, a myopathy
is a neuromuscular disease
in which the muscle fibers
do not function for any one of many reasons, resulting in muscular weakness
. "Myopathy" simply means muscle disease (myo- Greek
μυσ "muscle" + -pathy Greek
"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 etc.). Muscle cramps
, and spasm
can also be associated with myopathy.
Because myopathy is such a general term, there are several classes of myopathy.... (ICD-10
codes are provided where available.)
- (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.
- Examples include duchenne muscular dystrophy, an x-linked condition affecting the dystrophin gene (Xp 21). Duchenne muscular dystrophy is characterised by promixal muscle weakness, seen most commonly by difficulty walking, using gower's manouvre to stand, and hypertrophy of the calf muscles. It is typically found around the age of 4, and sufferers are wheelchair bound by the age of 10. It severely limits lifespan, as most patients die in their early twenties of respiratory complications.
- other congential muscular dystrophies include - Limb-girdle dystrophy, myotonic dystrophy, fascio-scapular-humeral dystrophy, and distal.
- (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. Among others, different congenital myopathies include:
- (G71.3) Mitochondrial myopathies are due to defects in mitochondria, which provide a critical source of energy for muscle.
- (G72.3) Familial periodic paralysis
- (G72.4) Inflammatory myopathies 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 result from defects in biochemical metabolism that primarily affect muscle
- Dermatomyositisis the same as polymyositis, but also shows skin changes - a violaceous periorbital rash, facial erythema, blue or red patches on the knuckles, ragged nail folds and dilated nail capilliaries. (M33.2)
- polymyositis which has tender, weak muscles, a mild normocytic anaemia, raised creatinine kinase and inflammatory markers and shows short polyphasic action potentials on EMG. it is treated by immunosupressants like corticosteroids or azathioprine.
- inclusion body myositis, and related myopathies
- (M61) Myositis ossificans
- (M62.89) Rhabdomyolysis and (R82.1) myoglobinurias
- Common muscle (R25.2) cramps and (M25.6) stiffness, and (R29.0) tetany
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 even acupuncture
are current treatments for a variety of myopathies.