Clinical Reasoning: Acute Monocular Vision Loss in a Patient With Ipsilateral Extracranial Chronic Internal Carotid Artery Occlusion

Abstract

We report the case of a middle-aged man who presented with acute painless monocular vision loss. His medical history was remarkable for chronic total occlusion of the ipsilateral internal carotid artery (ICA) and a recent carotid endarterectomy (CEA) on the contralateral ICA. In a stepwise multidisciplinary approach assessment, we review the differential diagnosis of acute vision loss and investigate how the patient's intracranial and extracranial hemodynamic reorganization after chronic ICA occlusion may affect the clinical reasoning. Early complications of CEA and the differential diagnosis of new-onset anisocoria are also discussed.

Figure 1. Intracranial and Extracranial Circulation in the Lateral View

The illustration highlights the potential vascular routes that the external carotid artery thrombus may have traversed to reach our patient's ophthalmic artery (colored in dark red). The occluded extracranial internal carotid artery is colored grey. 1: common carotid artery; 2: external carotid artery; 3: facial artery; 4: internal maxillary artery; 5: ophthalmic artery; 6: middle meningeal artery; 7: leptomeningeal collaterals; 8: internal carotid artery; 9: anterior cerebral artery; 10: middle cerebral artery; 11: basilar artery; 12: posterior cerebral artery; 13: occipital artery; and 14: vertebral artery.

Figure 2. CT Angiography and Intraoperative Images

Sagittal (A) and axial (B) CT angiography revealed an intraluminal thrombus at the origin of the ECA (yellow arrows), whereas the extracranial ICA is completely occluded (white arrows). Cerebral blood flow in the supraclinoid segment of the right internal carotid artery and its terminal branches is provided by collateral circulation (yellow asterisks), namely the ophthalmic artery (C), the anterior communicating artery, and the posterior communicating artery (D). A surgical incision at the internal carotid bulb revealed a lipid plaque resulting in complete occlusion of ICA (white arrow) and partial occlusion of ECA (yellow arrow) and CCA (E). An endarterectomy was performed, then the arteries were repaired with a Dacron patch, excluding the nonfunctional ICA (F). CCA = common carotid artery; ECA = external carotid artery; ICA = internal carotid artery.