Anterior Ischemic Optic Neuropathy Secondary to Carotid Artery Dissection

A 54-year-old Caucasian male smoker (80 pack-years) with a history of Crohn disease, presented for emergent evaluation of visual loss associated with 10/10 shooting, pulsatile pain radiating vertically through the paramedian right frontoparietal area.

Clinical Correspondence Section Editors: Robert Avery, DO Karl C. Golnik, MD Caroline Froment, MD, PhD An-Guor Wang, MD Anterior Ischemic Optic Neuropathy Secondary to Carotid Artery Dissection Ines Lains, MD, PhD, Jose D. Diaz, MD, John W. Gittinger Jr, MD, Eric D. Gaier, MD, PhD A 54-year-old Caucasian male smoker (80 pack-years) with a history of Crohn disease, presented for emergent evaluation of visual loss associated with 10/10 shooting, pulsatile pain radiating vertically through the paramedian right frontoparietal area. Four days before presentation, he developed a right-sided temporal headache and sudden vision loss to “complete blackness” while watching television. His vision improved partially thereafter. An outside hospital interpreted his computed tomography angiography (CTA) imaging as showing complete occlusion of the right internal carotid artery (ICA). Brain MRI showed multiple foci of acute/subacute ischemia involving the right basal ganglia and subcortical white matter. The patient was discharged on daily aspirin 81 mg. Further subjective decline in vision and increasing pain prompted his emergent presentation for neuroophthalmic evaluation. The visual acuity was count fingers at 69 in the right eye and 20/20 in the left eye. A prominent relative afferent pupillary defect was present on the right without anisocoria. Extraocular motility, intraocular pressure, and anterior segment examinations were unremarkable. Funduscopy revealed pallid edema of the right optic disc and a crowded, but unaffected, left optic disc (Fig. 1A, B). A review of the CTA images revealed tapering of the angiographic signal in the right ICA, consistent with dissection (Fig. 1C–E). The patient was started on continuous intravenous heparin, transitioned to enoxaparin, and then to warfarin. Atorvastatin and a smoking cessation program were initiated. Department of Ophthalmology (IL, JDD, JWG, EDG), Harvard Medical School, Boston, Massachusetts; Department of Ophthalmology (IL, JDD, JWG, EDG), Boston Children’s Hospital, Massachusetts Eye and Ear, Boston, Massachusetts; Department of Ophthalmology, Bascom Palmer Eye Institute (JDD), University of Miami Health System, Miami, Florida; Department of Ophthalmology (EDG), Boston Children’s Hospital, Boston, Massachusetts; and Department of Brain and Cognitive Sciences (EDG), Picower Institute for Learning and Memory, Massachusetts Institute of Technology, Cambridge, Massachusetts. E. D. Gaier reports NIH funding (K08 EY030164). The authors report no conflicts of interest. Address correspondence to Eric D. Gaier, MD, PhD, Department of Ophthalmology, Boston Children’s Hospital, 300 Longwood Avenue, Boston, MA 02115; E-mail: [e-mail] Lains et al: J Neuro-Ophthalmol 2021; 41: e731-e733 At 1-month follow-up, the visual acuity had improved to 20/30 in the right eye, and the optic disc edema had resolved yielding pallor (Fig. 2A, B). Between 1 and 18 months follow-up, his visual field remained severely constricted in the right eye and normal in the left (Fig. 2C, D). Internal carotid artery dissection (ICAD) is a common cause of ischemic stroke in young adults (1), but the spectrum of ophthalmologic manifestations of ICAD is often underappreciated (2). Painful anterior ischemic optic neuropathy (AION) without clinical evidence of Horner syndrome was the presenting sign of ICAD in this case. Few cases of AION secondary to ICAD have been reported, with an estimated prevalence of 1.8% among patients with ICAD (2,3). Early recognition of ICAD is imperative. Although evidence to support immediate antithrombotic treatment is lacking, this approach is routine given the high risk of recurrent stroke (4). This entity may go unrecognized as neuroimaging is typically not performed in the setting of AION (5). The presence and character of the pain was an important clue of this rare cause of AION, and the intense, radiating nature was notably distinct from the dull ache exacerbated by eye movement that is characteristic of inflammatory optic neuropathy (6). Transient monocular blindness followed by improvement is also atypical for nonarteritic AION, but has been described in other cases of AION secondary to ICAD (5), and likely reflects relatively severe ischemia signified by pallid edema. Pallid edema (Fig. 1A) is also a feature distinct from nonarteritic AION, akin to that seen in arteritic AION and hemodialysis-associated AION (6). The presence of a “disc at risk” in the fellow eye (Fig. 1B) is also notable; this well-characterized risk factor (arguably requisite) for nonarteritic AION (6) has been postulated to apply to AION in ICAD (5). The findings in this particular case are consistent with the hypothesis that this common anatomic predisposition is important for the clinical manifestation of AION in the setting of ICAD. Albeit rare, ICAD should be included in the differential for painful AION, and early recognition is critical. Further studies may provide valuable insights into the pathogenesis of more common forms of AION. e731 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Correspondence FIG. 1. Initial presentation of anterior ischemic optic neuropathy secondary to internal carotid artery (ICA) dissection. A. Color fundus photograph of the right eye shows pallid optic nerve edema, most prominent nasally. B. Color fundus photograph of the left eye demonstrates a crowded disc. C–E. Computed tomography angiography images in coronal (C), sagittal (D), and axial (E) planes. Coronal and sagittal views demonstrate a tapering of the angiographic signal within the right ICA (arrows), and the axial view shows crescentic narrowing of the angiographic signal within the ICA lumen (arrow) representing thrombus within the false lumen. FIG. 2. Follow-up fundus photography and perimetry. A. Color fundus photograph obtained 1 month after initial presentation of the right eye demonstrates resolution of optic nerve edema and pallor that spares the inferotemporal sector. B. Color fundus photograph of the left eye demonstrates an unchanged crowded optic disc. C and D. Automated perimetry (Humphrey SITA 30-2) performed 6 months after initial presentation shows severe constriction in the right eye with a superior island of relatively preserved field (C) and normal responses in the left eye (D). Pattern standard deviation plots (left) and gray scale plots (right) are depicted. e732 Lains et al: J Neuro-Ophthalmol 2021; 41: e731-e733 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Correspondence STATEMENT OF AUTHORSHIP Category 1: a. Conception and design: I. Lains, and E. D. Gaier; b. Acquisition of data: J. D. Diaz, J. W. Gittinger, and E. D. Gaier; c. Analysis and interpretation of data: I. Lains, J. D. Diaz, J. W. Gittinger, and E. D. Gaier. Category 2: a. Drafting the manuscript: I. Lains; b. Revising it for intellectual content: J. D. Diaz, J. W. Gittinger, and E. D. Gaier. Category 3: a. Final approval of the completed manuscript: I. Lains, J. D. Diaz, J. W. Gittinger, and E. D. Gaier. REFERENCES 1. Debette S, Leys D. Cervical-artery dissections: predisposing factors, diagnosis, and outcome. Lancet Neurol. 2009;8:668– 678. Lains et al: J Neuro-Ophthalmol 2021; 41: e731-e733 2. 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