Background: Isolated superior rectus palsy due to a contralateral midbrain lesion has not been reported.
Case description: A 71-year-old woman suddenly developed diplopia. Examination showed that she had isolated superior rectus paresis. Magnetic resonance imaging showed a tiny infarct at the area of the oculomotor nucleus on the contralateral side.
Conclusion: Isolated superior rectus palsy may be caused by a contralateral midbrain lesion that selectively involves crossing superior rectus nerve fibers.