Ptosis as the sole manifestation of compression of the oculomotor nerve by an aneurysm of the posterior communicating artery.

Oculomotor palsy secondary to a berry aneurysm is usually present with pupillary dilatation, followed by other signs of third cranial nerve dysfunction, including oculomotor paresis and ptosis. Partial paralysis of the nerve with pupil sparing has been observed, but ptosis as the sole sign of oculomotor paralysis has not previously been reported until now.