Mitochondrial Myopathies (MM)

Medical Management

While mitochondrial myopathies and encephalomyopathies are relatively rare, some of their potential complications, such as heart problems, stroke, seizures, migraines, deafness and diabetes, are common in the general population, and have well-established, effective treatments.

These complications are often the most serious aspects of mitochondrial disease, and many can be successfully managed with medications, dietary adjustments, and lifestyle changes. With regular monitoring and health check-ups, people living with mitochondrial diseases can help prevent or minimize life-threatening problems.

Coordinated care

Care for mitochondrial disease is often multidisciplinary. Neurology, cardiology, pulmonology, endocrinology, gastroenterology, ophthalmology, audiology, genetics, and therapy services may all play a role. Many clinics use a care summary or emergency letter to communicate key medical information across providers.

Common areas of management

Interventional Therapies
Until recently, treatment options for mitochondrial myopathies have been limited to supportive care, but advances are being made, particularly for specific conditions like Thymidine Kinase 2 Deficiency (TK2d).

In 2025, the U.S. Food and Drug Administration (FDA) approved the combination of doxecitine and doxribtimine (brand name KYGEVVI®) as the first and only treatment for TK2d in adults and children whose symptoms began on or before 12 years of age. This therapy replaces the missing mitochondrial DNA building blocks, deoxycytidine and deoxythymidine, helping restore mitochondrial function and slow or stabilize disease progression. Clinical data showed that KYGEVVI® reduced the risk of death by about 86% compared with untreated patients. The most common side effects included diarrhea, vomiting, elevated liver enzymes, and abdominal pain. This therapy represents an important development in the treatment of TK2d and highlights ongoing progress toward targeted therapies for mitochondrial disease.

Ataxia and mobility issues

Often, mitochondrial encephalomyopathy causes ataxia, or trouble with balance and coordination. People with ataxia are usually prone to falls. Sometimes, people with mitochondrial myopathies experience loss of muscle strength in the arms or legs. These problems can be partially avoided through physical and occupational therapy, and the use of supportive aids such as railings, a walker, a cane, braces, or — in severe cases — a wheelchair.

Breathing issues

Sometimes, mitochondrial diseases can cause weakness in the breathing muscles or brain abnormalities that alter the brain's control over breathing. Those with mild respiratory problems might require occasional respiratory support, such as pressurized air, while someone with more severe problems might require permanent support from a ventilator. Those with mitochondrial disorders should watch for signs of respiratory insufficiency (such as shortness of breath or morning headaches), and have their breathing checked regularly by a specialist.

Cardiac care

Mitochondrial disease can affect the heart, often by causing an interruption in the heartbeat called a conduction block or other cardiac arrythmia. Although dangerous, this condition is treatable with a pacemaker, which stimulates normal beating of the heart. Cardiac muscle damage also may occur such as thickening or dilation of the heart called cardiomyopathy. People with mitochondrial disorders may need to have regular examinations by a cardiologist or electrophysiologist (EP specialist).

Developmental delays

Children with mitochondrial diseases may have delays in reaching motor milestones such as sitting, crawling and walking. As they get older, they may have trouble moving around, speech problems, and/or learning disabilities. Children who are severely affected by these problems may benefit from services such as physical therapy, speech therapy and possibly an individualized education program (IEP) at school.

Dietary supplements

Some clinicians use supplements such as Coenzyme Q10 (CoQ10), L-carnitine (when levels are low), or certain vitamins. Evidence varies, and the decision to use supplements is individualized. Consensus guidelines do not recommend a universal “mitochondrial cocktail,” but rather an approach tailored to each person’s situation.

Headaches and seizures

Often, headaches can be alleviated with medications, and seizures can be prevented with drugs used for epilepsy (anti-epileptics).

Speech and swallowing issues

Mitochondrial myopathies can cause weakness and atrophy (shrinking) of the muscles of the face and neck, which can lead to slurred speech and difficulty swallowing. In these instances, speech therapy or changing the diet to easy-to-swallow foods can be useful. In some cases, a feeding tube may be required to prevent aspiration.

Vision and hearing issues

Although progressive external ophthalmoplegia (PEO) — gradual paralysis of the eye muscles — is a common feature of mitochondrial myopathies, people automatically compensate for PEO by moving their heads to look in different directions and might not even notice any visual problems.

Ptosis (droopy eyelids) is potentially more frustrating because it can impair vision and also cause a listless expression, but it can be corrected by surgery, or by using glasses that have a “ptosis crutch” to lift the upper eyelids.

PEO or ptosis can sometimes cause damage to the developing brain's visual system, so it’s important for children with signs of PEO or ptosis to have their vision checked by a specialist.

Hearing impairment can be managed using hearing aids or cochlear implants and alternate forms of communication.

Additional reading

• Mancuso M et al; 280th ENMC workshop study group. 280th ENMC International Workshop: The ERN EURO-NMD mitochondrial diseases working group; diagnostic criteria and outcome measures in primary mitochondrial myopathies. Hoofddorp, the Netherlands, 22-24 November 2024. Neuromuscul Disord. 2025 May;50:105340. doi: 10.1016/j.nmd.2025.105340.
• Parikh, S. et al. Diagnosis and management of mitochondrial disease: A consensus statement from the Mitochondrial Medicine Society. Genetics in Medicine (2015). doi:10.1038/gim.2014.177

Last reviewed May 2026.