Symptomatic Carotid Artery Stenosis Presenting with Visual Field Deficits Managed via Transcervical Carotid Artery Revascularization

Symptomatic Carotid Artery Stenosis Presenting with Visual Field Deficits Managed via Transcervical Carotid Artery Revascularization
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doi:10.62055/symptomaticcarotidarterystenosis

INTRODUCTION

Welcome to the “Neuro Nuggets” column within the Journal of Medical Optometry (JoMO)!  This column aims to make neuro-ophthalmic disease more approachable by blending real-world clinical cases with evidence-based medicine.  The patient in this edition’s column features impressive visual recovery after carotid revascularization surgery.  For this edition, experts from vascular surgery and neuroradiology contributed to the case report below.  Enjoy!

 

CASE PRESENTATION

A 79-y.o. white male presented for evaluation complaining of trouble seeing in his peripheral vision while driving for the preceding two weeks.  He specifically had difficulty identifying the yellow lines on the road, mostly in the inferior left aspect of his visual field.  The patient also reported bumping into objects on the left side.  He denied any new or acute systemic symptoms.  The patient’s past medical history included prostate cancer and a prior prostatectomy three years prior to presentation without any further recurrence.

On examination, the patient’s best-corrected visual acuity was 20/25 in each eye, attributed to age-related nuclear sclerotic and cortical cataracts.  Color vision by Ishihara was intact in each eye.  Ocular motility evaluation was normal.  Confrontation visual field testing demonstrated possible left inferior constriction in each eye.  Slit lamp exam, intraocular pressure, and dilated fundus evaluation were normal in each eye.  The neuro-retinal rim of the optic disc was felt to be pink and intact without significant optic disc pallor/atrophy in either eye.

Automated Humphrey visual field (HVF) testing revealed an incongruous left inferior quadrantanopia, worse on the right eye compared to the left (Figure 1).  OCT imaging of the retinal ganglion cell layer did not demonstrate bilateral right- or left-sided loss, as would be seen in trans-synaptic retrograde degeneration.

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Figure 1. HVF at presentation demonstrating left inferior quadrantanopia.

 

MRI of the brain with and without contrast revealed areas of restricted diffusion and hyperintensity within the right occipital, right parietal, and right frontal lobe that were felt to be compatible with subacute cerebral ischemia (Figure 2).  CTA and MRA of the head and neck with and without contrast revealed severe stenosis to near occlusion of the right internal carotid artery (Figure 3).  Carotid duplex imaging of the vasculature of the neck (Figure 4) demonstrated increased peak systolic velocity 764 cm/s which correlated to >90% stenosis of the right internal carotid artery.

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Figure 2. MRI brain, axial T1 fluid-attenuated inversion recovery (FLAIR) image demonstrating subacute infarction at the right occipital-parietal lobe.

 

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Figure 3. CTA (left image) demonstrates severe stenosis at the origin of the cervical right ICA with filiform contrast in the severely narrowed lumen (yellow arrow). MRA shows similar findings of ICA stenosis in sagittal view (middle image with orange arrow) and coronal view (right image with red arrow).

 

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Figure 4. Carotid ultrasound doppler demonstrated increased peak systolic velocity (PSV) at the site of maximal ICA stenosis (arrow).

 

The patient was diagnosed with a subacute right-sided watershed infarction, and involvement of the right occipital and parietal lobes was felt to correlate with the left inferior quadrantanopia seen on HVF.  He was admitted for neurologic, vascular, and cardiovascular evaluation.  After discussing various management options, the patient and his care team decided to proceed with right transcervical carotid artery revascularization (TCAR).  The patient underwent his right TCAR procedure three days after the initial eye exam.

Post-operatively, the patient did very well.  His visual field deficit recovered (Figure 5) in the six month period after his vascular surgery.  He is maintained on low-dose aspirin and atorvastatin and does not have any significant residual neurologic deficits.

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Figure 5. HVF serial examinations demonstrating visual recovery following TCAR.

 

DISCUSSION

Visual recovery following acute cerebral infarction is an important concept for eye care providers to be familiar with.  A study from Zhang et al assessed 113 patients with homonymous hemianopia who presented within one month of injury and found that 55% of those patients spontaneously recovered.1   It is believed that chances for recovery following acute stroke diminish with longer time to initial presentation following symptom onset.  Visual recovery in patients with homonymous hemianopia mostly occurs in the first month after lesion onset, but some patients can demonstrate improvement even 3-6 months after (and some as far as 12 months after).1 Fortunately, the patient in this report presented about two weeks after symptom onset and demonstrated excellent visual recovery on serial perimetry following his carotid revascularization procedure.

In terms of paraclinical tests, conventional angiography has been traditionally considered the standard method for evaluating carotid stenosis. However, ultrasound doppler, CT angiography (CTA) and MR angiography (MRA) have been replacing conventional digital subtraction angiography (DSA) for diagnosis, reserving it for endovascular treatment.  Carotid doppler ultrasound may evaluate the appearance of the atheromatous plaque and can quantify changes in velocities. CTA and MRA images can be reformatted in multiple planes to delineate and characterize the plaque and to perform accurate measurements.

Carotid artery stenosis most commonly results from atherosclerotic disease that can lead to embolization and thrombosis resulting in neurologic events (e.g., transient ischemic attack, stroke). The treatment includes maximal medical therapy and possibly carotid revascularization for stroke risk reduction. The indications for surgical intervention of stenotic lesions are the same regardless of revascularization approach (carotid endarterectomy [CEA] versus carotid artery stenting [CAS] and transcervical carotid artery revascularization [TCAR]).2 The criteria for type of surgical intervention generally includes surgical accessibility, anatomy, and medical comorbidities. The gold standard operation (CEA) may not be a feasible option for a variety of reasons, most commonly for anatomic challenges (e.g. very high lesions), prior surgery and/or neck radiation, or high medical risk for anesthesia.3

CAS has been utilized as an alternative to CEA for high-risk patients, especially for high anatomic lesions. CAS and TCAR differ in many ways beyond just the approach, and the decision between them is multifactorial.  CAS is an endovascular procedure whereby the femoral artery is accessed, a sheath is advanced into the common carotid artery (CCA) traversing the aortic arch, and an embolic filter is placed above the lesion after crossing it prior to angioplasty and placing the stent. A patient can be completely awake for a CAS. TCAR is a hybrid procedure that requires an incision at the base of the neck and surgical exposure of the proximal cervical CCA. A sheath is then placed into the CCA, flow reversal is initiated for embolic protection prior to crossing the lesion, and the lesion is treated with angioplasty and stent. Both procedures require that a patient take clopidogrel (Plavix) for a period of time, and both are contraindicated in heavily calcified lesions. Anatomic limitations exist for both procedures, such as aorto-iliac occlusive disease or severe aortic arch disease limiting access for CAS, or a deep and/or short length CCA for TCAR. Contralateral disease may limit tolerance for flow-reversal in TCAR. CAS can be comfortably done on awake patients, but the surgical approach for TCAR may limit the tolerance for an awake procedure in a patient unfit for general anesthesia.

For the patient in this case report, he presented with a symptomatic carotid lesion that met criteria for intervention. Based on his imaging, his lesion was described as very tight and very high, at the base of C2 with exposure for repair approaching the dens (odontoid process). The risks for nerve injury are prohibitively high at this location (especially to the hypoglossal and glossopharyngeal nerves), and the decision was made to pursue a stent.  Importantly, he did not have excessive calcifications that would make a stent contraindicated. He anatomically met criteria for TCAR (CCA <5cm deep from the skin at the skin incision and >5cm CCA length from CCA exposure to lesion). In addition, with his symptomatic lesion, TCAR was chosen for the better embolic protection system (flow reversal) over a CAS filter.

The patient underwent an uncomplicated TCAR and recovered without issue and has since been seen in follow-up with a widely patent stent and no neurologic symptoms. He took clopidogrel (Plavix) for only 30 days after the procedure per protocol, and he now remains on low-dose aspirin. Follow-up is the same for CEA and stenting, with annual duplex and maintenance of medical therapy including ASA/statin.

 

CLINICAL PEARLS:

  • The discovery of visual deficits stemming from visual pathway lesions should trigger a prompt work-up that may uncover previously unidentified carotid artery stenosis.
  • Expedited surgical revascularization procedures in patients presenting with significant carotid artery stenosis can help to maximize the chance of recovery.
  • Interdisciplinary care and coordination is of paramount importance for patients presenting with visual pathway deficits and carotid artery stenosis.

 

REFERENCES

  1.  Zhang X, Kedar S, Lynn MJ, Newman NJ, Biousse V. Natural history of homonymous hemianopia. Neurology. 2006 Mar 28;66(6):901-5. doi: 10.1212/01.wnl.0000203338.54323.22. PMID: 16567709.
  2. Kashyap VS, King AH, Foteh MI, Janko M, Jim J, Motaganahalli RL, Apple JM, Bose S, Kumins NH. A multi-institutional analysis of transcarotid artery revascularization compared to carotid endarterectomy. J Vasc Surg. 2019 Jul;70(1):123-129. doi: 10.1016/j.jvs.2018.09.060. Epub 2019 Jan 6. PMID: 30622007.
  3. Columbo JA, Martinez-Camblor P, Stone DH, Goodney PP, O’Malley AJ. Procedural Safety Comparison Between Transcarotid Artery Revascularization, Carotid Endarterectomy, and Carotid Stenting: Perioperative and 1-Year Rates of Stroke or Death. J Am Heart Assoc. 2022 Oct 4;11(19):e024964. doi: 10.1161/JAHA.121.024964. Epub 2022 Sep 29. PMID: 36172943; PMCID: PMC9673728.

The authors have no financial disclosures, and no sponsorship or funding was involved in this work.

Boston VA Healthcare System | Boston, MA

Dr. Kane graduated from New England College of Optometry in 2015 and went on to complete an ocular disease/primary care residency at VA Boston Jamaica Plain from 2015-2016. He is currently an attending optometrist at VA Boston. His interests include clinical teaching, neuro-ophthalmic disease, retinal vascular disease, glaucoma, and ocular manifestations of systemic disease.

Boston VA, Department of Surgery | West Roxbury, MA

Dr Martin is a double-board certified practicing Vascular Surgeon at the Boston VA. She completed her training in General Surgery in 2011 and Vascular fellowship in 2013 at Harvard affiliated Beth Israel Deaconess Medical Center in Boston. She practices the full scope of Vascular Surgery, using both open and advanced endovascular techniques to treat arterial occlusive disease, aneurysms, and venous disease.

VA Boston Healthcare System | Boston, MA

V. Carlota Andreu Arasa, MD, PhD is an assistant professor in Radiology at Boston University School of Medicine and an experienced neuroradiologist.
Dr. Andreu obtained her medical degree and her PhD and Complutense University in Madrid, Spain, where she completed her Radiology Residency.
She trained at Boston University School of Medicine, where she completed her Neuroradiology fellowship and a Body imaging fellowship.

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