Intracranial internal carotid artery aneurysm as a cause of Raeder's paratrigeminal syndrome.

A 26-year-old woman was first seen with severe facial pain, partial Horner's syndrome, and restriction of ocular movements on the right side--all features of Raeder's paratrigeminal syndrome. Right carotid angiogram revealed an aneurysm of the internal carotid artery. This is the second reported case of Raeder's syndrome due to an aneurysm of the intracranial portion of the internal carotid artery. The mechanism of facial pain and sympathetic involvement are discussed.