| Myopathy |
| Classification and external resources |
| Specialty |
Rheumatology |
| ICD-10 |
G71-G72, M60-M63 |
| ICD-9-CM |
359.4-359.9, 728-728 |
| DiseasesDB |
8723 |
| eMedicine |
emerg/328 |
| Patient UK |
Myopathy |
| MeSH |
D009135 |
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[edit on Wikidata]
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Myopathy is a disease of muscle[1] 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.
Contents
- 1 Signs and symptoms
- 2 Systemic diseases
- 2.1 Inherited forms
- 2.2 Acquired
- 2.3 Differential diagnosis
- 3 Treatments
- 4 References
- 5 External links
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,[2] 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.[3]
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.[4]
- (G72.1) Alcoholic myopathy
- (G72.2) Myopathy due to other toxic agents
- (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[5]
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
- ^ "Myopathy - Definition from the Merriam-Webster Online Dictionary".
- ^ Voermans NC1, van Alfen N, Pillen S, Lammens M, Schalkwijk J, Zwarts MJ, van Rooij IA, Hamel BC, van Engelen BG. (2009). "Neuromuscular involvement in various types of Ehlers-Danlos syndrome.". Ann Neurol.
- ^ Chawla, Jasvinder (2011). "Stepwise Approach to Myopathy in Systemic Disease". Frontiers in Neurology. Front Neurol. 2011; 2: 49. 2: 49. doi:10.3389/fneur.2011.00049. PMC 3153853. PMID 21886637.
- ^ 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.
- ^ Chawla, Myopathy (2011). "Systemic Myopathy". Frontiers in Neurology. 2: 49. doi:10.3389/fneur.2011.00049. PMC 3153853. PMID 21886637.
External links
- GeneReviews/NCBI/NIH/UW entry on Myopathy with Deficiency of ISCU
- See http://neuromuscular.wustl.edu/ for medical descriptions.
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Diseases of myoneural junction and muscle / neuromuscular disease (G70–G73, 358–359)
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Neuromuscular-
junction disease |
- autoimmune
- Myasthenia gravis
- Lambert–Eaton myasthenic syndrome
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Myopathy/
congenital myopathy |
Muscular dystrophy
(DAPC) |
| AD |
- Limb-girdle muscular dystrophy 1
- Oculopharyngeal
- Facioscapulohumeral
- Myotonic
- Distal (most)
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| AR |
- Limb-girdle muscular dystrophy 2
- Congenital
- Fukuyama
- Ullrich
- Walker–Warburg
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| XR |
- dystrophin
- Emery–Dreifuss
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| Other structural |
- collagen disease
- PTP disease
- adaptor protein disease
- BIN1-linked centronuclear myopathy
- cytoskeleton disease
- Nemaline myopathy
- Zaspopathy
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| Channelopathy |
| Myotonia |
- Myotonia congenita
- Thomsen disease
- Neuromyotonia/Isaacs syndrome
- Paramyotonia congenita
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| Periodic paralysis |
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| Other |
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| Mitochondrial myopathy |
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| Other |
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Systemic connective tissue disorders (M32–M36, 710)
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| General |
| Systemic lupus erythematosus |
- Drug-induced SLE
- Libman–Sacks endocarditis
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| Inflammatory myopathy |
- Myositis
- Dermatopolymyositis
- Dermatomyositis/Juvenile dermatomyositis
- Polymyositis* Inclusion body myositis
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| Scleroderma |
- Systemic scleroderma
- Progressive systemic sclerosis
- CREST syndrome
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- Overlap syndrome / Mixed connective tissue disease
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| Other hypersensitivity/autoimmune |
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| Other |
- Behçet's disease
- Polymyalgia rheumatica
- Eosinophilic fasciitis
- Eosinophilia–myalgia syndrome
- fibrillin
- Marfan syndrome
- Congenital contractural arachnodactyly
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Myopathy (M60–M63, 728.0–3,8)
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| Pain |
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| Inflammation |
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| Lytic |
- Muscle weakness
- Rhabdomyolysis
- Muscle atrophy/Amyotrophy
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| Other |
- Myositis ossificans
- Fibrodysplasia ossificans progressiva
- Compartment syndrome
- Diastasis of muscle
- Muscle spasm
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