Terms used in this evidence summary

Advice

Chronic progressive external ophthalmoplegia syndromes (CPEO)

Chronic progressive external ophthalmoplegia is a condition characterised mainly by a loss of the muscle functions involved in eye and eyelid movement. Signs and symptoms tend to begin in early adulthood and most commonly include weakness or paralysis of the muscles that move the eye (ophthalmoplegia) and drooping of the eyelids (ptosis). Some people also have general weakness of the skeletal muscles (myopathy), which may be especially noticeable during exercise. Muscle weakness may also cause difficulty swallowing (dysphagia).

Kearns-Sayre syndrome (KSS)

Kearns-Sayre syndrome is a condition that affects many parts of the body, especially the eyes. The features of Kearns-Sayre syndrome usually appear before the age of 20, and the condition is diagnosed by a few characteristic signs and symptoms. People with Kearns-Sayre syndrome have progressive external ophthalmoplegia and pigmented retinopathy. In addition, there is at least one of the following signs or symptoms: cardiac conduction defects, ataxia, or abnormally high levels of protein in the cerebrospinal fluid. People with Kearns-Sayre syndrome may also have muscle weakness, deafness, kidney problems or cognitive function decline.

Medical Research Council muscle scale

The Medical Research Council muscle scale grades muscle power on a scale of 0 to 5 in relation to the maximum expected for that muscle. The studies in the evidence summary presented results for this outcome as a percentage. It is unclear from the information provided in the papers what the percentages represent.

Mitochondrial encephalomyopathy with lactic acidosis and stroke-like episodes (MELAS)

MELAS is one well known clinical manifestation of mitochondrial disease. People with MELAS usually have the following clinical features: stroke-like episodes, encephalopathy with seizures or dementia, mitochondrial myopathy and recurrent headache.

Myoclonic epilepsy with ragged-red fibres (MERRF)

The clinical features that people with MERRF syndrome develop are mainly characterised by generalised seizures, myoclonus, ataxia and muscle weakness.