medicine Medicine is the science and Praxis (process), practice of caring for patients, managing the Medical diagnosis, diagnosis, prognosis, Preventive medicine, prevention, therapy, treatment, Palliative care, palliation of their injury or disease, ...

, myopathy is a

disease A disease is a particular abnormal condition that adversely affects the structure or function (biology), function of all or part of an organism and is not immediately due to any external injury. Diseases are often known to be medical condi ...

of the

muscle Muscle is a soft tissue, one of the four basic types of animal tissue. There are three types of muscle tissue in vertebrates: skeletal muscle, cardiac muscle, and smooth muscle. Muscle tissue gives skeletal muscles the ability to muscle contra ...

in which the

muscle fiber A muscle cell, also known as a myocyte, is a mature contractile cell in the muscle of an animal. In humans and other vertebrates there are three types: skeletal, smooth, and cardiac (cardiomyocytes). A skeletal muscle cell is long and threadl ...

s do not function properly. ''Myopathy'' means muscle disease (

Greek Greek may refer to: Anything of, from, or related to Greece, a country in Southern Europe: *Greeks, an ethnic group *Greek language, a branch of the Indo-European language family **Proto-Greek language, the assumed last common ancestor of all kno ...

: myo- ''muscle'' + patheia '' -pathy'' : ''suffering''). This meaning implies that the primary defect is within the muscle, as opposed to the nerves ("

neuropathies Peripheral neuropathy, often shortened to neuropathy, refers to damage or disease affecting the nerves. Damage to nerves may impair sensation, movement, gland function, and/or organ function depending on which nerve fibers are affected. Neuropa ...

" or "

neurogenic In biology, the nervous system is the highly complex part of an animal that coordinates its actions and sensory information by transmitting signals to and from different parts of its body. The nervous system detects environmental changes t ...

" disorders) or elsewhere (e.g., the brain). This muscular defect typically results in

myalgia Myalgia or muscle pain is a painful sensation evolving from muscle tissue. It is a symptom of many diseases. The most common cause of acute myalgia is the overuse of a muscle or group of muscles; another likely cause is viral infection, espec ...

(muscle pain),

muscle weakness Muscle weakness is a lack of muscle strength. Its causes are many and can be divided into conditions that have either true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, includ ...

(reduced muscle force), or premature

muscle fatigue Muscle fatigue is when muscles that were initially generating a normal amount of force, then experience a declining ability to generate force. It can be a result of vigorous exercise, but abnormal fatigue may be caused by barriers to or interfer ...

(initially normal, but declining muscle force).

Muscle cramp A cramp is a sudden, involuntary, painful skeletal muscle contraction or overshortening associated with electrical activity. While generally temporary and non-damaging, they can cause significant pain and a paralysis-like immobility of the affe ...

stiffness Stiffness is the extent to which an object resists deformation in response to an applied force. The complementary concept is flexibility or pliability: the more flexible an object is, the less stiff it is. Calculations The stiffness, k, of a ...

spasm A spasm is a sudden involuntary contraction of a muscle, a group of muscles, or a hollow organ, such as the bladder. A spasmodic muscle contraction may be caused by many medical conditions, including dystonia. Most commonly, it is a musc ...

, and

contracture In pathology, a contracture is a shortening of muscles, tendons, skin, and nearby soft tissues that causes the joints to shorten and become very stiff, preventing normal movement. A contracture is usually permanent, but less commonly can be temp ...

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 Muscle atrophy is the loss of skeletal muscle mass. It can be caused by immobility, aging, malnutrition, medications, or a wide range of injuries or diseases that impact the musculoskeletal or nervous system. Muscle atrophy leads to muscle weakne ...

(abnormally small) or a

pseudoathletic appearance Pseudoathletic appearance is a medical sign meaning to have the false appearance of a well-trained athlete due to pathologic causes (disease or injury) instead of true athleticism. It is also referred to as a Herculean or bodybuilder-like ap ...

(abnormally large). Capture myopathy can occur in wild or captive animals, such as deer and

kangaroos Kangaroos are marsupials from the family Macropodidae (macropods, meaning "large foot"). In common use, the term is used to describe the largest species from this family, the red kangaroo, as well as the antilopine kangaroo, eastern grey ...

, 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 A neuromuscular junction (or myoneural junction) is a chemical synapse between a motor neuron and a muscle fiber. It allows the motor neuron to transmit a signal to the muscle fiber, causing muscle contraction. Muscles require innervation to ...

musculoskeletal The human musculoskeletal system (also known as the human locomotor system, and previously the activity system) is an organ system that gives humans the ability to move using their muscular and skeletal systems. The musculoskeletal system provid ...

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 The endocrine system is a messenger system in an organism comprising feedback loops of hormones that are released by internal glands directly into the circulatory system and that target and regulate distant organs. In vertebrates, the hypotha ...

, inflammatory, paraneoplastic, infectious, drug- and toxin-induced, critical illness myopathy, metabolic,

collagen Collagen () is the main structural protein in the extracellular matrix of the connective tissues of many animals. It is the most abundant protein in mammals, making up 25% to 35% of protein content. Amino acids are bound together to form a trip ...

related, and myopathies with other systemic disorders. Patients with systemic myopathies often present acutely or subacutely. 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 ICD-10 is the 10th revision of the International Classification of Diseases (ICD), a medical classification list by the World Health Organization (WHO). It contains codes for diseases, signs and symptoms, abnormal findings, complaints, social cir ...

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 and often leading to use of a

wheelchair A wheelchair is a mobilized form of chair using two or more wheels, a footrest, and an armrest usually cushioned. It is used when walking is difficult or impossible to do due to illnesses, injury, disabilities, or age-related health conditio ...

and eventually death, usually related to

respiratory The respiratory system (also respiratory apparatus, ventilatory system) is a biological system consisting of specific organs and structures used for gas exchange in animals and plants. The anatomy and physiology that make this happen varies gr ...

weakness. * (G71.1)

Myotonia Myotonia is a symptom of a small handful of certain neuromuscular disorders characterized by delayed relaxation (prolonged contraction) of the skeletal muscles after voluntary contraction or electrical stimulation, and the muscle shows an abnor ...

Neuromyotonia Neuromyotonia (NMT) is a form of peripheral nerve hyperexcitability that causes spontaneous muscular activity resulting from repetitive motor unit action potentials of peripheral origin. NMT along with Morvan's syndrome are the most severe types ...

* (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 Nemaline myopathy (also called rod myopathy or nemaline rod myopathy) is a congenital, often hereditary neuromuscular disorder with many symptoms that can occur such as muscle weakness, hypoventilation, swallowing dysfunction, and impaired speech ...

(characterized by presence of "nemaline rods" in the muscle), ** (G71.2)

multi/minicore myopathy Multi/minicore myopathy is a congenital myopathy usually caused by mutations in either the ''SELENON'' and ''RYR1'' genes. It is characterised the presence of multifocal, well-circumscribed areas with reduction of oxidative staining and low myofib ...

(characterized by multiple small "cores" or areas of disruption in the muscle fibers), ** (G71.2)

centronuclear myopathy Centronuclear myopathies (CNM) are a group of congenital myopathies where cell nuclei are abnormally located in the center of muscle cells instead of their normal location at the periphery. Symptoms of CNM include severe hypotonia, hypoxia-req ...

(or myotubular myopathy) (in which the nuclei are abnormally found in the center of the muscle fibers), a rare muscle

wasting In medicine, wasting, also known as wasting syndrome, refers to the process by which a debilitating disease causes muscle and fat tissue to "waste" away. Wasting is sometimes referred to as "acute malnutrition" because it is believed that epis ...

disorder. * (G71.3) Mitochondrial myopathies, which are due to defects in

mitochondria A mitochondrion () is an organelle found in the cells of most eukaryotes, such as animals, plants and fungi. Mitochondria have a double membrane structure and use aerobic respiration to generate adenosine triphosphate (ATP), which is us ...

, which provide a critical source of energy for muscle * (G72.3) Familial

periodic paralysis Periodic paralysis is a group of rare genetic diseases that lead to weakness or paralysis from common triggers such as cold, heat, high carbohydrate meals, not eating, stress or excitement and physical activity of any kind. The underlying mechani ...

* (G72.4) Inflammatory myopathies, which are caused by problems with the immune system attacking components of the muscle, leading to signs of

inflammation Inflammation (from ) is part of the biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. The five cardinal signs are heat, pain, redness, swelling, and loss of function (Latin ''calor'', '' ...

in the muscle * (G73.6) Metabolic myopathies, which result from defects in biochemical metabolism that primarily affect muscle ** (G73.6/E74.0)

Glycogen storage disease A glycogen storage disease (GSD, also glycogenosis and dextrinosis) is a metabolic disorder caused by a deficiency of an enzyme or transport protein affecting glycogen synthesis, glycogen breakdown, or glycolysis, glucose breakdown, typically in m ...

s, which may affect muscle ** (G73.6/E75) Lipid storage disorder * (G72.89) Other myopathies ** Brody myopathy ** Congenital myopathy with abnormal subcellular organelles ** Fingerprint body myopathy ** Inclusion body myopathy 2 ** Megaconial myopathy ** Myofibrillar myopathy ** Rimmed vacuolar myopathy

Acquired

* (G72.0 - G72.2) External substance induced myopathy ** (G72.0) Drug-induced myopathy ***

Glucocorticoid Glucocorticoids (or, less commonly, glucocorticosteroids) are a class of corticosteroids, which are a class of steroid hormones. Glucocorticoids are corticosteroids that bind to the glucocorticoid receptor that is present in almost every vertebra ...

myopathy is caused by this class of steroids increasing the breakdown of the muscle proteins leading to

. ** (G72.1) Alcoholic myopathy ** (G72.2) Myopathy due to other toxic agents, including atypical myopathy in

horses The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 milli ...

caused by toxins in

sycamore Sycamore is a name which has been applied to several types of trees, but with somewhat similar leaf forms. The name derives from the Ancient Greek () meaning . Species of otherwise unrelated trees known as sycamore: * ''Acer pseudoplatanus'', a ...

seeds and seedlings. * (M33.0-M33.1) **

Dermatomyositis Dermatomyositis (DM) is a Chronic condition, long-term inflammatory disorder, inflammatory Autoimmune disease, autoimmune disorder which affects the skin and the muscles. Its symptoms are generally a skin rash and worsening muscle weakness over ...

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 Polymyositis (PM) is a type of chronic inflammation of the muscles ( inflammatory myopathy) related to dermatomyositis and inclusion body myositis. Its name is derived . The inflammation of polymyositis is mainly found in the endomysial layer ...

produces muscle weakness. It can often be treated by drugs like corticosteroids or immunosuppressants. **

Inclusion body myositis Inclusion body myositis (IBM) () (sometimes called sporadic inclusion body myositis, sIBM) is the most common inflammatory muscle disease in older adults. The disease is characterized by slowly progressive weakness and wasting of both proximal m ...

is a slowly progressive disease that produces weakness of hand grip and straightening of the knees. No effective treatment is known. * (M60.9)

Benign acute childhood myositis Benign acute childhood myositis (BACM) is a syndrome characterized by muscle weakness and pain in the lower limbs that develop in children after a recent viral illness. It is transient with a spontaneous clinical resolution within 1 week. Symptoms ...

* (M61)

Myositis ossificans Myositis ossificans comprises two syndromes characterized by heterotopic ossification (calcification) of muscle. In 2020, the World Health Organization classified myositis ossificans together with fibro-osseous pseudotumor of digits as a single sp ...

* (M62.89)

Rhabdomyolysis Rhabdomyolysis (shortened as rhabdo) is a condition in which damaged skeletal muscle breaks down rapidly. Symptoms may include muscle pains, weakness, vomiting, and confusion. There may be tea-colored urine or an irregular heartbeat. Some o ...

and (R82.1)

myoglobinuria Myoglobinuria is the presence of myoglobin in the urine, which usually results from rhabdomyolysis or muscle injury. Myoglobin is present in muscle cells as a reserve of oxygen. Signs and symptoms Signs and symptoms of myoglobinuria are usua ...

s The Food and Drug Administration is recommending that physicians restrict prescribing high-dose

Simvastatin Simvastatin, sold under the brand name Zocor among others, is a statin, a type of lipid-lowering medication. It is used along with exercise, diet, and weight loss to decrease hyperlipidemia, elevated lipid levels. It is also used to decrease t ...

(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. * Statin-associated autoimmune myopathy

Myocardium Cardiac muscle (also called heart muscle or myocardium) is one of three types of vertebrate muscle tissues, the others being skeletal muscle and smooth muscle. It is an involuntary, striated muscle that constitutes the main tissue of the wall o ...
/
cardiomyopathy Cardiomyopathy is a group of primary diseases of the heart muscle. Early on there may be few or no symptoms. As the disease worsens, shortness of breath, feeling tired, and swelling of the legs may occur, due to the onset of heart failure. A ...

* () Acute myocarditis * ()

Myocarditis Myocarditis is inflammation of the cardiac muscle. Myocarditis can progress to inflammatory cardiomyopathy when there is associated ventricular remodeling and cardiac dysfunction due to chronic inflammation. Symptoms can include shortness of bre ...

in diseases classified elsewhere * ()

Cardiomyopathy Cardiomyopathy is a group of primary diseases of the heart muscle. Early on there may be few or no symptoms. As the disease worsens, shortness of breath, feeling tired, and swelling of the legs may occur, due to the onset of heart failure. A ...

** ()

Dilated cardiomyopathy Dilated cardiomyopathy (DCM) is a condition in which the heart becomes enlarged and cannot pump blood effectively. Symptoms vary from none to feeling tired, leg swelling, and shortness of breath. It may also result in chest pain or fainting. C ...

** () Obstructive hypertrophy cardiomyopathy ** () Other

hypertrophic cardiomyopathy Hypertrophic cardiomyopathy (HCM, or HOCM when obstructive) is a condition in which muscle tissues of the heart become thickened without an obvious cause. The parts of the heart most commonly affected are the interventricular septum and the ...

** () Endomyocardial (

eosinophilic Eosinophilic (Greek suffix '' -phil'', meaning ''eosin-loving'') describes the staining of tissues, cells, or organelles after they have been washed with eosin, a dye commonly used in histological staining. Eosin is an acidic dye for stainin ...

) disease ***

Eosinophilic myocarditis Eosinophilic myocarditis is inflammation in the Myocardium, heart muscle that is caused by the infiltration and destructive activity of a type of white blood cell, the eosinophil. Typically, the disorder is associated with hypereosinophilia, i.e. a ...

*** Endomyocardial (tropical) fibrosis *** Löffler's endocarditis ** ()

Endocardial fibroelastosis Endocardial fibroelastosis (EFE) is a rare heart disorder usually occurring in children two years old and younger. It may also be considered a reaction to stress, not necessarily a specific disease. It should not be confused with endomyocardial f ...

** () Other

restrictive cardiomyopathy Restrictive cardiomyopathy (RCM) is a form of cardiomyopathy in which the walls of the heart are rigid (but not thickened). Thus the heart is restricted from stretching and filling with blood properly. It is the least common of the three original s ...

** ()

Alcoholic cardiomyopathy Alcoholic cardiomyopathy (ACM) is a disease in which the long-term consumption of alcohol (drug), alcohol leads to heart failure. ACM is a type of dilated cardiomyopathy. The heart is unable to pump blood efficiently, leading to heart failure. It ...

** () Other

cardiomyopathies Cardiomyopathy is a group of primary diseases of the heart muscle. Early on there may be few or no symptoms. As the disease worsens, shortness of breath, feeling tired, and swelling of the legs may occur, due to the onset of heart failure. An ...

***

Arrhythmogenic right ventricular dysplasia Arrhythmogenic cardiomyopathy (ACM) is an inherited heart disease. ACM is caused by genetic defects of parts of the cardiac muscle known as desmosomes, areas on the surface of muscle cells which link them together. The desmosomes are composed ...

* ()

in diseases classified elsewhere

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 Physical therapy (PT), also known as physiotherapy, is a healthcare profession, as well as the care provided by physical therapists who promote, maintain, or restore health through patient education, physical intervention, disease preventio ...

, bracing for support,

surgery Surgery is a medical specialty that uses manual and instrumental techniques to diagnose or treat pathological conditions (e.g., trauma, disease, injury, malignancy), to alter bodily functions (e.g., malabsorption created by bariatric surgery s ...

, and massage are all current treatments for a variety of myopathies.

References

External links

GeneReviews/NCBI/NIH/UW entry on Myopathy with Deficiency of ISCU
* See http://neuromuscular.wustl.edu/ for medical descriptions. {{Authority control Muscular disorders