Progressive external ophthalmoplegia (PEO) is a muscle disorder that affects the eye muscles and progresses slowly. This disease causes drooping of the eyelids (ptosis) and restricts eye movements. PEO generally results from mutations in mitochondrial DNA and can sometimes affect other muscles. Its progressive nature means it worsens over time, and the term “external” indicates that it is limited to the eye muscles.
What Causes Progressive External Ophthalmoplegia?
The primary cause of progressive external ophthalmoplegia is genetic mutations. Specifically, mutations in mitochondrial DNA play a significant role in the onset of this disease. The main genetic causes leading to PEO include:
Mitochondrial DNA Mutations: Mutations in mitochondrial DNA cause mitochondrial dysfunctions.
Nuclear DNA Mutations: In some cases, mutations in nuclear DNA can also lead to PEO. For instance, mutations in the POLG, TWNK, and RRM2B genes can trigger the disease.
Autosomal Dominant or Recessive Inheritance: PEO can be inherited through both autosomal dominant and autosomal recessive inheritance. In autosomal dominant inheritance, a mutation from only one parent is sufficient for the disease to manifest.
What Are the Symptoms of Progressive External Ophthalmoplegia?
The symptoms of progressive external ophthalmoplegia include:
- drooping eyelids
- restricted eye movements
- double vision
- muscle weakness
- exercise intolerance
- respiratory problems
- heart rhythm disorders
- difficulty swallowing
How Is Progressive External Ophthalmoplegia Diagnosed?
The diagnosis of PEO usually relies on clinical symptoms and a detailed patient history. Various tests and methods are used to confirm the diagnosis:
Physical Examination: Observations of drooping eyelids and restricted eye movements.
Family History: Inquiry into whether other family members have similar symptoms.
Genetic Tests: Genetic tests to detect mutations in mitochondrial and nuclear DNA.
Muscle Biopsy: Examination of muscle tissue samples under a microscope to identify mitochondrial disorders.
Blood Tests: Measurement of biochemical markers indicating muscle damage, such as creatine kinase (CK) levels.
Imaging Tests: MRI or CT scans to evaluate abnormalities in muscle and nerve structure.
How Is Progressive External Ophthalmoplegia Treated?
There is no definitive cure for PEO, but various treatment methods can manage symptoms and slow the disease’s progression:
Surgical Intervention: Surgical procedures on the eyelids to correct ptosis.
Glasses and Prism Lenses: Special glasses and prism lenses to correct double vision and improve visual quality.
Physical Therapy: Exercise programs to enhance muscle strength and mobility.
Pharmacological Treatments: Vitamin and coenzyme supplements to support mitochondrial function.
Cardiac and Respiratory Support: Appropriate treatments and devices for heart rhythm disorders and respiratory problems.
How Should Progressive External Ophthalmoplegia Be Managed?
Managing PEO focuses on controlling symptoms and improving patients’ quality of life. Management strategies include:
Regular Follow-Up: Regular check-ups by neurologists and ophthalmologists.
Nutrition and Diet: A balanced and nutritious diet to support mitochondrial health.
Psychological Support: Psychological counseling and support groups to cope with the disease.
Exercise Programs: Regular exercises to enhance muscle strength and flexibility.
Family Education: Educating family members on disease management and daily care.
Monitoring Respiratory and Cardiac Health: Regular monitoring and intervention of respiratory and cardiac functions if necessary.