Mitochondrial Myopathies

Mitochondrial myopathies are a group of neuromuscular diseases. Some of the more common mitochondrial myopathies include:

  • Kearns-Sayre syndrome.

  • Myoclonus epilepsy with ragged-red fibers (MERRF).

  • Mitochondrial encephalomyopathy lactic acidosis.

  • Stroke-like episodes (MELAS).


These diseases are caused by damage to the mitochondria. Those are small, energy-producing structures found in every cell in the body. They serve as the cells' "power plants." Nerve cells in the brain and muscles require a great deal of energy. They appear to be particularly damaged when mitochondrial dysfunction happens.


The symptoms include:

  • Muscle weakness or exercise intolerance.

  • Heart failure or rhythm disturbances.

  • Dementia.

  • Movement disorders.

  • Stroke-like episodes.

  • Deafness.

  • Blindness.

  • Droopy eyelids.

  • Reduced ability of the eyes to move.

  • Vomiting.

  • Shaking and twitching (seizures).

The disorders range in severity from progressive weakness to death. The age of onset ranges from birth to adulthood. Most cases occur before the age of 20. Exercise intolerance or muscle weakness usually develops by the age of 20. During physical activity, muscles may become easily fatigued or weak. Muscle cramping may rarely occur. Other symptoms may include:

  • Nausea.

  • Headache.

  • Being out of breath.


There is no specific treatment for any of the mitochondrial myopathies. But physical therapy may extend the range of movement of muscles and improve dexterity. Vitamin therapies may improve function in some patients. They include:

  • Riboflavin.

  • Coenzyme Q.

  • Vitamins C and K.

  • Carnitine. This is a specialized amino acid.