Kearns-Sayre syndrome with restricted diffusion in subcortical white matter and extraocular muscle atrophy.

Kearns-Sayre Syndrome (KSS) is a rare multisystem mitochondrial disorder affecting muscles, the central nervous system, and the endocrine system. KSS is characterized by T2WI/FLAIR hyperintensities in the subcortical white matter, brainstem, globi pallidi, thalami, and middle cerebellar peduncles. Here, we report a case of KSS with extraocular muscle atrophy in which MRI performed approximately 10 years after the initial MRI examination revealed lesion expansion and diffusion restriction of subcortical white matter affecting U-fibers.