Amyotrophic Lateral Sclerosis (ALS)

Overview

Amyotrophic lateral sclerosis (ALS) is a progressive disease of the nervous system that gradually destroys motor neurons, the nerve cells in the brain and spinal cord that control voluntary muscle movement. As these nerves die, the muscles they control weaken, waste away, and eventually stop working. ALS is sometimes called Lou Gehrig's disease, after the famous baseball player who had it, and it belongs to a group of conditions known as motor neuron diseases.

ALS usually begins with subtle weakness in one part of the body, such as a hand, leg, or the muscles used for speech, and then spreads over time. Importantly, ALS typically does not affect the senses, bladder and bowel control, or thinking in most people, although a minority experience changes in thinking or behavior. There is no cure, and the disease is serious and life-shortening, but treatments and supportive care can ease symptoms, help maintain independence and comfort, and in some cases modestly slow progression. Care is best provided by a specialized, multidisciplinary team.

Symptoms

Early symptoms are often mild and easy to overlook, then become more noticeable and widespread as the disease progresses.

• Muscle weakness, often starting in a hand, arm, leg, or foot
• Muscle twitching (fasciculations) and cramps
• Tripping, stumbling, or difficulty with fine tasks such as buttoning a shirt
• Slurred speech and difficulty swallowing
• Muscle wasting and stiffness
• Progressive difficulty walking, using the hands, and, later, breathing
• In some people, changes in thinking or behavior

As ALS advances, weakness of the breathing muscles can cause shortness of breath. Sudden severe difficulty breathing or choking is an emergency and requires immediate medical care. Planning ahead with the care team helps manage these situations.

Causes

In most people the cause of ALS is unknown. It develops when motor neurons progressively break down and die, but why this happens is not fully understood.

• Sporadic ALS: The majority of cases occur with no clear cause and no family history.
• Genetic (familial) ALS: A minority of cases run in families and are linked to specific gene changes that can be passed down.
• Contributing factors: Researchers are studying how genetics, environmental exposures, and other factors may combine, but no single environmental cause has been confirmed.

ALS is not contagious. Having a family member with ALS raises risk only in the smaller, inherited forms.

Risk Factors

• Increasing age, with most cases developing in mid to later adulthood
• A family history of ALS in the inherited forms
• Certain inherited gene changes
• Male sex, slightly more often affected, though the difference narrows with age

For most people with ALS, no specific risk factor can be identified.

Diagnosis

There is no single test for ALS, so diagnosis involves recognizing the typical pattern of progressive weakness and carefully ruling out other conditions.

• Neurological examination: Assessing muscle strength, tone, reflexes, and signs of nerve damage over time.
• Electromyography (EMG) and nerve conduction studies: Tests that measure the electrical activity of muscles and nerves and are central to the diagnosis.
• MRI scans: Used to look for other conditions that could explain the symptoms.
• Blood tests and sometimes other studies: To exclude conditions that can mimic ALS.
• Genetic testing: May be offered, particularly when there is a family history.

Treatment

There is no cure for ALS, but treatment focuses on slowing progression where possible, relieving symptoms, and supporting comfort, function, and quality of life.

• Disease-modifying medicines: Certain medications may modestly slow progression in some people.
• Symptom management: Treatments for muscle cramps, stiffness, excess saliva, pain, and emotional symptoms.
• Breathing support: Devices that assist breathing, used as the breathing muscles weaken, can improve comfort and quality of life.
• Nutrition support: Help with swallowing and, when needed, feeding methods to maintain nutrition.
• Physical, occupational, and speech therapy: To maintain mobility and independence and to support communication.
• Assistive devices and palliative care: Equipment for mobility and communication, and care focused on comfort and personal goals.

A multidisciplinary ALS team coordinates this care and helps individuals and families plan ahead for changing needs.

Prevention

Because the cause of ALS is usually unknown, there is no established way to prevent it. For families affected by inherited forms, the focus is on information and planning.

• Genetic counseling for families with inherited ALS to understand risk
• Prompt evaluation of unexplained, progressive muscle weakness so the cause can be identified and managed
• Early connection with a specialized ALS care team if the diagnosis is made, to support comfort and function

When to See a Doctor

See a doctor if you develop unexplained, progressive muscle weakness, persistent twitching with weakness, frequent tripping, trouble with fine hand movements, slurred speech, or difficulty swallowing. Seek emergency care for:

• Sudden severe difficulty breathing or shortness of breath
• Choking or inability to swallow safely

Early evaluation allows the cause to be identified, other conditions to be ruled out, and supportive care to begin if ALS is diagnosed.

Related Topics

Frequently Asked Questions

References

1. National Institute of Neurological Disorders and Stroke (NINDS). Amyotrophic Lateral Sclerosis (ALS).
2. ALS Association. About ALS.
3. Mayo Clinic. Amyotrophic lateral sclerosis (ALS) — Symptoms and causes.
4. MedlinePlus, U.S. National Library of Medicine. Amyotrophic lateral sclerosis.