What is ALS?

Amyotrophic lateral sclerosis (ALS) is a rare group of neurological diseases that mainly involve the nerve cells (neurons) responsible for controlling voluntary muscle movement. Voluntary muscles produce movements like chewing, walking, breathing and talking. The disease is progressive, meaning the symptoms get worse over time. Currently, there is no cure for ALS and no effective treatment to halt, or reverse, the progression of the disease.

ALS belongs to a wider group of disorders known as motor neuron diseases, which are caused by gradual deterioration (degeneration) and death of motor neurons. Motor neurons are nerve cells that extend from the brain to the spinal cord and to muscles throughout the body. These motor neurons initiate and provide vital communication links between the brain and the voluntary muscles.

Messages from motor neurons in the brain (called upper motor neurons) are transmitted to motor neurons in the spinal cord and to motor nuclei of brain (called lower motor neurons) and from the spinal cord and motor nuclei of brain to a particular muscle or muscles.

In ALS, both the upper motor neurons and the lower motor neurons degenerate or die, and stop sending messages to the muscles. Unable to function, the muscles gradually weaken, start to twitch (called fasciculations), and waste away (atrophy). Eventually, the brain loses its ability to initiate and control voluntary movements.

Early symptoms of ALS usually include muscle weakness or stiffness. Gradually all muscles under voluntary control are affected, and individuals lose their strength and the ability to speak, eat, move, and even breathe.

Most people with ALS die from respiratory failure, usually within 3 to 5 years from when the symptoms first appear. However, about 10 percent of people with ALS survive for 10 or more years.

Causes and types

It is unclear exactly what causes ALS. There are different types, according to their signs and symptoms and whether or not there is a clear genetic association.

ALS can be sporadic or familial.

Sporadic ALS occurs randomly, and it accounts for 90 to 95 percent of cases. There is no clear risk factor or cause.

Familial ALS is inherited. Around 5 to 10 percent of cases are familial. The child of a person with ALS will have a 50 percent chance of developing the condition. Rarely, it can affect a person in their teens. Researchers are investigating which genes are involved.

Other possible causes of ALS include:

• Disorganized immune response: The immune system may attack some of the body’s cells, possibly killing nerve cells.
• Chemical imbalance: People with ALS often have higher levels of glutamate, a chemical messenger in the brain, near the motor neurons. Glutamate in high quantities is known to be toxic to nerve cells.
• Mishandling of proteins: If proteins are not processed correctly by nerve cells, abnormal proteins could potentially accumulate and cause the nerve cells to die.

Possible environmental factors

Environmental factors may also play a role.

One study has reported that military personnel deployed in the Gulf region during the 1991 war were more likely to develop ALS than military personnel deployed elsewhere.

Some possible links have been found between ALS and exposure to:

• mechanical or electrical trauma
• military service
• high levels of exercise
• high levels of agricultural chemicals
• high levels of a variety of heavy metals

However, there is no conclusive evidence that specific lifestyle changes can decrease the risk.

Signs and symptoms

The symptoms of ALS usually appear when a person is in their late 50s or early 60s, but it can happen at other ages.

Progression varies between individuals. In the early stages, signs and symptoms may be barely noticeable, but the weakness becomes more visible over time.

Common symptoms include:

• difficulty carrying out daily activities, including walking
• increased clumsiness
• weakness in the feet, hands, legs, and ankles
• cramping and twitching in the arms, shoulders, or tongue
• difficulty maintaining good posture and holding the head up
• uncontrolled outbursts of laughing or crying, known as emotional lability
• cognitive changes
• slurring of speech and difficulty with voice projection
• pain
• fatigue
• problems with saliva, and mucus
• difficulty breathing and swallowing, in the later stages

Progressive muscle weakness occurs in all cases of ALS, but this may not be the first indication of the condition.

Early symptoms often include clumsiness, abnormal limb fatigue, muscle cramps and twitches, and slurred speech. Symptoms will spread to all parts of the body as ALS progresses.

Some people may have problems with decision-making and memory, eventually leading to a form of dementia called frontotemporal dementia.

Emotional lability can cause fluctuations in mood and emotional response.

Treatment and prevention

There is no cure for ALS, so treatment aims to alleviate symptoms, prevent unnecessary complications, and slow the rate of disease progression.

ALS can cause a range of physical, mental, and social changes, so a team of specialists will often help patients manage their symptoms and care, improve their qualify of life, and prolong survival.

Riluzole (Rilutek) was approved for ALS treatment by the Food and Drug Administration (FDA) in 1995, and it appears to slow the progression of the disease. It may work by reducing the body’s levels of glutamate, an excitotoxin that has been linked to neuronal damage.

In May 2017, Radicava (Edaravone) was approved to treat ALS. It may slow the decline in physical function by one third.

A number of research projects are looking at ways to use new and existing drugs to treat different aspects of ALS. Doctors can also prescribe medications to treat the different symptoms.

Therapy

Physical therapy can help people with ALS manage pain and address mobility issues.

A physical therapist can provide help and information with:

• low-impact exercises to enhance cardiovascular fitness and overall well-being
• mobility aids, such as walkers and wheelchairs
• devices to make life easier, such as ramps

Occupational therapy can help a patient maintain their independence for longer by:

• helping patients choose adaptive equipment and assistive technologies to help them keep up their daily routines
• train them in ways to compensate for hand and arm weaknesses

Breathing therapy may be needed in time, as the respiratory muscles get weaker.

Breathing devices can help the patient breathe better at night. Some patients may need mechanical ventilation. One end of a tube is connected to a respirator, while the other end is inserted into the windpipe through a surgically-created hole in the neck, or tracheostomy.

Speech therapy is useful when ALS begins to make it harder to talk. Speech therapists can help by teaching adaptive techniques. Other methods of communication include writing and computer-based communications equipment.

Nutritional support is important, as difficulty with swallowing can make it hard to get enough nutrients. Nutritionists can advise on preparing nutritious meals that are easier to swallow. Suction devices and feeding tubes may help.