Amyotrophic Lateral Sclerosis (ALS)
Written by Ada’s Medical Knowledge Team
What is amyotrophic lateral sclerosis (ALS)?
Amyotrophic lateral sclerosis (ALS), also known motor neuron disease (MND) in the U.K. or Lou Gehrig’s Disease in the U.S., is defined as a rare, progressive neurological disorder which causes nerve damage and muscle weakness. ALS affects and destroys nerve cells, called motor neurons, which are located within the spinal cord and brain and which control muscle movement. The destruction of these nerves causes progressive muscle weakness and eventually leads to paralysis. 1
The cause of ALS is not known. Early symptoms include tingling or weakness in arms or legs, muscle cramping and sometimes changes to the voice. There is no treatment to cure ALS, though there are some medications that slow down the destruction of the nerve cells. Management of this condition aims to relieve the symptoms of ALS/MND and support the person and their family.
Around 20,000 people in the United States have ALS and 6,000 people are diagnosed with the condition each year. The course of ALS/motor neuron disease varies from person to person, but in most people the condition will progress within three to five years (see FAQs). However, there are famous examples of people living for decades with ALS, such as the physicist Stephen Hawking. 2 3 4 Although the progression of the muscle weakness is different from person to person, most people with ALS will eventually die as a result of the condition.
Symptoms of amyotrophic lateral sclerosis (ALS)
Early symptoms of amyotrophic lateral sclerosis can be different for each person. The progression of ALS may also vary from person to person. However, the common factor is a progressive weakness and wasting of muscles and eventual paralysis.
Early symptoms of ALS
- Muscle weakness and tingling in the arms, legs, or neck
- Muscle twitches in the arms, legs, shoulder or tongue
- Muscle cramps
- Stiff muscles
- Slurred speech or voice becoming more nasal
- Difficulty swallowing or chewing
- Bouts of uncontrollable emotion, such as crying or laughter, caused by pseudobulbar affect (PBA). (See FAQs)
Early symptoms of ALS/motor neuron disease might be noticed as increased clumsiness, such as tripping over, dropping items or having difficulty with fine motor skills such as writing or fastening buttons.
Progression of ALS
- Being unable to walk
- Being unable to stand
- Losing the use of hands and arms
- Having difficulty swallowing or chewing, leading to coughing or choking when eating or drinking
- Having difficulty speaking
- Having difficulty breathing
- Weight loss
Most people with ALS retain their memories, reasoning and decision-making capabilities. This retained awareness can lead to depression as the physical aspect of ALS progresses. In a small number of cases, a person with ALS may develop a form of dementia. 7
When breathing muscles become affected, the person will need support from a ventilator to continue breathing. People with ALS are also at risk of developing aspiration pneumonia, caused by inhaling food or stomach contents. 8 9
Good to know: ALS does not affect the senses, such as sight, hearing and touch. It also generally does not affect the bladder.
Causes of amyotrophic lateral sclerosis (ALS)
Amyotrophic lateral sclerosis occurs when certain types of nerve cells, called neurons, degenerate and die. Motor neurons control muscle actions which can be voluntarily controlled, such as walking, speaking and breathing. Normally, upper motor neurons in the brain transmit messages to lower motor neurons in the spinal cord, and from there to muscles. Without input from nerves, muscles do not move, and so become weak and wasted. When a person has ALS, both upper and lower motor neurons start to die. 5 10 It is the involvement of motor neurons that leads to one name for this condition being motor neuron disease.
What causes ALS is not known. Men are slightly more likely to develop ALS than women, and most people develop the condition between the ages of 55 and 75.
Some studies suggest ALS may be up to twice as common in military veterans. This is thought to be because of exposure to environmental toxins such as pesticides or lead. The U.S. Department of Veterans Affairs recognizes ALS as a service-related condition. 5 11
5 to 10 percent of amyotrophic lateral sclerosis cases are genetic. Only one parent needs to carry a gene for ALS/MND. There are thought to be at least 12 genetic mutations that can cause familial ALS. 5
Diagnosis of amyotrophic lateral sclerosis (ALS)
Diagnosis of amyotrophic lateral sclerosis is made by evaluating the symptoms and undergoing a physical examination by a neurologist. There is no single diagnostic test for ALS. However, several tests are needed to confirm the diagnosis and rule out other possible causes of symptoms, such as HIV, polio or West Nile virus. 5
There are four criteria required for a diagnosis of amyotrophic lateral sclerosis: 12
Degeneration of lower motor neurons, in the spinal cord and brainstemDegeneration of upper motor neurons, in the brainSymptoms start in one body part and spread to other parts of the bodyLack of other explanations for symptoms
- Electromyogram (EMG), which uses needles to measure electrical signals between nerves and muscles
- Nerve conduction study (NCS), which uses electrode patches to measure electrical signals along nerves
- Magnetic resonance imaging (MRI) test, which produces images of the brain and spinal cord
- Lumbar puncture (spinal tap), which uses a needle inserted between two vertebrae to withdraw spinal cord fluid for testing
- Muscle biopsy, which is rarely used and involves removing a small sample of muscle under local anaesthesia for testing
- Blood tests, to exclude other potential causes for symptoms
Treatment for amyotrophic lateral sclerosis (ALS)
There is no cure for amyotrophic lateral sclerosis. Treatment involves managing the progression of ALS and providing as good a quality of life as possible. Recent years have seen advances in the ability to manage ALS symptoms.
Riluzole is believed to work by reducing, but not reversing, damage to motor neurons. It can delay the need for a tracheostomy (see section on Breathing support). Riluzole is a tablet that should be taken twice a day. Side effects associated with riluzole include: 5 15
- Upset stomach and stomach pain
- Muscle aches
Edaravone is an antioxidant that has been shown to slow the decline of people with ALS, possibly by slowing nerve damage. It is injected intravenously and given initially for the first 14 days of a 28 day cycle, and for the first 10 days in future 28 day cycles. Side effects associated with edaravone include: 5 16
- Itchy or scaly rash
- Difficulties breathing, wheezing and chest tightness
Edaravone is not available in all countries.
Other medications can help relieve symptoms of ALS such as muscle cramps, drooling and the pseudobulbar affect.
Noninvasive ventilation (NIV): uses a mask or nose tube to deliver air into the nose and/or mouth. NIV may initially only be needed at night but, as ALS progresses, can be used all the time.
Assisted coughing: atrophy of the muscles that control coughing increase the risk of dangerous mucus plugs in the airways. An assisted coughing device can help clear the airways, or a breathing technique called breath stacking can help.
Mechanical ventilation: when breathing muscles atrophy further, a machine may be needed to inflate and deflate the lungs. Mechanical ventilation can be provided by a breathing tube through the mouth, or a tracheostomy. In a tracheostomy, a hole is made surgically in the windpipe and a breathing tube is placed through it, which is attached to a ventilator. Modern ventilators are portable and allow the person more independence. After a tracheotomy, although the vocal cords are left in place, the tracheostomy tube means that air does not pass over them, making normal speech difficult. However, there are valves available that modify the airflow in the tracheotomy tube and offer some speech retention. 18 19
Speech and physical therapy
- Cycling on a stationary bike
- Stretching exercises
Most people with ALS will need a wheelchair for mobility, and, particularly in the later stages, an electric wheelchair may be preferred and allow more independence.
Speech therapy can teach methods of communicating that are louder and clearer, and use less energy as the speaking muscles degenerate. Speech synthesizers are an option for later stages of ALS.
Preventing weight loss is an important aspect of treatment for ALS to help a person maintain strength. Nutritionists can advise on types of food that are easy to swallow and offer a healthy diet. In the later stages of ALS a feeding tube may be necessary to provide additional nutrition and to avoid the risk of choking. 5 17
Other names for amyotrophic lateral sclerosis
- Lou Gehrig's disease
- Charcot's disease
- Motor neuron disease
Amyotrophic lateral sclerosis (ALS) FAQs
Q: Are ALS and MS related?
A: People with multiple sclerosis (MS) have a condition where their nerve coatings (myelin) are damaged. Both conditions can cause muscle weakness and wasting, but MS is not fatal. MS tends to affect people at a younger age, and MS symptoms can come and go. In MS, vision is often affected, which is not the case in ALS.
Q: Are ALS and Muscular Dystrophy related?
A: Muscular Dystrophy is a condition where muscle tissue wastes away but nerves are not affected. It is generally inherited and is often present in early life. Amyotrophic lateral sclerosis affects a person’s nervous system.
Q: Why is ALS/MND also called Lou Gehrig’s disease?
A: Lou Gehrig was a famous baseball player for the New York Yankees. He was diagnosed with amyotrophic lateral sclerosis in 1939 and died in 1941, though there is some modern debate about whether his death was actually caused by neurological injuries caused by concussions received while playing baseball. Lou Gehrig was the first well-known person to develop ALS in the United States, so the condition became popularly associated with him.
Q: Is ALS always fatal?
A: Yes. Most people with amyotrophic lateral sclerosis die from respiratory failure within three to five years of symptoms first appearing. However, life expectancy for people with ALS can be longer: 10 percent of people with ALS will live another 10 years and 5 percent will live another 20 years or more. 2
Q: Is ALS genetic?
A: In most cases of amyotrophic lateral sclerosis the cause is unknown. However, in around 5 to 10 percent of cases, there is thought to be a genetic factor. See the section on Familial ALS.
Q: What is the pseudobulbar affect?
A: The pseudobulbar affect (PBA) is a condition that causes uncontrolled laughing and crying that is not appropriate for the situation. A person may laugh uproariously at a joke that others find only mildly amusing, or may experience a bout of crying in response to a sad television show. Crying is more common than laughter, and PBA can be mistaken for depression. However, the mood of a person with pseudobulbar affect is normal between episodes.