Definition

Muscular diseases are attacking muscle cells so that the force is weakened. Women, men and children of all ages can be attacked. The different muscle diseases are distinguished by different symptoms, examination findings, treatment and prognosis. Muscle diseases are distinguished from nerve diseases which can also lead to reduced muscle function, but the cause is damage to the nerves that are supposed to activate the muscles. Examples of such nerve diseases are Multiple sclerosis (MS), Myastenia gravis, Amyotrophic lateral sclerosis (ALS) and Parkinson's disease. Chronic muscle pain that persists for months does not have to be an expression of muscle disease. Fibromyalgia is such a condition that causes a lot of pain and stiffness in almost all muscles in women. In older people can Polymyalgia rheumatica cause sudden, severe pain and stiffness with concomitant signs of inflammation (please see below on this page). Gradually increasing stiffness, muscle pain and other rheumatic ailments can be part of the normal aging process. Please read more about aging and rheumatic symptoms here.

Different muscle disease

• Hereditary Muscular dystrophies are discussed on separate pages, please read more here .
• Electrolyte disturbances (salts) with too high or too low levels of potassium, calcium, or magnesium in the blood and tissues can occur in many diseases and kidney or muscle damage or as a side effect of medications, especially diuretics and some types of blood pressure medications.
• Fibromyalgia causes chronic muscle pain. The triggering cause, however, is primarily not found in the muscles. Please read more about fibromyalgia here
• Infections (viruses, bacteria, parasites) can cause acute and sometimes severe muscle pain.
• Cancer is unusual in muscles, but sarcomas which can occur in different types of connective tissue can also attack muscles.
• Drugs like cholesterol lowering Statins sometimes cause muscle disease
• Mitochondria ("Cell power plant") may be affected (mitochondrion disease). There is often a hereditary cause.
• Muscular overload, poisoning or physical injury to muscles may trigger rhabdomyolysis in which large amounts of muscle cells are suddenly injured
• Myositis with rheumatic inflammation of the muscle cells (inflammatory myopathies) is discussed in more detail here
• Polymyalgia rheumatica people are affected by the age over 50. The reason for rapidly developing stiffness and pain is unknown, but one finds inflammations in joints and tendon attachments outside the muscles themselves. More about polymyalgia rheumatica here .
• Rhabdomyolysis is serious muscle damage that can often be due to hard physical exercise, crushing or squeezing damage to muscles, poisoning, reactions to drugs, intoxicants and more.
• Metabolism
  • Hypothyroidism with more: Too low or too high values ​​of some hormones give typical muscle symptoms (endocrine myopathy) that are seen in endocrine diseases. An example is with too low thyroid function («Low metabolism» hypothyroidism).
  • Metabolic diseases that storage diseases glycogenosis, lipidosis diseases causes too much storage of glycogen or lipids in the muscles.

Examinations

Medical history is important to distinguish different types of muscle disease. Muscle disease in the immediate family, age at onset of symptoms, rapid (days) or slow (weeks-years) development are important. Prior travel abroad, injury, hard training, medication and alcohol intake are also important information.

Ved survey assess whether the muscles are of normal size and strength, whether they are painful or tight. Symptoms from other organs are also examined.

In blood tests er creatine kinase (CK) elevated by polymyositis, Dermatomyositis, Muscular Dystrophy and especially by rhabdomyolysis. CK is a enzyme which originates from muscle cells. The higher the rash in the CK, the more widespread muscle damage must be assumed to be present. After physical exercise and a similar load, the values ​​also rise, but they then return to normal after a few days. Electrolyte and hormone disorders are also detected in blood tests. By Fibromyalgia og Polymyalgia rheumatica is CK normal. In myositis, rashes are often also seen antinuclear antibody (ANA) and associated subgroups are often found. In some cases, these subgroups may indicate an increased risk of developing special complications. An example is the anti-Jo-1 antibody, which requires further lung examinations. On suspicion of heredity Muscular Dystrophy or metabolic muscle diseases / storage diseases, genetic assessment and associated tests are performed

Imaging. MRI examination of affected muscles can help to distinguish the various muscle diseases. In addition, MRI changes can locate areas where it is appropriate to take a tissue sample (biopsy) from. CT of the lungs may be relevant if concomitant lung manifestations are suspected.

Vev sample (biopsy) from the attacked muscle is always an important examination in the investigation of serious muscle disease. By microscopic examination and other tests via the tissue sample, hereditary myopathies can be distinguished from myositis, rhabdomyolysis and metabolic muscle diseases.

Other investigations: Wood electromyography (EMG) og neurography Signals from muscles and nerves may show different responses, depending on the underlying cause of the disease, but the tests alone are not sufficient to make a definite diagnosis.

Similar conditions, differential diagnoses

• Fibromyalgia og myalgia (muscle pain) are pain in muscles that reduce function, but without inflammation or other disease in the muscle cells. Women are most commonly affected
• Polymyalgia rheumatica attacks older people (often over 65 years of age). There are clear results in inflammation tests, but not in the muscle cells themselves
• Disease of the nervous system, which results in reduced muscle function occur in
  • Multiple Sclerosis (MS)
  • Myastenia gravis
  • Amyotrophic lateral sclerosis (ALS)
  • Parkinson's disease

Treatment

To provide proper treatment, diagnosis of type of muscle disease is essential. The treatment is described under the individual diagnoses.

Prognosis

The prognosis are very different between the various diseases, in part, also depending on the response and tolerance of the treatment. For more information, see articles about the different diseases.

Specialists

Hereditary muscular dystrophies are usually investigated and treated by specialists in pediatric diseases or in adulthood by neurologists. Myositis is in the field of rheumatology. Metabolic and hormonally induced muscle diseases are most often managed by endocrinologists. Other muscle diseases and pain conditions are assessed and followed by other specialists or general practitioners, depending on the severity. If necessary, close collaboration between specialist, GP, possibly other therapists and the patient is always important.

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