3. Symptoms and Signs:

Symptoms include weakness, fatigue and pain in muscles due to lactic acidosis. There usually are associated extramuscular problems, such as mitochondrial encephalopathy and stroke like syndrome. These extramuscular disorders can manifest as dementia, stroke, transient ischemic attack, myoclonic epilepsy, ophthalmoplegia and cardiac conduction defects.

4. Muscle Biopsy:

Muscle biopsy reveals ragged red muscle fibers with glycogen and lipid deposits. It also shows increased activity of succinate dehydrogenase and reduced activity of cytochrome c oxidase.

5. Treatment:

There is no specific treatment for mitochondrial myopathy however physiotherapy reduces disability and improves functionality.

6. Prognosis:

Prognosis depends on type of mitochondrial disorder and extent of involvement of extramuscular sites. It ranges from significant disability to death.