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Myopathy

Myopathy is a disease of muscle in which the muscle fibers do not function properly. This results in muscular weakness. "Myopathy" simply means muscle disease ( Greek myo- "muscle" + patheia < -pathy "suffering"). This meaning implies that the primary defect is within the muscle, as opposed to the nerves (" neuropathies" or " neurogenic" disorders) or elsewhere (e.g., the brain). Muscle cramps, stiffness, and spasm can also be associated with myopathy. Muscular disease can be classified as neuromuscular or musculoskeletal in nature. Some conditions, such as myositis, can be considered both neuromuscular and musculoskeletal.

Signs and symptoms

Common symptoms include muscle weakness, cramps, stiffness, and tetany.

Systemic diseases

Myopathies in systemic disease results from several different disease processes including endocrine, inflammatory, paraneoplastic, infectious, drug- and toxin-induced, critical illness myopathy, metabolic, collagen related, and myopathies with other systemic disorders. Patients with systemic myopathies often present acutely or sub acutely. On the other hand, familial myopathies or dystrophies generally present in a chronic fashion with exceptions of metabolic myopathies where symptoms on occasion can be precipitated acutely. Most of the inflammatory myopathies can have a chance association with malignant lesions; the incidence appears to be specifically increased only in patients with dermatomyositis. There are many types of myopathy. ICD-10 codes are provided here where available.

Inherited forms

Acquired

  • (G72.0 - G72.2) External substance induced myopathy
  • * (G72.0) Drug-induced myopathy
  • ** Glucocorticoid myopathy is caused by this class of steroids increasing the breakdown of the muscle proteins leading to muscle atrophy.
  • * (G72.1) Alcoholic myopathy
  • * (G72.2) Myopathy due to other toxic agents - including atypical myopathy in horses caused by toxins in Sycamore seeds and seedlings.
  • (M33.0-M33.1)
  • * Dermatomyositis produces muscle weakness and skin changes. The skin rash is reddish and most commonly occurs on the face, especially around the eyes, and over the knuckles and elbows. Ragged nail folds with visible capillaries can be present. It can often be treated by drugs like corticosteroids or immunosuppressants. (M33.2)
  • * Polymyositis produces muscle weaknesss. It can often be treated by drugs like corticosteroids or immunosuppressants.
  • * Inclusion body myositis is a slowly progressive disease that produces weakness of hand grip and straightening of the knees. No effective treatment is known.
  • (M61) Myositis ossificans
  • (M62.89) Rhabdomyolysis and (R82.1) myoglobinurias
The Food and Drug Administration is recommending that physicians restrict prescribing high-dose Simvastatin (Zocor, Merck) to patients, given an increased risk of muscle damage. The FDA drug safety communication stated that physicians should limit using the 80-mg dose unless the patient has already been taking the drug for 12 months and there is no evidence of myopathy. "Simvastatin 80 mg should not be started in new patients, including patients already taking lower doses of the drug," the agency states.

Differential diagnosis

At DeathMlg '' None as systemic causes; mainly hereditary Onset in childhood Inflammatory myopathies – dermatomyositis, polymyositis (rarely) Infectious myopathies Endocrine and metabolic disorders – hypokalemia, hypocalcemia, hypercalcemia Onset in adulthood Inflammatory myopathies – polymyositis, dermatomyositis, inclusion body myositis, viral (HIV) Infectious myopathies Endocrine myopathies – thyroid, parathyroid, adrenal, pituitary disorders Toxic myopathies – alcohol, corticosteroids, narcotics, colchicines, chloroquine Critical illness myopathy Metabolic myopathies Paraneoplastic myopathy

Treatments

Because different types of myopathies are caused by many different pathways, there is no single treatment for myopathy. Treatments range from treatment of the symptoms to very specific cause-targeting treatments. Drug therapy, physical therapy, bracing for support, surgery, and massage are all current treatments for a variety of myopathies.

References

External links

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This article based upon the http://en.wikipedia.org/wiki/Myopathy, the free encyclopaedia Wikipedia and is licensed under the GNU Free Documentation License.
Further informations available on the list of authors and history: http://en.wikipedia.org/w/index.php?title=Myopathy&action=history
presented by: Ingo Malchow, Mirower Bogen 22, 17235 Neustrelitz, Germany