle control. The disease gets worse over time.

ALS is often called Lou Gehrig’s disease after the baseball player who was diagnosed with it. The exact cause of the disease is still not known. A small number of cases are inherited.

ALS often begins with muscle twitching and weakness in an arm or leg, trouble swallowing or slurred speech. Eventually ALS affects control of the muscles needed to move, speak, eat and breathe. There is no cure for this fatal disease.

Symptoms of ALS vary from person to person. Symptoms depend on which nerve cells are affected. ALS generally begins with muscle weakness that spreads and gets worse over time. Symptoms might include:

ALS often starts in the hands, feet, arms or legs. Then it spreads to other parts of the body. Muscles get weaker as more nerve cells die. This eventually affects chewing, swallowing, speaking and breathing.

There’s generally no pain in the early stages of ALS. Pain also is not common in the later stages. ALS doesn’t usually affect bladder control. It also usually doesn’t affect the senses, including the ability to taste, smell, touch and hear.

ALS affects the nerve cells that control voluntary muscle movements such as walking and talking. These nerve cells are called motor neurons. There are two groups of motor neurons. The first group extends from the brain to the spinal cord to muscles throughout the body. They’re referred to as upper motor neurons. The second group extends from the spinal cord to muscles throughout the body. They’re referred to as lower motor neurons.

ALS causes both groups of motor neurons to gradually deteriorate and then die. When motor neurons are damaged, they stop sending messages to the muscles. As a result, the muscles can’t function.

For about 10% of people with ALS, a genetic cause can be identified. For the rest, the cause is not known.

Researchers continue to study possible causes of ALS. Most theories center on a complex interaction between genes and factors in the environment.

Established risk factors for ALS include:

Environmental factors, such as the following, have been associated with an increased risk of ALS.

As the disease progresses, ALS causes complications, such as:

Breathing problems

Con el tiempo, ALS leads to weakness of the muscles used to breathe. People with ALS might need a device such as a mask ventilator to help them breathe at night. The device is similar to what someone with sleep apnea might wear. This type of device supports the person’s breathing through a mask worn over the nose, the mouth or both.

Some people with advanced ALS choose to have a tracheostomy. This is a surgically created hole at the front of the neck leading to the windpipe. A ventilator may work better on a tracheostomy than on a mask.

The most common cause of death for people with ALS is breathing failure. Half of people with ALS die within 14 to 18 months of diagnosis. However, some people with ALS live 10 years or longer.

Speaking problems

Most people with ALS develop weakness of the muscles used to form speech. This usually starts with slower speech and occasional slurring of words. It then becomes harder to speak clearly. This can progress to the point that others can’t understand the person’s speech. Other forms of communication and technology are used to communicate.

Eating problems

People with ALS can develop weakness of the muscles involved with swallowing. This can lead to malnutrition and dehydration. They are also at higher risk of getting food, liquids or saliva into the lungs, which can cause pneumonia. A feeding tube can reduce these risks and ensure proper hydration and nutrition.

Dementia

Some people with ALS have problems with language and decision-making. Some are eventually diagnosed with a form of dementia called frontotemporal dementia.

Amyotrophic lateral sclerosis, known as ALS, can be hard to diagnose early because it can have symptoms similar to other diseases. Tests to rule out other conditions or help diagnose ALS might include:

Treatments can’t reverse the damage of ALS, but they can slow the progression of symptoms. They also can help prevent complications and make you more comfortable and independent.

You might need a team of health care providers and doctors trained in many areas to provide your care. The team works together to prolong your survival and improve your quality of life.

Your team works to select the right treatments for you. You have the right to choose or refuse any of the treatments suggested.

Medications

The Food and Drug Administration has approved two medicines for treating ALS:

Your health care provider also might prescribe treatments for relief of other symptoms, including:

Therapies

When ALS affects your ability to breathe, speak and move, therapies and other forms of support can help.

Potential future treatments

Based on the current understanding of ALS, researchers are conducting clinical studies on promising medicines and treatments.

Learning you have ALS can be devastating. The following tips may help you and your family cope:

Your primary care provider may be the first to recognize the symptoms of ALS. Your provider will likely refer you to a doctor trained in nervous system conditions, known as a neurologist, to establish a diagnosis.

What you can do

You might need many tests to diagnose your condition. The diagnosis process can be stressful and frustrating. These strategies might give you a greater sense of control.

What to expect from your doctor

Your primary care provider will likely review your family’s medical history and your symptoms. Your neurologist and your primary care provider might conduct a physical and neurological exam. This might include testing your:

© 1998-2024 Mayo Foundation for Medical Education and Research (MFMER). All rights reserved.

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