Ten consecutive patients with acute relative pupillary sparing third n
erve palsies were enrolled in a prospective study to determine the pre
valence of intracranial aneurysm. All patients were imaged with either
cerebral angiography or magnetic resonance angiography. None of the p
atients demonstrated an intracranial aneurysm. The prevalence of aneur
ysm in patients with relative pupillary sparing third nerve palsies ma
y be low enough to preclude the use of routine angiography in this con
dition.