Muscle Atrophy

Muscle atrophy means loss of muscle tissue.It is a problem accompanying many diseases of muscles and nervous system.

Causes

Muscle inactivity

Insufficient use of muscle related to lifestyle lacking physical activity is common in developed countries. Decreased muscle strength and quick fatigue during exercise is a logical consequence. From the medical point of view, we should mention muscle loss in immobile patients in critical health conditions and after major surgical interventions. For this reason, proper rehabilitation and nutrition should always be a part of recovery period.

Malnutrition

Insufficient supply of nutrients, especially lack of proteins, causes muscle atrophy as proteins are important building material of muscle fibers. In addition, the body needs proteins to preserve biochemical reactions and muscle tissue starts to be degraded. Again, it is important to take this into account in patients in critical condition where the body metabolism has been primarily set to catabolic reactions including muscle breakdown. Together with the immobility this leads to severe muscle atrophy. However, malnutrition does not occur only in people with poor dietary intake but also in patients suffering from impaired absorption of nutrients.

Neurological causes

If certain muscles loose the innervation, they are prone to atrophy. It can be both diseases of central nervous system or peripheral nerves. Central nervous system (neurons in brain and spine) may be affected for example by a stroke, multiple sclerosis, spinal injuries, cerebral palsy, split spine and amyotrophic lateral sclerosis. Peripheral nerves may be damaged by injuries and some forms of polyneuropathic disorders.

Polymyositis

This autoimmune disease is caused by damage of muscle fibers by our own immune system. Muscle weakness with muscle atrophy is a classic symptom.

Corticosteroids

Chronic use of these drugs has a number of unpleasant side effects including muscular atrophy and obesity.

Systemic diseases

A number of serious diseases that affect the entire body result in loss of muscle mass. It is caused by the disease itself or by overall response of the organism. This happens in cancers, AIDS, in severe forms of heart failure and chronic kidney failure.

Congenital diseases

Probably most known inherited disease is the Duchenne muscular dystrophy. It is caused by genetically determined defect of muscle protein dystrophin. The disease is incurable, slowly progresses and is fatal. A similar and somewhat less dangerous variant is called Becker's disease.

Diagnostic approach

Medical history and physical examination is important, it s advisable to examine the patient by a neurologist to evaluate muscle strength and muscle reflexes. It is also possible to perform electromyography to investigate the transmission of neuromuscular signal. Blood test help us to evaluate nutrition parameters and concentration of creatin kinase (CK), which is an enzyme located in muscle fibers. Elevation of creatin kinase serum level marks possible muscle tissue damage (typical in polymyositis). Further examination depends on outcome of previously mentioned diagnostic methods.