Painless, Pupil-Sparing but Otherwise Complete Oculomotor Nerve Paresis Caused by Basilar Artery Aneurysm

To the Editor. —Oculomotor nerve paresis is a well-known sign of enlargement or rupture of an intracranial aneurysm. The aneurysm is usually located at the junction of the posterior communicating and internal carotid arteries, but occasionally may be at the tip of the basilar artery. The oculomotor nerve paresis may be complete or incomplete, but it is usually characterized by damage to pupillomotor fibers, resulting in an enlarged, poorly reactive pupil on the side of the paresis. In addition, oculomotor nerve paresis caused by an intracranial aneurysm is almost always associated with severe ocular or periorbital pain. We describe a patient in whom an intracranial aneurysm that originated at the tip of the basilar artery produced a painless, pupil-sparing, but otherwise complete oculomotor nerve paresis. Report of a Case. —A 65-year-old, hypertensive woman presented to the Wilmer Institute of The Johns Hopkins Hospital, Baltimore, with a one-month history of complete