Mitochondrial myopathy

Mitochondrial myopathy
Classification and external resources
Simplified structure of a typical mitochondrion
ICD-10	G71.3
MeSH	D017240

Mitochondrial myopathy is a type of myopathy associated with mitochondrial disease. On biopsy, the muscle tissue of patients with this disease usually demonstrate "ragged red" muscle fibers. These ragged-red fibers contain mild accumulations of glycogen and neutral lipids, and may show an increased reactivity for succinate dehydrogenase and a decreased reactivity for cytochrome c oxidase. Inheritance is maternal (non-Mendelian extranuclear). There are several subcategories of mitochondrial myopathies.

Treatment

Although no cure currently exists, there is hope in treatment for this class of hereditary diseases with the use of an embryotic mitochondrial transplant.

Signs and symptoms

Signs and symptoms include:

• Mitochondrial encephalomyopathy, lactic acidosis, and stroke-like syndrome (MELAS)
  • Varying degrees of cognitive impairment and dementia
  • Lactic acidosis
  • Strokes
  • Transient ischemic attacks
  • Hearing loss
  • Weight loss

• Myoclonic epilepsy and ragged-red fibers (MERRF)
  • Progressive myoclonic epilepsy
  • Clumps of diseased mitochondria accumulate in muscle fibers and appear as "ragged-red fibers" when muscle is stained with modified Gömöri trichrome stain
  • Short stature

• Kearns-Sayre syndrome (KSS)
  • External ophthalmoplegia
  • Cardiac conduction defects
  • Sensorineural hearing loss

• Chronic progressive external ophthalmoplegia (CPEO)
  • Progressive ophthalmoparesis
  • Symptomatic overlap with other mitochondrial myopathies