Ischemic optic neuropathy associated with internal carotid artery dissection

Background: Ischemic optic neuropathy (ION) is an infarction of the anterior or, less frequently, posterior part of the optic nerve, usually due to a disease of small arteries supplying the optic nerve. Carotid stenosis or occlusions are rare causes, and among them, carotid dissections have been so far reported in only 5 cases. Methods: We describe 4 patients with ION (2 anterior and 2 posterior) due to internal carotid artery dissection of a consecutive series of 110 patients with internal carotid artery dissection (3.6%). Results: None of the patients had signs of central retinal artery occlusion or ischemic ocular syndrome. Ischemic optic neuropathy occurred after a mean of 5.3 days (range, 3-8 days) following the first symptom, which was headache in 1 patient, transient monocular blindness in 2, and hemispheric transient ischemic attack in 1. One patient had associated Horner syndrome, and 2 had severe ipsilateral headache and orbital pain. None of the patients developed a cerebral infarction. These features differ from those observed in "classic" nonarteritic anterior ION and might therefore point to carotid dissection. Conclusion: Ischemic optic neuropathy may occur as an early sign of carotid dissection: young age, previous transient monocular blindness, an association with pain, Horner syndrome, or hemispheric transient ischemic attacks are suggestive of this cause and should prompt confirmatory investigations.