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 subacutely. On the other hand,
familial myopathies or
dystrophies generally present in a
chronic fashion with exceptions of
metabolic myopathies, in which 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 • (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 and eventually death, usually related to
respiratory 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 (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 • (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 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. (M33.2) •
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. • (M60.9)
Benign acute childhood myositis • (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. •
Statin-associated autoimmune myopathy ===
Myocardium /
cardiomyopathy=== • ()
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==