Neuro-Ophthalmic Presentations of Common Carotid Artery Occlusion: A Case Series

Common carotid artery (CCA) occlusion (CCAO), as opposed to internal carotid artery (ICA) occlusion (ICAO), is a rare entity with a reported incidence of only 0.4%-3% in patients with symptomatic cerebrovascular ischemic disease (1,2). The blood supply to the eye derives from the ICA, and hence, a CCAO can present with ischemic ocular symptoms (e.g., amaurosis fugax, branch or central retinal artery occlusion (CRAO), ophthalmic artery occlusion, or ocular ischemic syndrome). We report 2 cases of CCAO with neuro-ophthalmic presentations. To the best of our knowledge, this is the largest such series of patients in the English language ophthalmic literature.

Clinical Correspondence Section Editors: Robert Avery, DO Karl C. Golnik, MD Caroline Froment, MD, PhD An-Guor Wang, MD Neuro-Ophthalmic Presentations of Common Carotid Artery Occlusion: A Case Series Jason Zehden, Shruthi Harish Bindiganavile, MD, Nita Bhat, MD, Andrew G. Lee, MD C ommon carotid artery (CCA) occlusion (CCAO), as opposed to internal carotid artery (ICA) occlusion (ICAO), is a rare entity with a reported incidence of only 0.4%–3% in patients with symptomatic cerebrovascular ischemic disease (1,2). The blood supply to the eye derives from the ICA, and hence, a CCAO can present with ischemic ocular symptoms (e.g., amaurosis fugax, branch or central retinal artery occlusion (CRAO), ophthalmic artery occlusion, or ocular ischemic syndrome). We report 2 cases of CCAO with neuro-ophthalmic presentations. To the best of our knowledge, this is the largest such series of patients in the English language ophthalmic literature. CASE 1 A 79-year-old white man presented with transient, painless, monocular vision loss in the left eye that occurred 4–5 times over a period of 2 weeks. He then developed recurrent episodes of right upper extremity weakness lasting minutes at a time consistent with a transient ischemic attack (TIA). He reported some left temporal pain with these episodes. The past medical history was significant for Merkel cell carcinoma of the left neck status after resection and previous external beam radiation therapy to the neck. He had previous hemodynamically significant left ICA stenosis that was treated with left ICA stenting. The remainder of the past medical, surgical, social, and allergy histories were noncontributory. His medications were apixaban, aspirin, atorvastatin, carvedilol, levothyroxine, losartan, nifedipine, and venlafaxine. He was admitted to the hospital for stroke evaluation. Serum C-reactive protein was normal at 0.5 mg/dL, and erythrocyte sedimentation rate was elevated at 66 mm/hr. Baylor College of Medicine (JZ, AGL), Houston, Texas; Department of Ophthalmology (SHB, NB, AGL), Blanton Eye Institute, Houston Methodist Hospital, Houston, Texas; Houston Methodist Research Institute (AGL), Houston Methodist Hospital, Houston, Texas; Departments of Ophthalmology (AGL), Neurology, and Neurosurgery, Weill Cornell Medicine, New York, New York; Department of Ophthalmology (AGL), University of Texas Medical Branch, Galveston, Texas; University of Texas MD Anderson Cancer Center (AGL), Houston, Texas; Texas A and M College of Medicine (AGL), Bryan, Texas; and Department of Ophthalmology (AGL), the University of Iowa Hospitals and Clinics, Iowa City, Iowa. The authors report no conflicts of interest. Address correspondence to Andrew G. Lee, MD, Blanton Eye Institute, Houston Methodist Hospital, 6560 Fannin Street Suite 450, Houston, TX 77030; E-mail: [e-mail] e734 MRI of the head revealed microvascular ischemic changes. Computed tomography (CT) angiography (CTA) of the head and neck showed proximal occlusion of the left CCA (Fig. 1). There was a carotid stent in the mid to distal left ICA with reconstitution of flow at the carotid bifurcation distal to the stent. There was severe narrowing of the proximal to mid left cervical ICA and mild narrowing of the distal left cervical ICA. Carotid duplex revealed complete occlusion of the left CCA and less than 50% stenosis in the left ICA with retrograde flow in the left external carotid artery (ECA) feeding the left ICA with diminished flow in the left ICA. On examination, his visual acuity was 20/25 in both eyes. There was no ptosis. The pupil examination was normal pupils without anisocoria or relative afferent pupillary defect (RAPD). No Horner syndrome was noted. Slit-lamp examination showed posterior chamber intraocular lenses bilaterally. Extraocular motility and intraocular pressure examinations were normal in both eyes. Fundus examination showed a posterior vitreous detachment and dot hemorrhage in the left eye. The right fundus examination was normal. A right-sided temporal artery biopsy (TAB) was negative and performed contralateral to the left eye symptoms because the blood flow was reversed in the left ECA and was now feeding the left ICA. The patient had received empiric steroids before the TAB that were tapered. The amaurosis fugax and contralateral hemispheric TIA were believed to be due to the CCAO with retrograde ECA flow supplying the ICA. The patient then underwent a left subclavian to ICA bypass with complete resolution of symptoms. CASE 2 A 62-year-old white man presented with acute, painless vision loss in his right eye to count fingers. He had no previous vasculopathic risk factors. Past medical, surgical, social, family, and allergic histories were noncontributory. He was admitted to the hospital, and CT of the head was normal. A CTA of the head was normal, whereas a CTA of the neck showed occlusion of the right CCA. There was greater than 90% stenosis of the right carotid bifurcation and reconstitution of flow in the right ICA and ECA. He received Tissue plasminogen activator because he had presented within 2 hours of onset of his symptoms. His Zehden et al: J Neuro-Ophthalmol 2021; 41: e734-e737 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Correspondence The pupils measured 5.5 mm and were reactive to 3 mm but there was a right RAPD. Slit-lamp examination was normal in both eyes. Ophthalmoscopy showed diffuse retinal whitening consistent with retinal ischemia with cilioretinal artery sparing and a cherry red spot consistent with a right CRAO (Fig. 2). No retinal embolus was identified. The left retina was normal. Erythrocyte Sedimentation Rate and C- Reactive protein were normal. A right subclavian to right carotid bypass was performed but the vision remained unchanged in the right eye. DISCUSSION FIG. 1. A 3-dimensional computerized tomography angiogram of the neck showing complete occlusion of the CCA on the left. CCA, common carotid artery. visual acuity was 20/70 eccentrically in the right eye and 20/ 20 the left eye. Confrontation field was peripherally constricted in the right eye and normal in the left eye. Zehden et al: J Neuro-Ophthalmol 2021; 41: e734-e737 The clinical features of CCAO are less widely reported than the more common ICAO. Several case series have reported visual symptoms in CCAO (Table 1) (3–6). Amaurosis fugax seems to occur at a higher rate in CCAO in comparison with ICAO (5). One hypothesis that has been proposed for the higher rate of visual disturbances in CCAO in comparison with ICAO is that CCAO may lead to transient hemodynamic insufficiency of the retina caused by reduction in blood supply from both the ICA and ECA simultaneously while the rich anastomoses preserves the cerebral circulation relatively (5). Case one had previous neck radiation therapy for Merkel cell carcinoma that may have led to accelerated atherosclerosis causing the previous internal carotid stenosis and secondary CCAO. Case 2 had a CCAO treated with a subclavian to carotid bypass graft. Riles et al described 4 types of CCAO based on patency of the distal ECA and ICA (Fig. 3) (11). The mechanisms of common carotid occlusion causing cerebrovascular and ocular symptoms could be either from hypoperfusion or from thromboembolism. Cerebral perfusion in cases with complete CCAO is usually maintained by collaterals from the ECA, the vertebral system, or the contralateral carotid system (7). Hemodynamic factors and autoregulatory failure paired with insufficient collaterals may result in transient ischemic symptoms from a steal phenomenon (6), as was seen in case 1 (8). Cerebrovascular emboli could also result from the stump syndrome, which although usually caused by emboli from ICAO, could also be due to an occluded CCA stump acting as an embolic source throwing off emboli into distal ICA and cerebral circulation, which was possibly the cause in case 2 (9). In summary, CCAO is an uncommon cause for ocular ischemic symptoms and signs. Surgical correction and bypass procedures are often needed to maintain cerebral perfusion through the ICA, as was performed in both of our patients. Ocular ischemic symptoms could arise from thromboembolic (stump syndrome) or from ocular hypoperfusion (steal phenomenon). Ophthalmologists should be aware that cervical carotid imaging should include the CCA, especially in patients with a history of previous carotid disease (e.g., severe stenosis, previous carotid stenting or endarterectomy, or occlusion). In addition, patients with ipsilateral ICA or CCA disease (e.g., ipsilateral visual loss e735 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Correspondence FIG. 2. Right eye showing diffuse retinal ischemia and cilioretinal sparing with a cherry red spot. Left fundus looks normal. TABLE 1. Previous CCAO case series with ocular symptoms Case Series Total Patients Patients With Ocular Symptoms Levine et al3 17 patients with CCAO 14/17 Keller et al4 7 patients with CCAO 4/7 Hoya et al5 Countee et al6 12 patients with CCAO (8 symptomatic and 4 asymptomatic) 137 patients with symptomatic ICAO 82 patients with ICAO 4/8 symptomatic 8/137 17/82 Description of Symptoms (# of Patients) (5) amaurosis fugax (2) bilateral visual blurring/loss (1) monocular visual disturbance (1) central visual loss + Hollenhorst plaque (1) vague decrease in vision (1) blurred vision (1) inferior quadrantanopia (1) ischemic optic neuropathy (2) visual field loss (1) vertical diplopia (4) amaurosis fugax and (1) persisting upper visual field defect (4) amaurosis fugax (8) amaurosis fugax (3) continuous monocular visual disturbance (17) amaurosis fugax CCAO, common carotid artery occlusion; ICAO, internal carotid artery occlusion. FIG. 3. Riles et al classification of CCAO (11). Type 1A, CCAO with patent ICA and ECA; type 1B, CCAO with a patent ECA and an occluded ICA; type 1C, CCAO with a patent ICA and an occluded ECA; type 2 involves a total CCA, ICA, and ECA occlusion (11). CCA, common carotid artery; CCAO, common carotid artery occlusion; ECA, external carotid artery; ICA, internal carotid artery. e736 Zehden et al: J Neuro-Ophthalmol 2021; 41: e734-e737 Copyright © North American Neuro-Ophthalmology Society. Unauthorized reproduction of this article is prohibited. Clinical Correspondence with contralateral hemisensory loss or hemiparesis) should undergo angiographic evaluation of the ICA and CCA including collateral formation before performing a TAB because the patient may be dependent on the superficial temporal artery as a collateral for intracranial perfusion. Patients with CCAO or ICAO may have retrograde flow from the ipsilateral ECA and a TAB in this setting might be dangerous and could cause an iatrogenic ischemic hemispheric stroke (10). 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