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| ==Myopathy in Systemic Diseases== | ==Myopathy in 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, 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.<ref>{{cite |
Myopathies in systemic disease results from several different disease processes including endocrine, inflammatory, paraneoplastic, infectious, drug- and toxin-induced, critical illness myopathy, metabolic, 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.<ref>{{cite journal|last=Chawla|first=Jasvinder|title=Stepwise Approach to Myopathy in Systemic Disease|publisher=Front Neurol. 2011; 2: 49|pmc=3153853|volume=2|pages=49|doi=10.3389/fneur.2011.00049|journal=Frontiers in Neurology|year=2011|pmid=21886637}}</ref> | ||
| ==Classes== | ==Classes== | ||
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| * (G72.0 - G72.2) External substance induced myopathy | * (G72.0 - G72.2) External substance induced myopathy | ||
| ** (G72.0) Drug-induced myopathy | ** (G72.0) Drug-induced myopathy | ||
| *** ] myopathy is caused by this class of steroids ] of the muscle proteins leading to ].<ref name="pmid8049126">{{cite journal |author=Seene T |title=Turnover of skeletal muscle contractile proteins in glucocorticoid myopathy |journal=J. Steroid Biochem. Mol. Biol. |volume=50 |issue= |
*** ] myopathy is caused by this class of steroids ] of the muscle proteins leading to ].<ref name="pmid8049126">{{cite journal |author=Seene T |title=Turnover of skeletal muscle contractile proteins in glucocorticoid myopathy |journal=J. Steroid Biochem. Mol. Biol. |volume=50 |issue=1–2 |pages=1–4 |year=1994 |month=July |pmid=8049126 |doi= 10.1016/0960-0760(94)90165-1|url=}}</ref> | ||
| ** (G72.1) Alcoholic myopathy | ** (G72.1) Alcoholic myopathy | ||
| ** (G72.2) Myopathy due to other toxic agents | ** (G72.2) Myopathy due to other toxic agents | ||
| Line 53: | Line 53: | ||
| "Simvastatin 80 mg should not be started in new patients, including patients already taking lower doses of the drug," the agency states. | "Simvastatin 80 mg should not be started in new patients, including patients already taking lower doses of the drug," the agency states. | ||
| ===Differential diagnosis of systemic myopathy based on age of onset<ref>{{cite |
===Differential diagnosis of systemic myopathy based on age of onset<ref>{{cite journal|first=Myopathy|title=Sytemic Myopathy|pmc=3153853|last1=Chawla|volume=2|pages=49|doi=10.3389/fneur.2011.00049|journal=Frontiers in Neurology|year=2011|pmid=21886637}}</ref> === | ||
| '''Myopathies presenting at birth''':- None as systemic causes; mainly hereditary | '''Myopathies presenting at birth''':- None as systemic causes; mainly hereditary | ||
Revision as of 12:00, 22 May 2013
Medical condition| Myopathy | |
|---|---|
| Specialty | Rheumatology  |
In medicine, a myopathy is a muscular disease in which the muscle fibers do not function for any one of many reasons, resulting in muscular weakness. "Myopathy" simply means muscle disease (myo- Greek μυο "muscle" + pathos -pathy Greek "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 etc.). 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.
Myopathy in 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, 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.
Classes
There are many types of myopathy. ICD-10 codes are provided here where available.
Inherited forms
- (G71.0) Dystrophies (or muscular dystrophies) are a subgroup of myopathies characterized by muscle degeneration and regeneration. Clinically, muscular dystrophies are typically progressive, because the muscles' ability to regenerate is eventually lost, leading to progressive weakness, often leading to use of a wheelchair, and eventually death, usually related to respiratory weakness.
- (G71.1) Myotonia
- (G71.2) The congenital myopathies do not show evidence for either a progressive dystrophic process (i.e., muscle death) or inflammation, but instead characteristic microscopic changes are seen in association with reduced contractile ability of the muscles. Congenital myopathies include, but are not limited to:
- (G71.2) nemaline myopathy (characterized by presence of "nemaline rods" in the muscle),
- (G71.2) multi/minicore myopathy (characterized by multiple small "cores" or areas of disruption in the muscle fibers),
- (G71.2) centronuclear myopathy (or myotubular myopathy) (in which the nuclei are abnormally found in the center of the muscle fibers), a rare muscle wasting disorder
- (G71.3) Mitochondrial myopathies, which are due to defects in mitochondria, which provide a critical source of energy for muscle
- (G72.3) Familial periodic paralysis
- (G72.4) Inflammatory myopathies, which are caused by problems with the immune system attacking components of the muscle, leading to signs of inflammation in the muscle
- (G73.6) Metabolic myopathies, which result from defects in biochemical metabolism that primarily affect muscle
- (G73.6/E74.0) Glycogen storage diseases, which may affect muscle
- (G73.6/E75) Lipid storage disorder
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
- (G72.0) Drug-induced myopathy
- (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 of systemic myopathy based on age of onset
Myopathies presenting at birth:- None as systemic causes; mainly hereditary
Myopathies presenting in childhood:-
Inflammatory myopathies – dermatomyositis, polymyositis (rarely)
Infectious myopathies
Endocrine and metabolic disorders – hypokalemia, hypocalcemia, hypercalcemia
Myopathies presenting 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
Symptoms
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
- "Myopathy - Definition from the Merriam-Webster Online Dictionary".
- Chawla, Jasvinder (2011). "Stepwise Approach to Myopathy in Systemic Disease". Frontiers in Neurology. 2. Front Neurol. 2011; 2: 49: 49. doi:10.3389/fneur.2011.00049. PMC 3153853. PMID 21886637.
{{cite journal}}: CS1 maint: unflagged free DOI (link) - Seene T (1994). "Turnover of skeletal muscle contractile proteins in glucocorticoid myopathy". J. Steroid Biochem. Mol. Biol. 50 (1–2): 1–4. doi:10.1016/0960-0760(94)90165-1. PMID 8049126.
{{cite journal}}: Unknown parameter|month=ignored (help) - Chawla, Myopathy (2011). "Sytemic Myopathy". Frontiers in Neurology. 2: 49. doi:10.3389/fneur.2011.00049. PMC 3153853. PMID 21886637.
{{cite journal}}: CS1 maint: unflagged free DOI (link)
External links
- GeneReviews/NCBI/NIH/UW entry on Myopathy with Deficiency of ISCU
- See http://neuromuscular.wustl.edu/ for medical descriptions.
| Diseases of muscle, neuromuscular junction, and neuromuscular disease | |||||||||||||||||||||||||||
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