Progressive external ophthalmoplegia
Chronic progressive external ophthalmoplegia (CPEO) is a rare mitochondrial ocular disorder.
Clinical presentation
Patients present with slowly progressive bilateral ophthalmoplegia (limitation of eye motion) and blepharoptosis.
The entity can manifest in isolation or as a syndrome with other neurological deficits, the latter of which is referred to as CPEO+. One specific syndromic variant of CPEO is Kearns-Sayre syndrome, which additionally has a pigmentary retinopathy and cardiac conduction abnormalities.
Pathology
Genetics
Patients either have a large deletion of mitochondrial DNA or multiple deletions due to mutations in nuclear genes that affect mitochondrial DNA repair or replication .
Radiographic features
MRI
Patients show variable levels of mild to moderate extraocular muscle atrophy (25-60% volume loss compared to normal controls) . The findings should be bilaterally symmetric.
Some affected patients show extraocular muscle signal abnormalities, including T1 hyperintensity and very occasionally STIR hyperintensity . The T1 hyperintensity appears spongiform or like streaks within the muscle .