Muscle atrophy

Muscular atrophy or muscle wasting, Latin atrophia musculorum, also amyotrophy (from ancient Greek ἀ a "un-", μυς mys "muscle" and τροφή trophie "nourishing"), is defined as a reduction in muscle mass. Most commonly, this form of atrophy occurs when individuals are temporarily prevented from performing everyday movements, such as when immobilized after an injury or hospitalization. Atrophy of a muscle goes hand in hand with muscle weakness, as the strength development of the muscle is directly related to its mass. Modern medicine came to the conclusion that patients should become physically active as soon as possible due to the rapid onset of muscle atrophy during inactivity, despite recent treatment.

Muscular atrophy also accompanies several diseases such as cancer, AIDS, congestive heart failure, chronic lung disease, kidney failure and severe burns. For patients who suffer from cachexia in addition to these diseases, the chances of survival decrease drastically. In addition, malnutrition ultimately leads to muscle atrophy.

The complete inactivity of muscles, as occurs when muscle tissue is immobilised for several days - for example after a bone fracture (plaster cast) - leads to particularly rapid atrophy of inactivity. Keeping this to a minimum is one of the main tasks of physiotherapists, who work in collaboration with hospitals and orthopaedic surgeons. In bone fracture patients with a leg immobilization of three weeks, the atrophy of the back and buttock muscles will be so advanced during rehabilitation that even sitting without assistance will be much more difficult and, moreover, will cause pain, stress and effort, even after only a short period of ten minutes.

Neurogenic atrophy has a similar effect. Damage to nerves that stimulate the muscle lead to this form of atrophy and cause atrophy in an otherwise healthy limb. Furthermore, muscles in microgravity will atrophy after a period of time without exercise. This is partly due to the less effort that must be expended to move.

Symptoms

If everyday movements, such as walking, climbing stairs, cycling or simple household chores are more difficult than usual, this may be due to a lack of or failure to exercise beforehand. The risk of falling or making incorrect movements during such simple movements, in addition to sustaining injuries, increases the longer the period of inactivity. Older people are a particularly vulnerable social group.

Causes

Muscle atrophy can be caused in different ways:

• Dude;
• Malnutrition;
• Inactivity (e.g. due to chronic (joint, back) pain or therapeutic immobility, e.g. due to a plaster cast);
• Disturbance of muscle metabolism;
• Neuromuscular diseases: Failure of those nerves that respond to muscles; these diseases are often genetic (muscular dystrophies);
• Autoimmune diseases - polymyositis, dermatomyositis, inclusion body myositis, interstitial myositis.
• Other wasting diseases such as HIV/Aids and cancer (cachexia)
• Adverse drug reactions (e.g. Levofloxacin)

Due to the reduced strength of the muscles (muscle hypotonia), pain can occur even at low levels of exertion.