medicine Medicine is the science and practice of caring for a patient, managing the diagnosis, prognosis, prevention, treatment, palliation of their injury or disease, and promoting their health. Medicine encompasses a variety of health care pr ...

, myopathy is a

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

of the muscle in which the

muscle fiber A muscle cell is also known as a myocyte when referring to either a cardiac muscle cell (cardiomyocyte), or a smooth muscle cell as these are both small cells. A skeletal muscle cell is long and threadlike with many nuclei and is called a muscl ...

s do not function properly. This results in

muscular weakness Weakness is a symptom of a number of different conditions. The causes are many and can be divided into conditions that have true or perceived muscle weakness. True muscle weakness is a primary symptom of a variety of skeletal muscle diseases, ...

. ''Myopathy'' means muscle disease (

Greek Greek may refer to: Greece 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 ...

: 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, is a general term describing disease affecting the peripheral nerves, meaning nerves beyond the brain and spinal cord. Damage to peripheral nerves may impair sensation, movement, gland, or o ...

" 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 ...

" disorders) or elsewhere (e.g., the brain).

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 aff ...

s, stiffness, and

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 muscle c ...

can also be associated with myopathy. Capture myopathy can occur in wild or captive animals, such as deer and

kangaroos Kangaroos are four 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 gre ...

, 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 ...

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 prov ...

in nature. Some conditions, such as

myositis Myositis is a rare disease that involves inflammation of the muscles. This can present with a variety of symptoms such as skin involvement (i.e., rashes), muscle weakness, and other organ involvement. Systemic symptoms such as weight loss, fatigue ...

, can be considered both neuromuscular and musculoskeletal.

Signs and symptoms

Common symptoms include muscle weakness,

cramps 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 aff ...

, 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 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

* (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 A wheelchair is a chair with wheels, used when walking is difficult or impossible due to illness, injury, problems related to old age, or disability. These can include spinal cord injuries ( paraplegia, hemiplegia, and quadriplegia), cerebr ...

, 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 gre ...

weakness. * (G71.1) Myotonia ** Neuromyotonia * (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 ''SEPN1'' and ''RYR1'' genes. It is characterised the presence of multifocal, well-circumscribed areas with reduction of oxidative staining and low myofibri ...

(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-requi ...

(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 Mitochondrial myopathies are types of myopathies associated with mitochondrial disease. On biopsy, the muscle tissue of patients with these diseases usually demonstrate "ragged red" muscle fibers. These ragged-red fibers contain mild accumulation ...

, which are due to defects in mitochondria, 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 mechanis ...

* (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 la, inflammatio) is part of the complex biological response of body tissues to harmful stimuli, such as pathogens, damaged cells, or irritants, and is a protective response involving immune cells, blood vessels, and molec ...

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 * (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 verteb ...

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 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 ' (''sūkomoros'') meaning "fig-mulberry". Species of trees known as sycamore: * ''Acer pseudoplata ...

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

Dermatomyositis Dermatomyositis (DM) is a long-term inflammatory disorder which affects skin and the muscles. Its symptoms are generally a skin rash and worsening muscle weakness over time. These may occur suddenly or develop over months. Other symptoms may inc ...

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 means "inflammation of many muscles" ('' poly-'' + '' myos-'' + '' -itis''). The inflam ...

produces muscle weakness. 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)

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 us ...

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 elevated lipid levels. It is also used to decrease the risk of hear ...

(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 / cardio-myopathy

* () Acute myocarditis * () Myocarditis in diseases classified elsewhere * () Cardiomyopathy ** ()

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. Co ...

** () Obstructive hypertrophy cardiomyopathy ** () Other hypertrophic cardiomyopathy ** () Endomyocardial (

eosinophilic Eosinophilic (Greek suffix -phil-, meaning ''loves eosin'') is the staining of tissues, cells, or organelles after they have been washed with eosin, a dye. Eosin is an acidic dye for staining cell cytoplasm, collagen, and muscle fibers. ''E ...

) disease ***

Eosinophilic myocarditis Eosinophilic myocarditis is inflammation in the 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. an eosinoph ...

*** Endomyocardial (tropical) fibrosis *** Löffler's endocarditis ** () Endocardial fibroelastosis ** () Other restrictive cardiomyopathy ** ()

Alcoholic cardiomyopathy Alcoholic cardiomyopathy is a disease in which the chronic long-term abuse of alcohol (i.e., ethanol) leads to heart failure. Alcoholic cardiomyopathy is a type of dilated cardiomyopathy. Due to the direct toxic effects of alcohol on heart muscle ...

** () Other

cardiomyopathies Cardiomyopathy is a group of diseases that affect 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 ...

***

Arrhythmogenic right ventricular dysplasia Arrhythmogenic cardiomyopathy (ACM), arrhythmogenic right ventricular dysplasia (ARVD), or arrhythmogenic right ventricular cardiomyopathy (ARVC), most commonly is an inherited heart disease. ACM is caused by genetic defects of the parts of hea ...

* () Cardiomyopathy 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 Pharmacotherapy is therapy using pharmaceutical drugs, as distinguished from therapy using surgery (surgical therapy), radiation (radiation therapy), movement (physical therapy), or other modes. Among physicians, sometimes the term ''medical ther ...

, physical therapy, bracing for support, surgery, 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