Patient with Kearns-Sayre syndrome exhibiting abnormal magnetic resonance image of the brain.

A 33-year-old Japanese man had Kearns-Sayre syndrome (KSS), which consists of the triad of external ophthalmoplegia, heart block, and "salt-and-pepper" retinopathy. The other systemic manifestations included sensorineural hearing loss, slight generalized muscle weakness, cerebellar ataxia, and elevated levels of cerebrospinal fluid protein. He exhibited a heteroplasmic mitochondrial DNA deletion of approximately 9 kb between the cytochrome c oxidase subunit 1 and cytochrome b genes. In the authors' experience, this deletion is one of the longest to be observed in such patients. His fundi were characterized bilaterally by white flecks in the inner layers of retina at the midperiphery. Visual evoked potentials showed delayed latency in the P100 component. The tibial somatosensory evoked potential revealed a marked prolongation of interpeak latency between the N20 and P40 components. Brain magnetic resonance images revealed high-intensity foci in several regions on T2-weighted images. Electrophysiological and magnetic resonance imaging findings suggested an involvement of the white matter of the central nervous system in this patient that was not reflected in the clinical findings.