Usually, patients will present with recent stroke (slurred speech, cranial nerve deficits, limb weakness, or visual disturbances), which either have resolved or should be expected to improve within 48 hours, otherwise known as a transient ischemic attack. Typically, history and physical examination are notable for a patient in their 70s and 80s because they may have a history of smoking, high lipid profile, sedentary lifestyle. It is imperative to realize that carotid artery atherosclerotic disease is not a segmental disease; rather it has the propensity to involve other arteries in the human body. Of concern are the coronary arteries. Hence, it is prudent for this patient to undergo a cardiac evaluation should surgical intervention be contemplated in treating the degree of stenosis.

Evaluation should include but not be limited to a thorough physical examination. The physical should be coupled with diagnostic imaging (computed tomography scan of the head), followed by telemetry floor admission, as only a third of ischemic strokes are due to carotid artery disease. The remaining is due to the cardiac embolic phenomenon. Thus, consultation with a stroke specialist like a neurologist, as well as a cardiologist, is of paramount importance.

Regarding diagnosing carotid artery stenosis, one usually starts with the least invasive, inexpensive test, such as Carotid Duplex. This examination typically shows a high-resistance signal in the carotid bulb and the very proximal internal carotid artery. Distally, there are no Doppler signals audible in the carotid artery. As a confirmatory test, some form of contrast examination such as digital subtraction arteriography, magnetic resonance arteriography (MRA), or computed tomographic (CT) arteriography is required to confirm the diagnosis and plan a surgical approach. Gadolinium-enhanced MRA is better for differentiating high-grade stenosis than the time of flight which overestimates the stenosis in some times. Conventional angiography is the gold standard for the diagnosis.

Acute symptomatic carotid occlusion should be treated with urgent revascularization in select cases with an immediate presentation. This can be accomplished with carotid endarterectomy (CEA) or interventional techniques, including thrombolysis. In the setting of chronic total internal carotid artery occlusion (ICA) occlusion, medical management is preferred over revascularization. However, several special clinical indications exist for procedural intervention. Ipsilateral hemodynamic symptoms in the setting of ipsilateral ICA occlusion and contralateral ICA stenosis may benefit from contralateral ICA revascularization to ameliorate hemodynamic insufficiency. Ipsilateral embolic symptoms in the setting of ipsilateral ICA occlusion and ipsilateral external carotid occlusion (ECA) stenosis may be treated with ipsilateral ECA revascularization to eliminate the source of embolization, which occurs via enlarged ECA collaterals; ligation of the ipsilateral ICA also eliminates a source for embolization. Finally, ipsilateral hemodynamic symptoms in the setting of a patent contralateral carotid system, ipsilateral ICA occlusion, and ipsilateral ECA stenosis indicate ipsilateral ECA revascularization to improve ipsilateral hemodynamic flow.[8][9][10][11]

For patients with symptomatic carotid occlusion (50-99%), if carotid endarterectomy was done within two weeks of symptoms, the number needed to treat for preventing one stroke is 5. The number needed to treat increases to 125 if it has done more than two weeks of symptoms of stroke onset. CEA is beneficial if the symptoms are non-disabling, with no tandem stenoses, high-grade stenosis. CEA can be deferred if the stroke is too big, contralateral carotid occlusion, hemodynamic instability, and contralateral laryngeal palsy is a relative contraindication. There is more myocardial infarction associated with CEA. 

Carotid artery stenting (CAS) is preferred in symptomatic carotid occlusion (50-99%) with multiple comorbidities, tracheostomy, patients with prior neck radiation, or dissection. Usually, there is an increased risk of stroke after the CAS. Due to the advancement of the stents and technique, CAS is comparable to CEA in most instances. Carotid revascularization for primary prevention of stroke (CREST-2) study is ongoing and will shed more light on this important area.

The differential diagnosis of carotid artery stenosis may include:

• Carotid artery dissection[12]
• Fibromuscular dysplasia[13]
• Valvular heart disease especially aortic valve stenosis
• Arrhythmias such as atrial fibrillation[14]
• Mural thrombosis
• Takayasu vasculitis[15]
• Giant cell vasculitis
• Migraine[16]

There are no specific criteria for surveillance of patients with chronically occluded ICA, nor are there criteria to specify the degree of ECA stenosis by duplex ultrasound. A reasonable regimen is to follow the patient clinically every six months to a year, with or without a duplex study. The development of symptoms indicates investigation with imaging of some kind to see if cerebrovascular revascularization is indicated.

The management of patients with carotid artery stenosis is with an interprofessional team that consists of a nurse practitioner, primary care provider, internist, vascular surgeon, an interventional radiologist, and a neurologist. When a patient is discovered to have carotid stenosis, a referral should be made to the neurologist who can determine if treatment is required. Today, the carotid stenosis can be managed via surgery or stenting; both have similar outcomes in the short term. The treatment also dramatically reduces the risk of a future stroke.[17]