Magnetic Resonance Angiogram Findings of Internal Carotid Artery Narrowing and Anterior Cerebral Artery Hypoplasia Associated With Optic Atrophy After Neonatal Extracorporeal Membrane Oxygenation

Photo and Video Essay Section Editors: Melissa W. Ko, MD Dean M. Cestari, MD Peter Quiros, MD Magnetic Resonance Angiogram Findings of Internal Carotid Artery Narrowing and Anterior Cerebral Artery Hypoplasia Associated With Optic Atrophy After Neonatal Extracorporeal Membrane Oxygenation Alexander E. Pogrebniak, MD, Matthew A. Marcus, MD FIG. 1. MRA showing narrowed right internal carotid artery (ICA) and narrowed A-1 segment of the right anterior cerebral artery (ACA). 3D time of flight magnetic resonance angiogram image of the Circle of Willis demonstrating a narrowed right ICA (short arrow) compared with the left and showing a diffusely narrowed A-1 segment of the right ACA (long arrow). Abstract: We use MRA to elucidate a potential association of unilateral optic atrophy in infancy, ipsilateral internal carotid artery narrowing after extracorporeal membrane oxygenation, and ipsilateral hypoplasia of the A1 segment of the anterior cerebral artery. Journal of Neuro-Ophthalmology 2021;41:e209–211 doi: 10.1097/WNO.0000000000001072 © 2020 by North American Neuro-Ophthalmology Society Department of Ophthalmology (AEP), Prisma Health-University of South Carolina, Columbia, South Carolina; and Pitts Radiology (MM), Columbia, South Carolina. The authors report no conflicts of interest. Address correspondence to Alexander Pogrebniak, MD, Department of Ophthalmology, Prisma Health-University of South Carolina, 9 Medical Park Drive, Suite 340, Columbia, SC 29203; E-mail: [e-mail] Pogrebniak and Marcus: J Neuro-Ophthalmol 2021; 41: e209-e211 W e examined 2 infants initially at age 3 months referred by their pediatricians because of a history of neonatal extracorporeal membrane oxygenation (ECMO) and concern for increased risk of strabismus. Infant 1 was born at 41 weeks gestational age, weighing 3,533 g, after a C-section birth associated with meconium aspiration syndrome and respiratory failure. Within 24 hours, an arteriovenous cannulation of the right neck was performed with initiation of ECMO for 4 days. Infant 2 was born at 40 weeks gestational age, weighing 3,277 g, after a C-section birth associated with meconium aspiration syndrome and severe sepsis leading to respiratory failure. Within 6 hours, an arteriovenous cannulation of the right neck was performed with initiation of ECMO for 10 days. On ophthalmic e209 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo and Video Essay examination at age 3 months and again at 7–8 months, both infants demonstrated poor vision right eye with searching nystagmus when tested monocularly, right exotropia, a right afferent pupil defect, 3+ pallor of the right optic disc without edema, and normal vision and findings in the left eye. Both infants had normal complete blood count, venereal disease research laboratory, and Lyme titer tests. Infant 1 had imaging at age 7 months. MRI of the orbits demonstrated right optic nerve atrophy; MRI of the brain was normal. MRA showed a small caliber right internal carotid artery (ICA; short arrow) compared with the left ICA (Fig. 1). On MRA, there was also narrowing of the A1 segment (long arrow) of the right anterior cerebral artery (ACA), limiting collateral flow around the Circle of Willis from the left side (Fig. 1). The chronic ICA changes are presumably related to ECMO and right-sided cannulation. Infant 2 had imaging at 5 months of age. MRI of the orbits showed right optic nerve atrophy compared with the left (Fig. 2A). MRI of the brain showed mild thinning of the corpus callosum and a punctate area in the right frontal lobe that may indicate a very small prior hemorrhage. MRA showed a stenotic right ICA compared with the left ICA (Fig. 2B), with reduced flow through the right ICA and absence of flow through the right common carotid artery (CCA) (Fig. 2B), implying that all flow to the right ICA is likely originating from within the brain or from small collateral arteries. The MRA also showed narrowing of the A1 segment of the right ACA, reducing collateral flow around the Circle of Willis from the left side (Fig. 2C). The chronic ICA and CCA stenosis are presumably related to ECMO and right-sided cannulation. To our knowledge, there are no published reports describing unilateral optic atrophy in neonates associated with imaging findings of ipsilateral ICA stenosis after ECMO. We believe that the carotid artery stenosis postECMO, in each case ipsilateral to the optic atrophy, along with a variant (likely congenitally hypoplastic) A1 ACA segment, also ipsilateral to the optic atrophy, combined to facilitate ischemic pathology to the optic nerve (we were not able to visualize the ophthalmic arteries directly). Given the young age of these infants, we cannot state whether posterior ischemic optic neuropathy (PION), anterior ischemic neuropathy (AION), or central retinal artery occlusion (CRAO) were most responsible. We favor the possibility of PION. As regards CRAO, we did not see attenuated retinal vessels, funduscopic atrophy of retinal tissue, or macular pigment mottling as could be seen in central retinal artery occlusion. We are unable to perform retinal optical coherence tomography (without anesthesia) because of the patients’ young ages. As regards AION (excluding giant cell arteritis), it is typically related to small-vessel disease in a crowded optic disc rather than carotid artery disease (1). In a small number of adult cases, ischemic optic neuropathy (both posterior and anterior) has been associated with carotid artery pathology, including obstructions (2) and dissections (3). We believe it is notable that both patients present with imaging demonstrating narrowing of the A1 segment of the right ACA compared with the left (ipsilateral to the eye affected by ECMO and optic atrophy). The ophthalmic artery originates as the first branch from the ICA before the start of the A1 segment of the ACA. Narrowing of the A1 segment of the ACA is relatively common, with hypoplasia occurring in approximately 10% of patients (whereas prevalence of ICA hypoplasia is 0.08%) (1). A1 segment stenosis from catheterization is not likely in our cases in the presence of normal PCA and middle cerebral artery. In general, the Circle of Willis can compensate for reduced blood flow coming from unilateral ICA stenosis (4), but patients with narrowed A1 segments are more susceptible to symptomatic carotid artery stenosis (5). In both cases here presented, the vascular effects of ECMO may have been exacerbated by the patients’ hypoplasia of the ipsilateral A1 segment of the ACA. Although reduced blood supply related to respiratory failure and cardiopulmonary instability could have played an additional role in FIG. 2. Imaging demonstrating right optic nerve atrophy, occlusion of the right common carotid artery (CCA), and narrowing of the right internal carotid and anterior cerebral arteries. A. Coronal T2 weighted image demonstrates optic atrophy with a larger volume of cerebrospinal fluid signal surrounding the right optic nerve (arrow). B. Time of flight MRA image of the carotid arterial systems in the neck demonstrates occlusion of the origin of the right CCA (long arrow) with collateral vessel reconstitution of flow more peripherally through the asymmetrical smaller right internal carotid artery (short arrows). C. Time of flight MRA image of the Circle of Willis demonstrates asymmetrically small caliber A1 segment of the right anterior cerebral artery (arrow). e210 Pogrebniak and Marcus: J Neuro-Ophthalmol 2021; 41: e209-e211 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Photo and Video Essay the development of ischemia in these cases, bilateral disease could be expected with those systemic mechanisms alone. Despite the vascular findings, the patients presented did not exhibit signs of cerebral ischemia; this could be explained by the anastomosis and support of the posterior communicating arteries distal to the ophthalmic artery. Unfortunately, there is usually not time for MRA studies to assess for hypoplastic ACA A1 segments before urgent ECMO in neonates. In light of our reported cases, however, we recommend that ophthalmologists consider ordering MRA of the head and neck when evaluating optic atrophy after ECMO, to better elucidate the diagnosis, even if it is not part of the standard workup. STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: A. E. Pogrebniak; b. Acquisition of data: A. E. Pogrebniak and M, Marcus; c. Analysis and interpretation of data: A. E. Pogrebniak and M. Marcus. Category 2: a. Drafting the manuscript: A. E. Pogrebniak; b. Revising it for Pogrebniak and Marcus: J Neuro-Ophthalmol 2021; 41: e209-e211 intellectual content: A. E. Pogrebniak and Matthew Marcus. Category 3: a. Final approval of the completed manuscript: A. E. Pogrebniak and Matthew Marcus. REFERENCES 1. Makowicz G, Poniatowska R, Lusawa M. Variants of cerebral arteries—anterior circulation. 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