Myopathy Mitochondrial Symptoms

Mitochondrial myopathies produce a number of symptoms that range from mild to severe. No cure exists within this group of rare neuromuscular diseases. However, many of the specific symptoms of mitochondrial myopathies are widely experienced in the general population. This makes them easier to treat with common medications and procedures along with natural and physical therapies.

Sometimes sufferers who have more general symptoms are also classified as sufferers of “metabolic diseases of the muscle” and fall within the wider umbrella of muscular dystrophy disorders.

Overview of Mitochondrial Myopathy

Mitochondria are present in human cells, existing to produce energy in organs throughout the body. They are particularly important in muscle, brain, heart and nerve tissue. When mitochondrial diseases are present, some or all of the mitochondria malfunction. This can result in a buildup of fuel molecules, one of the leading causes of lactic acidosis. In turn, this produces muscle fatigue, one of the more common symptoms of this group of myopathies.

Myopathy can result from a genetic defect among a multitude of diseases passed from one or both parents. When mitochondrial myopathies are present among family members, symptoms can vary widely based on the nature of the cell formations.

Mitochondrial myopathies show prevalence for attacking muscle tissue, with other symptoms following to lesser degrees:

  • In severe cases, blindness and deafness develop.
  • Many individuals develop droopy eyelids (ptosis) and a reduced ability to move the eyeballs.
  • Seizures are also relatively common.

As the disease progresses, other organs are affected and there is a decrease in coordination skills and overall mobility. The term “mitochondrial encephalomyopathy” indicates greater brain involvement.

General Mitochondrial Symptoms

Mitochondrial myopathies encompass many diseases and syndromes. Some produce very mild symptoms, while others are life threatening and can lead to early death. While these are typically inherited, they can also present themselves in adulthood. Generally, symptoms will be noticeable starting in infancy, gaining in significance before the age of 20.

General symptoms of mitochondrial myopathies range from localized problems to widespread disability.

Muscle weakness is perhaps one of the most common symptoms. Exercise intolerance is also a byproduct of mitochondria damage, meaning that exhaustion is extreme under various forms of activity. This fatigue is sometimes accompanied by headaches and nausea. In some conditions, seizures and mitochondrial myopathies also go hand in hand.

Other commonly reported symptoms are:

  • ataxia (loss of coordination)
  • cataracts
  • diabetes
  • gastrointestinal disorders
  • learning disabilities
  • loss of hearing
  • stunted growth.

These are issues that can also indicate any number of non-related diseases. Experts suggest that if at least three of the above symptoms are present, mitochondrial myopathies will be suspected.

Syndrome Specific Symptoms of Mitochondrial Myopathy

Recognized syndromes within the family of mitochondrial myopathy diseases produce a range of specific and general symptoms. These will vary according to how the defective gene is inherited: whether it’s in the “nuclear” genes or in the genes of the mitochondria. A few disorders in this group are among the most common.

Kearns-Sayre Syndrome (KSS) – Symptoms include PEO (progressive external ophthalmoplegia) and pigmentation of the retinas that can affect vision.

Leigh’s Syndrome – Often evidenced by muscle deterioration and difficulties in speaking and swallowing, this disease may affect eye movements as well. Other symptoms include:

  • ataxia (loss of coordination)
  • brain abnormalities
  • loss of hearing
  • seizures
  • vision impairment.

MDS (Mitochondrial DNA Depletion Syndrome) – Develops in infants and produces a range of symptoms, including:

  • brain abnormalities
  • delays in developmental skills
  • difficulties with feeding
  • liver failure
  • muscle weakness.

MELAS (Mitochondrial Encephalomyopathy, Lactic Acidosis and Stroke-Like Episodes) – This disease becomes more evident in children and adults. Children are generally shorter and can present other mild to severe symptoms that include:

  • diabetes
  • loss of hearing
  • migraines
  • muscle fatigue
  • strokes.

MERRF (Myoclonus Epilepsy with Ragged Red Fibers) – MERRF typically presents in early adolescence and often inhibits growth, along with other symptoms, including:

  • ataxia
  • hearing loss
  • muscle weakness
  • seizures
  • spasmodic muscles.

MNGIE (Mitochondrial Neurogastrointestinal Encephalomyopathy) – This disease can produce PEO and a host of other symptoms, including:

  • chronic diarrhea
  • digestive issues
  • ptosis
  • sensory impairment.

NARP (Neuropathy, Ataxia and Retinitis Pigmentosa) – NARP can occur any time from infancy to adulthood. Common symptoms include:

  • ataxia
  • dementia
  • developmental disabilities
  • retinal degeneration (retinitis pigmentosa).

Pearson Syndrome – This syndrome is generally present in infants with symptoms including anemia and pancreatic malfunction. If a child lives into the teens or beyond, he or she is likely to exhibits signs of KSS.

PEO (Progressive External Ophthalmoplegia) – This condition can be chronic (CPEO) and is usually manageable in its milder forms. It receives a “syndrome” classification, but is also a general symptom of many forms of the disease. PEO is the gradual paralysis of the muscles in the eye area, including ptosis.

Prognosis of Symptoms and Syndromes

Once diagnosed, mitochondrial myopathy symptoms can progress slowly, but this depends on organ involvement and severity of episodic occurrences. Each individual is different and will respond or react to treatments in varying ways. Diet plays a role in some instances, and medications can control such symptoms as diabetes and digestive issues.

It remains difficult to judge longevity and progression, as mitochondrial myopathies can lie dormant before a reoccurrence or move very rapidly. With even more rarity, some subsets, such as dysautonomic mitochondrial myopathy, can lead to early death.

Resources (2006). Facts About Mitochondrial Myopathies. Retrieved January 9, 2008, from the MDA Web site: (2006). Mitochondrial Myopathies. Retrieved January 9, 2008, from the MDA Web site: (1997-2001). Mitochondrial Myopathy. Retrieved January 9, 2008, from the Special Child Web site: