Muscle atrophy is when muscles waste away. The main reason for muscle wasting is a lack of physical activity. This can happen when a disease or injury makes it difficult or impossible for you to move an arm or leg.
You may have muscle loss if one of your limbs appears smaller (not shorter) than the other. Schedule a physical exam to determine the cause of the loss. Your doctor will determine what treatment you need. In some cases, muscle wasting can be reversed with a proper diet, exercise, or physical therapy.
Causes of Muscle Atrophy
Unused muscles can waste away if you are not active. However, this takes time. Even after it begins, this type of atrophy can often be reversed with exercise and improved nutrition.
Muscle atrophy can also happen if you are bedridden or unable to move certain body parts due to a medical condition. Astronauts are subject to some muscle atrophy after a few days of weightlessness.
Other causes for muscle atrophy include:
lack of physical activity (for any reason)
alcohol-associated myopathy (pain and weakness in muscles due to excessive drinking over long periods of time)
injuries and broken bones
spinal cord injuries
long-term corticosteroid therapy
Diseases can cause muscles to waste away or can make movement difficult, leading to muscle atrophy. These include:
amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig’s disease), which affects nerve cells that control voluntary muscle movement
dermatomyositis (a muscle disease)
Guillain-Barre syndrome (an autoimmune disease that leads to nerve inflammation and muscle weakness)
multiple sclerosis (MS, an autoimmune disease that can make it difficult to move)
muscular dystrophy (an inherited disease that causes muscle weakness)
neuropathy (damage to a nerve or nerve group, resulting in loss of sensation or function)
osteoarthritis (the most common form of arthritis; causes reduced motion in the joints)
polio (a viral disease affecting muscle tissue that can lead to paralysis)
polymyositis (an inflammatory disease)
rheumatoid arthritis (an autoimmune disease)
spinal muscular atrophy (SMA, a hereditary disease causing arm and leg muscles to waste away)
Signs of Muscle Atrophy
You may have muscle atrophy if:
one of your arms or legs is noticeably smaller than the other
you are experiencing marked weakness in one limb
you have been physically inactive
Contact your doctor to have a complete medical examination if you believe you may have muscle atrophy or if you are unable to move in a normal manner. You may have an undiagnosed condition that requires treatment. Your doctor will be able to provide you with dietary and exercise options.
How Muscle Atrophy Is Diagnosed
Your doctor will take a complete medical history and to understand all of your symptoms. Tell him or her about old or recent injuries you’ve experienced and previously diagnosed medical conditions. List prescriptions, over-the counter medications, and supplements you are taking and your symptoms.
Your doctor may order additional tests to help with the diagnosis and to rule out certain diseases. These tests may include:
magnetic resonance imaging (MRI)
computed tomography (CT) scan
nerve conduction studies
muscle or nerve biopsy
Your doctor may refer you to a specialist depending on the results of these tests.
How Muscle Atrophy Is Treated
Treatment will depend on the diagnosis and the severity of your muscle loss. Any underlying medical conditions must be addressed. Common treatments for muscle atrophy include:
Exercise includes water exercises that are helpful if you have difficulty moving.
Physical therapists can teach you the correct ways to exercise. A physical therapist can move your arms and legs for you if you have trouble moving because of a medical condition.
Ultrasound therapy is a noninvasive procedure that uses sound waves to aid in healing.
Surgery may be necessary if your tendons, ligaments, skin, or muscles are too tight and prevent you from moving. This condition is called contracture deformity. Surgery may be able to correct it if your muscle atrophy is due to malnutrition.
Your doctor will advise you about proper nutrition and suggest proper dietary supplements if he or she believes they are necessary for you.
Written by Ann Pietrangelo
Medically Reviewed by George Krucik, MD
Muscle atrophy. (2012, February 5). National Library of Medicine – National Institutes of Health. Retrieved July 3, 2012, from http://www.nlm.nih.gov/medlineplus/ency/article/003188.htm
NINDS Spinal Muscular Atrophy Information Page. (2011, August). National Institute of Neurological Disorders and Stroke. Retrieved July 3, 2012, from http://www.ninds.nih.gov/disorders/sma/sma.htm
Types of Muscular Dystrophy and Neuromuscular Diseases. (n.d.). Johns Hopkins Medicine Health Library. Retrieved July 3, 2012, from http://www.hopkinsmedicine.org/healthlibrary/conditions/adult/nervous_system_disorders/types_of_muscular_dystrophy_and_neuromuscular_diseases_85,P00792/