General description

Chronic progressive external ophthalmoplegia (CPEO) is a mitochondrial disease primarily affecting the external ocular muscles. CPEO is characterized by ptosis and ophthalmoplegia, often accompanied by other skeletal muscle symptoms such as muscle weakness and atrophy, as well as central nervous system involvement, including retinal pigmentary degeneration, hearing loss, and endocrine disorders. Cardiac conduction defects and renal issues like Bartter and Fanconi syndromes are also commonly seen.

Kearns-Sayre syndrome (KSS) is considered a severe form of CPEO and is diagnosed based on the presence of external ophthalmoplegia, retinal pigmentary degeneration, and the onset of neurological or muscular symptoms before age 20. KSS involves multiple organs, with symptoms including mental retardation, short stature, diabetes, hirsutism, and peripheral neuropathy. While both conditions share similar imaging findings, KSS presents more extensive systemic involvement compared to CPEO. KSS typically begins with ptosis and ophthalmoplegia, and while early development is usually normal, the disease progresses to affect multiple systems.