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Amyotrophic lateral sclerosis, or ALS, is a disease of the nerve cells in the brain and spinal cord that are responsible for voluntary muscle movement.

ALS is also known as Lou Gehrig's disease.

Alternative Names

Lou Gehrig's disease; ALS


In about 10% of cases, ALS is caused by a genetic defect. In other cases, the cause of the nerve deterioration is unknown.

In ALS, nerve cells (neurons) waste away or die, and can no longer send messages to muscles. This eventually leads to muscle weakening, twitching, and an inability to move the arms, legs, and body. The condition slowly gets worse. When the muscles in the chest area stop working, it becomes hard or impossible to breathe on one's own. Persons with ALS eventually need a breathing machine.

ALS affects approximately 1 out of every 100,000 people.

Except for having a family member who has a hereditary form of the disease, there are no known risk factors.


Symptoms usually do not develop until after age 50. Persons with ALS have a loss of muscle strength and coordination that eventually gets worse (is progressive). This eventually makes the person unable to do routine activities, such as going up steps, getting out of a chair, or swallowing. Occasionally, breathing or swallowing muscles may be the first muscles affected.

As the disease gets worse, more muscle groups develop problems. However, ALS does not affect the senses (sight, smell, taste, hearing, touch) and it usually does not impact a person's ability to think or reason.

Symptoms include:

  • Muscle weakness, decrease in muscle strength and coordination
    • Slowly starts
    • Slowly gets worse
    • Commonly involves one limb at first, such as the hand
    • Eventually, person has difficulty lifting, climbing stairs, and walking
  • Paralysis
  • Muscle cramps
  • Voice changes, hoarseness
  • Speech problems, such as a slow or abnormal speech pattern
  • Difficulty swallowing, gags or chokes easily
  • Difficulty breathing (increasing effort required to breathe)
  • Head drop due to weak spinal and neck muscles

Additional symptoms that may be associated with this disease:

  • Muscle contractions
  • Muscle spasms
  • Muscle atrophy
  • Ankle, feet, and leg swelling
  • Weight loss
  • Drooling

Exams and Tests

A neuromuscular exam indicates weakness, often beginning in one area (such as shoulders or hips). There may be muscle tremors, spasms, twitching, or muscle atrophy (loss of tissue). Atrophy and twitching of the tongue are common.

The person's walk may be stiff or clumsy. Reflexes may be abnormal and may include loss of the gag reflex. Some patients have "emotional incontinence" in which it is hard to control crying or laughing.

Tests that may be done include:

  • EMG to see which nerves are not functioning (sensory nerves are normal)
  • Head CT or MRI of head to rule out other conditions
  • Genetic test, if there is a family history of ALS
  • Breathing test to see if respiratory muscles are affected.
  • Blood tests to rule out other conditions that may cause similar symptoms


There is no known cure for ALS. The first drug treatment for the disease is a medicine called riluzole. Riluzole may prolong life, but does not reverse or stop the disease from getting worse.

The goal of treatment is to control symptoms. Baclofen or diazepam may be used to control spasticity that interferes with activities of daily living. Trihexyphenidyl or amitriptyline may be prescribed for people with problems swallowing their own saliva.

Physical therapy, rehabilitation, use of braces or a wheelchair, or other orthopedic measures may be needed to maximize muscle function and general health.

Choking is common. Patients may need a tube placed into their stomach for feeding (gastrostomy).

A referral to an otolaryngologist may be advised. A nutritionist is helpful to prevent weight loss, especially for patients with limited ability to swallow.

The use of devices to assist in breathing includes machines that are only used at night as well as mechanical ventilation. Patients should discuss their wishes regarding artificial ventilation with their doctors.

Support Groups

Emotional support is vital in coping with the disorder, because mental functioning is not affected. Groups such as the ALS Association may be available to assist in coping with the disorder. See ALS - support group.

Outlook (Prognosis)

There is progressive loss of ability to function or care for oneself. Death often occurs within 3 to 5 years of diagnosis, although there are some rare cases of patients living decades.

Possible Complications

When to Contact a Medical Professional

Call your health care provider if symptoms suggest ALS, particularly if there is a family history of the disorder.

Call your health care provider if ALS has been diagnosed and symptoms worsen or new symptoms develop. Increased difficulty swallowing, difficulty breathing, and episodes of apnea are symptoms that require immediate attention.


Genetic counseling may be advised if there is a family history of ALS.

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