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{{Short description|Muscular disease in which the muscle fibers do not function correctly}}
{{Infobox Disease |
{{Use dmy dates|date=April 2022}}
Name = Myopathy |
{{Infobox medical condition (new)
Image = |
Caption = | | name = Myopathy
DiseasesDB = 8723 | | image =
| caption =
ICD10 = {{ICD10|G|71||g|70}}-{{ICD10|G|72||g|70}}, {{ICD10|M|60||m|60}}-{{ICD10|M|63||m|60}} |
| field = ], ]
ICD9 = {{ICD9|359.4}}-{{ICD9|359.9}}, {{ICD9|728}}-{{ICD9|728}} |
ICDO = | | symptoms =
| complications =
MedlinePlus = |
| onset =
eMedicineSubj = emerg |
| duration =
eMedicineTopic = 328 |
MeshID = D009135 | | causes =
| risks =
| diagnosis =
| differential =
| prevention =
| treatment =
| medication =
| prognosis =
| frequency =
| deaths =
| synonym = Muscle disease
}} }}
In ], a '''myopathy''' is a muscular ]<ref name="urlMyopathy - Definition from the Merriam-Webster Online Dictionary">{{cite web |url=http://www.merriam-webster.com/dictionary/Myopathy |title=Myopathy - Definition from the Merriam-Webster Online Dictionary |format= |work= |accessdate=}}</ref> in which the ]s do not function for any one of many reasons, resulting in ]. "Myopathy" simply means muscle disease (myo- ] μυο "muscle" + pathos ] ] "suffering"). This meaning implies that the primary defect is within the muscle, as opposed to the nerves ("]" or "]" disorders) or elsewhere (e.g., the brain etc.). ]s, ], and ] can also be associated with myopathy. In ], '''myopathy''' is a ] of the ]<ref name="urlMyopathy - Definition from the Merriam-Webster Online Dictionary">{{cite web |url=http://www.merriam-webster.com/dictionary/Myopathy |title=Myopathy - Definition from the Merriam-Webster Online Dictionary }}</ref> in which the ]s do not function properly. ''Myopathy'' means '''muscle disease''' (] : myo- ''muscle'' + patheia '']'' : ''suffering''). This meaning implies that the primary defect is within the muscle, as opposed to the nerves ("]" or "]" disorders) or elsewhere (e.g., the brain).


This muscular defect typically results in ] (muscle pain), ] (reduced muscle force), or premature ] (initially normal, but declining muscle force). ]s, ], ], and ] can also be associated with myopathy. Myopathy experienced over a long period (chronic) may result in the muscle becoming an abnormal size, such as ] (abnormally small) or a ] (abnormally large).
'''Muscular disease''' can be classified as ] or ] in nature.


Capture myopathy can occur in wild or captive animals, such as deer and ], and leads to morbidity and mortality.<ref>{{cite journal | vauthors = Green-Barber JM, Stannard HJ, Old JM | title = A suspected case of myopathy in a free-ranging eastern grey kangaroo (''Macropus giganteus'') | journal = Australian Mammalogy | volume = 40 | pages = 122–126 | date = 2018 | doi = 10.1071/AM16054 }}</ref> It usually occurs as a result of stress and physical exertion during capture and restraint.
Some conditions, such as ], can be considered both neuromuscular and musculoskeletal.

Muscular disease can be classified as ] or ] in nature. Different myopathies may be inherited, infectious, non-communicable, or idiopathic (cause unknown). The disease may be isolated to affecting only muscle (pure myopathy), or may be part of a systemic disease as is typical in ].

==Signs and symptoms==
Common symptoms include muscle weakness, cramps, stiffness, and ].{{citation needed|date=October 2020}}

== Systemic diseases ==

Myopathies in systemic disease results from several different disease processes including ], ], ], infectious, drug- and toxin-induced, critical illness myopathy, metabolic, ] related,<ref name="pmid19557868">{{cite journal | vauthors = Voermans NC, van Alfen N, Pillen S, Lammens M, Schalkwijk J, Zwarts MJ, van Rooij IA, Hamel BC, van Engelen BG | title = Neuromuscular involvement in various types of Ehlers-Danlos syndrome | journal = Ann. Neurol. | volume = 65 | issue = 6 | pages = 687–97 | date = June 2009 | pmid = 19557868 | doi = 10.1002/ana.21643 | s2cid = 22600065 }}</ref> and myopathies with other systemic disorders. Patients with systemic myopathies often present ] or sub acutely. On the other hand, ] or ] generally present in a ] fashion with exceptions of ] where symptoms on occasion can be precipitated acutely. Metabolic myopathies, which affect the production of ATP within the muscle cell, typically present with ] (exercise-induced) rather than static symptoms.<ref>{{Cite journal |last1=Darras |first1=Basil T. |last2=Friedman |first2=Neil R. |date=February 2000 |title=Metabolic myopathies: a clinical approach; part I |url=https://linkinghub.elsevier.com/retrieve/pii/S0887899499001332 |journal=Pediatric Neurology |language=en |volume=22 |issue=2 |pages=87–97 |doi=10.1016/S0887-8994(99)00133-2|pmid=10738913 }}</ref> Most of the ] can have a chance association with malignant lesion; the incidence appears to be specifically increased only in patients with dermatomyositis.<ref name="pmid21886637">{{cite journal | vauthors = Chawla J | title = Stepwise approach to myopathy in systemic disease | journal = Front Neurol | volume = 2 | pages = 49 | date = 2011 | pmid = 21886637 | pmc = 3153853 | doi = 10.3389/fneur.2011.00049 | doi-access = free }}</ref>


==Classes==
There are many types of myopathy. ] codes are provided here where available. There are many types of myopathy. ] codes are provided here where available.


===Inherited forms===
this disease does not exist
* (G71.0) ] (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 ], and eventually death, usually related to ] weakness.
* (G71.1) ]
** ]
* (G71.2) The ] 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) ] (characterized by presence of "nemaline rods" in the muscle),
** (G71.2) ] (characterized by multiple small "cores" or areas of disruption in the muscle fibers),
** (G71.2) ] (or myotubular myopathy) (in which the ] are abnormally found in the center of the muscle fibers), a rare muscle ] disorder
* (G71.3) ], which are due to defects in ], which provide a critical source of energy for muscle
* (G72.3) Familial ]
* (G72.4) ], which are caused by problems with the immune system attacking components of the muscle, leading to signs of ] in the muscle
* (G73.6) ], which result from defects in biochemical metabolism that primarily affect muscle
** (G73.6/E74.0) ]s, which may affect muscle
** (G73.6/E75) ]
* (G72.89) Other myopathies
** ]
** ]
** ]
** ]
** ]
** ]
** ]


===Acquired=== ===Acquired===
* (G72.0 - G72.2) External substance 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 | vauthors = 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 | date = July 1994 | pmid = 8049126 | doi = 10.1016/0960-0760(94)90165-1 | s2cid = 27814895 }}</ref>
** (G72.1) ]
** (G72.2) Myopathy due to other toxic agents - including ] in ] caused by toxins in ] seeds and seedlings.<ref>{{cite web|url=https://www.rainbowequinehospital.co.uk/information-on-sycamore-poisoning/|title=Information On Sycamore Poisoning|publisher = Rainbow Equine Hospital|access-date=16 May 2017}}</ref><ref>{{cite web|url=http://www.rvc.ac.uk/equine-vet/news/equine-atypical-myopathy-toxin-and-biochemical-tests-and-tree-sample-testing-available-at-the-royal-veterinary-college|title=Equine Atypical Myopathy toxin and biochemical tests and tree sample testing available at the RVC|publisher= Royal Veterinary college - University of London|access-date=16 May 2017|date=13 February 2017}}</ref>
* (M33.0-M33.1) * (M33.0-M33.1)
**] 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) ** ] 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)
**] produces muscle weaknesss. It can often be treated by drugs like corticosteroids or immunosuppressants. ** ] produces muscle weakness. It can often be treated by drugs like corticosteroids or immunosuppressants.
**] is a slowly progressive disease that produces weakness of hand grip and straightening of the knees. No effective treatment is known. ** ] is a slowly progressive disease that produces weakness of hand grip and straightening of the knees. No effective treatment is known.
* (M60.9) ]
* (M61) ] * (M61) ]
* (M62.89) ] and (R82.1) ]s * (M62.89) ] and (R82.1) ]s
The Food and Drug Administration is recommending that physicians restrict prescribing high-dose ] (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.
* Can be caused by '''STATINS'''| Citation:
"Simvastatin 80 mg should not be started in new patients, including patients already taking lower doses of the drug," the agency states.
Glucocorticoid induced myopathy:
* ]
Glucocorticoids whether as endogenous as seen in Cushing's syndrome or exogenously during prolonged glucocorticoid therapy with drugs such as hydrocortrisone, prednisone, methylprednisolone, triamcinolone or dexamethsone cause proximal myopathy. Fluorinated glucocorticois (triamcinolone and prednisone) are more likely to induce myopathy. glucocorticoids affect fast twitch muscle fibers, a group of muscle with the ability of short term anaerobic function. Glucocorticoids affect both synthesis and degradation of muscle fibers. In rats fast twitch type II are affected the most. The degradation is due to increase catabolism of myofibrilar content of the muscle.
Glucocorticoids mediate their catabolic effect through expression of myostatin(1). Myostatin is a member of growth and differentiation family of proteins. Glucocorticoids increase both mRNA and protein expression of myostatin dose dependently. After expression of myostatin by glucocorticoids in the muscle cells (myocytes), it acts both by endocrine (secretion from myocytes to the blood) and paracrine (secrete from myocytes locally and acts on itself) mechanism. Myostatin in turn activates a set of factors in the muscle leading to activation of ubiquitin-proteasome pathway, leading the decline in myosin heavy chain type II. The ubiquitin-proteasome pathway is the protein degradation machinery inside of the cells, and consequently degradation of muscle ensues. In fact knockout mouse with deletion of myostatin gene do not develop glucocorticoid myopathy(2).


===] / ]===
Manifestation of glucocorticoid myopathy are muscle weakness, difficulty to stand up without use of hands and difficulty combing hairs.
* ({{ICD10|I|40||i|30}}) ]
After prolonged period of exposure to glucocorticoids (endogenous or exogenous) severe muscle weakness develops.
* ({{ICD10|I|41||i|30}}) ] in diseases classified elsewhere
Histologically angulation of muscle fibers, Muscle fibers atrophy, and in prolonged cases replacement of muscle fiber by fat can be seen. Absence of inflammatory cells in presence of muscle atrophy is the hallmark of the condition.
* ({{ICD10|I|42||i|30}}) ]
** ({{ICD10|I|42|0|i|30}}) ]
** ({{ICD10|I|42|1|i|30}}) Obstructive ]
** ({{ICD10|I|42|2|i|30}}) Other ]
** ({{ICD10|I|42|3|i|30}}) ] (]) disease
*** ]
*** ]
*** ]
** ({{ICD10|I|42|4|i|30}}) ]
** ({{ICD10|I|42|5|i|30}}) Other ]
** ({{ICD10|I|42|6|i|30}}) ]
** ({{ICD10|I|42|8|i|30}}) Other ]
*** ]
* ({{ICD10|I|43||i|30}}) ] in diseases classified elsewhere


<ref name="The Webs Free 2019 ICD-10-CM/PCS Medical Coding Reference 2018">{{cite web | title=2019 ICD-10-CM Diagnosis Code I42.9: Cardiomyopathy, unspecified | website=The Web's Free 2019 ICD-10-CM/PCS Medical Coding Reference | date=1 October 2018 | url=https://www.icd10data.com/ICD10CM/Codes/I00-I99/I30-I52/I42-/I42.9 | access-date=5 February 2019}}</ref>
There is limited therapeutic trial on drugs that could counteract the effect of glucocorticoids on muscle. Exercise, IGF1, testosterone and glutamine (3) has been shown in animal to decrease the deleterious effect of glucocorticoids, but no randomised trial so far has been done in humans.


===Differential diagnosis===
1)Ma K, Mallidis C, Bhasin S, Mahabadi V, Artaza J, Gonzalez-Cadavid N, Arias J, Salehian B.Glucocorticoid-induced skeletal muscle atrophy is associated with upregulation of myostatin gene expression.Am J Physiol Endocrinol Metab. 2003 Aug;285
3)Salehian B, Mahabadi V, Bilas J, Taylor WE, Ma K. The effect of glutamine on prevention of glucocorticoid-induced skeletal muscle atrophy is associated with myostatin suppression. Metabolism. 2006 Sep;55(9):1239-47.


'''At birth'''''
==Symptoms==
* None as systemic causes; mainly hereditary
*Common muscle weakness. Also (R25.2) ] (M25.6) ], and (R29.0) ]

'''Onset in childhood'''
* Inflammatory myopathies – dermatomyositis, polymyositis (rarely)
* Infectious myopathies
* Endocrine and metabolic disorders – hypokalemia, hypocalcemia, hypercalcemia

'''Onset in adulthood'''<ref name="pmid21886637"/>
* 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== ==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. ], ], bracing for support, ], massage, and even ] are current treatments for a variety of myopathies. 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. ], ], bracing for support, ], and massage are all current treatments for a variety of myopathies.{{citation needed|date=October 2020}}


==References== ==References==
{{reflist}} {{Reflist}}


==External links== ==External links==
*
*See http://neuromuscular.wustl.edu/ for medical descriptions.
* See http://neuromuscular.wustl.edu/ for medical descriptions.


{{Medical conditions}}
{{Diseases of myoneural junction and muscle}} {{Diseases of myoneural junction and muscle}}
{{Systemic connective tissue disorders}} {{Systemic connective tissue disorders}}
{{Myopathy}} {{Myopathy}}
{{Authority control}}


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Latest revision as of 21:10, 19 November 2024

Muscular disease in which the muscle fibers do not function correctly

Medical condition
Myopathy
Other namesMuscle disease
SpecialtyRheumatology, Neuromuscular medicine

In medicine, myopathy is a disease of the muscle in which the muscle fibers do not function properly. Myopathy 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).

This muscular defect typically results in myalgia (muscle pain), muscle weakness (reduced muscle force), or premature muscle fatigue (initially normal, but declining muscle force). Muscle cramps, stiffness, spasm, and contracture can also be associated with myopathy. Myopathy experienced over a long period (chronic) may result in the muscle becoming an abnormal size, such as muscle atrophy (abnormally small) or a pseudoathletic appearance (abnormally large).

Capture myopathy can occur in wild or captive animals, such as deer and kangaroos, and leads to morbidity and mortality. It usually occurs as a result of stress and physical exertion during capture and restraint.

Muscular disease can be classified as neuromuscular or musculoskeletal in nature. Different myopathies may be inherited, infectious, non-communicable, or idiopathic (cause unknown). The disease may be isolated to affecting only muscle (pure myopathy), or may be part of a systemic disease as is typical in mitochondrial myopathies.

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. Metabolic myopathies, which affect the production of ATP within the muscle cell, typically present with dynamic (exercise-induced) rather than static symptoms. Most of the inflammatory myopathies can have a chance association with malignant lesion; 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

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.

Myocardium / cardio-myopathy

Differential diagnosis

At birth

  • 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

  1. "Myopathy - Definition from the Merriam-Webster Online Dictionary".
  2. Green-Barber JM, Stannard HJ, Old JM (2018). "A suspected case of myopathy in a free-ranging eastern grey kangaroo (Macropus giganteus)". Australian Mammalogy. 40: 122–126. doi:10.1071/AM16054.
  3. Voermans NC, van Alfen N, Pillen S, Lammens M, Schalkwijk J, Zwarts MJ, van Rooij IA, Hamel BC, van Engelen BG (June 2009). "Neuromuscular involvement in various types of Ehlers-Danlos syndrome". Ann. Neurol. 65 (6): 687–97. doi:10.1002/ana.21643. PMID 19557868. S2CID 22600065.
  4. Darras, Basil T.; Friedman, Neil R. (February 2000). "Metabolic myopathies: a clinical approach; part I". Pediatric Neurology. 22 (2): 87–97. doi:10.1016/S0887-8994(99)00133-2. PMID 10738913.
  5. ^ Chawla J (2011). "Stepwise approach to myopathy in systemic disease". Front Neurol. 2: 49. doi:10.3389/fneur.2011.00049. PMC 3153853. PMID 21886637.
  6. Seene T (July 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. S2CID 27814895.
  7. "Information On Sycamore Poisoning". Rainbow Equine Hospital. Retrieved 16 May 2017.
  8. "Equine Atypical Myopathy toxin and biochemical tests and tree sample testing available at the RVC". Royal Veterinary college - University of London. 13 February 2017. Retrieved 16 May 2017.
  9. "2019 ICD-10-CM Diagnosis Code I42.9: Cardiomyopathy, unspecified". The Web's Free 2019 ICD-10-CM/PCS Medical Coding Reference. 1 October 2018. Retrieved 5 February 2019.

External links

Diseases of muscle, neuromuscular junction, and neuromuscular disease
Neuromuscular-
junction disease
Myopathy
Muscular dystrophy
(DAPC)
AD
AR
XR
Other structural
Channelopathy
  • (ion channel)
Myotonia
  • Myotonia congenita
  • Neuromyotonia
  • Paramyotonia congenita
    • Periodic paralysis
    Other
    ATPase disorder
    • (ion pump)
  • Brody disease (ATP2A1)
    • Metabolic myopathy
    Endocrinopathy
    General
    Systemic connective tissue disorders
    General
    Systemic lupus erythematosus
    Inflammatory myopathy
    Scleroderma
    Other hypersensitivity/autoimmune
    Other
    Symptoms and conditions relating to muscle
    Pain
    Inflammation
    Destruction
    Low ATP reservoir
    Abnormal movement
    Other
    Category: