Patients with Kearns-Sayre syndrome have
1. External opthalmoplegia
2. Ptosis
3. Retinitis pigmenti
4. One of the following before the age of 20 years
i. Complete heart block
ii. CSF protein > 100 mg/dL
iii. Cerebellar ataxia
On imaging patients have similar features to Progressive external opthalmoplegia with calcification of the deep cerebral and cerebellar nuclei. Patients have increased T2 signal in the dorsal midbrain, medial and posterior thalami, and the globi pallidi. Patients have increased T2 signal in the subcortical U fibres with preservation of the periventricular white matter signal. Affected white matter shows restricted diffusion. MRS shows increased lactate and reduced NAA.