Myopathy

Myopathy refers to a broad range of diseases of skeletal muscle that lead to dysfunction of skeletal muscle. It includes but is not limited to myositis .

Pathology

Etiology

Inflammatory myopathies include infectious myositis as well as idiopathic inflammatory, drug-related, or post-traumatic entities. See the separate article: myositis.

In addition, non-inflammatory myopathies include the following:

• drug-related myopathy
  • steroid myopathy
• hereditary/congenital myopathy, including muscular dystrophy 
  • dystrophinopathies such as Duchenne muscular dystrophy
  • facioscapulohumeral muscular dystrophy
  • inborn errors of metabolism (e.g. glycogen storage disease)
• endocrine myopathy
  • thyroid myopathy (hypothyroidism or hyperthyroidism; including thyroid ophthalmopathy)
  • parathyroid dysfunction (e.g. hyperparathyroidism)
  • adrenal axis dysfunction (e.g. Cushing syndrome)
  • pituitary dysfunction (e.g. acromegaly)
  • diabetic myonecrosis
• denervation myopathy, such as due to peripheral neuropathy

Radiographic features

The imaging findings vary by chronicity . Chronic myopathies appears as fat replacement and atrophy (sarcopenia), sometimes with mineralization or ossification.