Chronic Progressive External Ophthalmoplegia (CPEO) – is a condition characterized by a loss of the muscle functions involved in eye and eyelid movement. Signs and symptoms tend to begin between the ages of 18 and 40 and commonly include weakness or paralysis of the muscles that move the eye (ophthalmoplegia) and drooping of the eyelids (ptosis).
Sometimes, CPEO may be associated with other signs and symptoms. Some affected individuals also have general weakness of the skeletal muscles (myopathy), which may be especially noticeable during exercise. Muscle weakness may also cause difficulty swallowing. In these cases, the condition is referred to as “progressive external ophthalmoplegia plus” (PEO+). Additional signs and symptoms can include hearing loss caused by nerve damage in the inner ear (sensorineural hearing loss), weakness and loss of sensation in the limbs due to nerve damage (neuropathy), impaired muscle coordination (ataxia), a pattern of movement abnormalities known as parkinsonism, or depression.
CPEO can be caused by mutations in any of several genes, which may be located in mitochondrial DNA or nuclear DNA. It has different inheritance patterns depending on the gene involved in the affected individual.
Treatment of ptosis includes surgical correction, or using glasses that have a “ptosis crutch” to lift the upper eyelids. Strabismus surgery can be helpful in carefully selected patients if diplopia (double vision) occurs. Some individuals with a deficiency of coenzyme Q10 have CPEO as an associated abnormality. Coenzyme Q10 is important for normal mitochondrial function. In individuals with this deficiency, supplemental coenzyme Q10 has been found to improve general neurologic function and exercise tolerance. However, coenzyme Q10 has not been shown to improve the ophthalmoplegia or ptosis in people who have isolated CPEO.