Muscle atrophy

Definition:

Muscle atrophy is the wasting or loss of muscle tissue.

Alternative Names:

Muscle wasting; Wasting; Atrophy of the muscles

Considerations:

There are two types of muscle atrophy.

Disuse atrophy occurs from a lack of physical exercise. In most people, muscle atrophy is caused by not using the muscles enough. People with sedentary jobs, medical conditions that limit their movement, or decreased activity levels can lose muscle tone and develop atrophy. This type of atrophy can be reversed with vigorous exercise or better nutrition.

Bedridden people can have significant muscle wasting. Astronauts who are away from the Earth's gravity can develop decreased muscle tone and lose calcium from their bones after just a few days of weightlessness.

The most severe type of muscle atrophy is neurogenic atrophy. It occurs when there is an injury to, or disease of a nerve. This type of muscle atrophy tends to occur more suddenly than disuse atrophy.

Examples of diseases affecting the nerves that control muscles:

Amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease)
Guillain-Barre syndrome
Polio (poliomyelitis)

Even minor muscle atrophy usually causes some loss of movement or strength.

Common Causes:

Some muscle atrophy occurs normally with aging. Other causes may include:

Amyotrophic lateral sclerosis (ALS or Lou Gehrig's disease)
Burns
Guillain-Barre syndrome
Injury
Long-term corticosteroid therapy
Long-term immobilization
Motor neuropathy (such as diabetic neuropathy)
Muscular dystrophy
Osteoarthritis
Polio
Rheumatoid arthritis
Spinal cord injury
Starvation
Stroke

Home Care:

An exercise program (under the direction of a therapist or doctor) is recommended. This may include exercises in water to reduce the muscle workload, and other types of rehabilitation.

People who cannot actively move one or more joints can do exercises using braces or splints.

Call your health care provider if:

Call your doctor for an appointment if you have unexplained or long-term muscle loss. You can often see this when you compare one hand, arm, or leg to the other.

What to expect at your health care provider's office:

The doctor will perform a physical examination and ask questions about your medical history and symptoms, including:

When did the muscle atrophy begin?
Is it getting worse?
What other symptoms do you have?

The doctor will look at your arms and legs and measure muscle size to try to determine which nerve or nerves are affected.

Tests that may be performed include:

Treatment may include ultrasound therapy and, in some cases, surgery to correct a contracture.

References:

Arend WP, Lawry GV. Approach to the patient with rheumatic disease. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier; 2007: chap 277.