Muscle death

**Muscle death** or **myopathy**, a form of necrosis, is the result of a lack of blood to a muscle resulting in the muscle eventually ceasing to become a living cell. As dead tissue, the muscle then starts to rot, causing gangrene, poisoning the bloodstream and eventually resulting in the death of the patient unless the dead muscle is removed. Several things can cause muscle death, such as a lack of blood due to an infarction or a severe infection such as Necrotizing fasciitis. It is most commmonly seen in severe frostbites.

If the underlying cause is treated before too much muscle dies, the body will be able to process the dead tissue through the liver. However, if it becomes too widespread, amputation is the only sure method of preventing the death of the patient. Otherwise, the dead muscle tissue will overwhelm the body's other organs, particularly the liver.

Fortunately, muscle death is very rare, but its symptoms are not unique to the condition. As a result, it is difficult to diagnose.

Gregory House suffered from muscle death after his infarction. Instead of agreeing to amputation, he attempted to treat the condition by having the arteries that fed the muscle bypass it, restoring circulation to still living tissue while slowing the entry of dead tissue into the blood stream, hoping that the muscle would heal and allow him the use of most of his leg. However, the procedure was very painful during the recovery period and he agreed to be put into an induced coma. During his coma, his medical proxy, his girlfriend Stacy, instead had the dead muscle removed entirely.

The delay in diagnosis and the removal of the muscle both weakened House's right leg and left him with chronic pain. It also cost him his relationship with Stacy.

In medicine, **myopathy** is a disease of the muscle in which the muscle fibers do not function properly. This results in muscular weakness. *Myopathy* means muscle disease (Greek : myo- *muscle* + patheia : *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.

## 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. 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.

### Inherited forms

* 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.
* Myotonia
	+ Neuromyotonia
* 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:
	+ Nemaline myopathy (characterized by presence of "nemaline rods" in the muscle),
	+ Multi/minicore myopathy (characterized by multiple small "cores" or areas of disruption in the muscle fibers),
	+ Centronuclear myopathy (including myotubular myopathy) (in which the nuclei are abnormally found in the center of the muscle fibers), a rare muscle wasting disorder
* Mitochondrial myopathies, which are due to defects in mitochondria, which provide a critical source of energy for muscle
* Familial periodic paralysis
* Inflammatory myopathy, which are caused by problems with the immune system attacking components of the muscle, leading to signs of inflammation in the muscle
* Metabolic myopathy, which result from defects in biochemical metabolism that primarily affect muscle
	+ Glycogen storage diseases, which may affect muscle
	+ Lipid storage disorder
* Other myopathies
	+ Brody myopathy
	+ Congenital myopathy with abnormal subcellular organelles
	+ Fingerprint myopathy
	+ Inclusion body myopathy 2
	+ Megaconial myopathy
	+ Myofibrillar myopathy
	+ Rimmed vacuolar myopathy

### Acquired

* External substance induced myopathy
	+ 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 - including atypical myopathy in horses caused by toxins in Sycamore seeds and seedlings.
* (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.
	+ Polymyositis 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.
* Myositis ossificans
* Rhabdomyolysis and 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.

* Statin-associated autoimmune myopathy

### Myocardium / cardio-myopathy

* Acute myocarditis
* Myocarditis in diseases classified elsewhere
* Cardiomyopathy
	+ Dilated cardiomyopathy
	+ Obstructive hypertrophy cardiomyopathy
	+ Other hypertrophic cardiomyopathy
	+ Endomyocardial (eosinophilic) disease
		- Eosinophilic myocarditis
		- Endomyocardial (tropical) fibrosis
		- Löffler's endocarditis
	+ Endocardial fibroelastosis
	+ Other restrictive cardiomyopathy
	+ Alcoholic cardiomyopathy
	+ Other cardiomyopathies
		- Arrhythmogenic right ventricular dysplasia
* 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, physical therapy, bracing for support, surgery, and massage are all current treatments for a variety of myopathies.Template:Cn

## External links

* GeneReviews/NCBI/NIH/UW entry on Myopathy with Deficiency of ISCU
* See http://neuromuscular.wustl.edu/ for medical descriptions.
* Myopathy at Wikipedia

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