Amyotrophic lateral sclerosis

Alternative Names

Lou Gehrig's disease; ALS; Upper and lower motor neuron disease; Motor neuron disease

Causes, incidence, and risk factors

1 out of 10 cases of ALS are due to a genetic defect. The other times, the cause 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.

ALS affects approximately 5 out of every 100,000 people worldwide.

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

Symptoms

Symptoms usually do not develop until after age 50, but they can start in younger people. Persons with ALS have a loss of muscle strength and coordination that eventually gets worse and makes it impossible to do routine tasks such as going up steps, getting out of a chair, or swallowing.

Breathing or swallowing muscles may be the first muscles affected. As the disease gets worse, more muscle groups develop problems.

ALS does not affect the senses (sight, smell, taste, hearing, touch). It only rarely affects bladder or bowel function, eye movement, or a person's ability to think or reason.

Symptoms include:

• Difficulty breathing
• Difficulty swallowing
  • Choking easily
  • Drooling
  • Gagging
• Head drop due to weakness of the neck muscles
• Muscle cramps
• Muscle contractions called fasciculations
• Muscle weakness that slowly gets worse
  • Commonly involves one part of the body first, such as the arm or hand
  • Eventually leads to difficulty lifting, climbing stairs, and walking
• Paralysis
• Speech problems, such as a slow or abnormal speech pattern (slurring of words)
• Voice changes, hoarseness
• Weight loss

Signs and tests

The doctor or nurse will examine you and ask questions about your medical history and symptoms.

The physical exam may show: 

• Weakness, often beginning in one area
• Muscle tremors, spasms, twitching, or loss of muscle tissue 
• Twitching of the tongue (common)
• Abnormal reflexes
• Stiff or clumsy walk
• Increased reflexes at the joints
• Difficulty controlling crying or laughing (sometimes called emotional incontinence)
• Loss of gag reflex

Tests that may be done include:

• Blood tests to rule out other conditions
• Breathing test to see if lung muscles are affected
• Cervical spine CT or MRI to be sure there is no disease or injury to the neck, which can mimic ALS
• Electromyography to see which nerves or muscles do not work properly
• Genetic testing, if there is a family history of ALS
• Head CT or MRI to rule out other conditions
• Swallowing studies
• Spinal tap (lumbar puncture)

Treatment

There is no known cure for ALS. A medicine called riluzole helps slow down the symptoms and lets you live longer.

Treatments to control other symptoms include:

• Baclofen or diazepam for spasticity that interferes with daily activities
• Trihexyphenidyl or amitriptyline for people with problems swallowing their own saliva

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

Choking is common. Patients may decide to have a tube placed into their stomach for feeding. This is called a gastrostomy.

A nutritionist is very important. Patients with ALS tend to lose weight. The illness itself increases the need for food and calories. At the same time, problems with swallowing make it hard to eat enough.

Breathing devices include machines that are used only at night, and constant mechanical ventilation.

Patients should discuss their wishes regarding artificial ventilation with their families and 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 help people who are coping with the disorder.

Support for people who are caring for someone with ALS is also available, and may be very helpful.

See: ALS - support group

Expectations (prognosis)

Over time, people with ALS progressively lose the ability to function and care for themselves. Death often occurs within 3 - 5 years of diagnosis. About 1 in 4 patients survive for more than 5 years after diagnosis.

Complications

• Breathing in food or fluid (aspiration )
• Loss of ability to care for self
• Lung failure (See: Adult respiratory distress syndrome )
• Pneumonia
• Pressure sores
• Weight loss

Calling your health care provider

Call your health care provider if:

• You have symptoms of ALS, particularly if you have a family history of the disorder
• You or someone else has been diagnosed with ALS and symptoms get worse or new symptoms develop

Increased difficulty swallowing, difficulty breathing, and episodes of apnea are symptoms that require immediate attention.

Prevention

You may want to see a genetic counselor if you have a family history of ALS.

References

Murray B, Mitsumoto H. Disorders of upper and lower motor neurons. In: Daroff RB, Fenichel GM, Jankovic J, eds. Bradley’s Neurology in Clinical Practice. 6th ed. Philadelphia, Pa: Saunders Elsevier; 2012:chap 74.

Shaw PJ. Amyotrophic lateral sclerosis and other motor neuron diseases. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 418.