Extracranial vascular disease refers to carotid and vertebral artery stenosis. These major vessels bring blood to the brain. These vessels become stenosed as their inner diameter is reduced by the presence of plaque. Plaque forms through the deposition of cholesterol and other substances. This process is called atherosclerosis. The plaque is a dynamic element as it may thicken, ulcerate, send small pieces of clot to distal intracranial vessels, and ultimately completely occlude the vessel. As the stenosis progresses, less blood irrigates the brain. Under certain flow-related circumstances, ischemia and stroke may occur.

Symptoms
Carotid stenosis, also referred to as carotid artery disease, may present which transient neurological deficits of short duration (transient ischemic attack) or an established neurological deficit (cerebral vascular attack). Both of these conditions are referred to as strokes. A transient ischemic attack should be considered as a medical emergency even if symptoms completely resolve. It may announce an imminent stroke with potentially permanent damage.

Symptoms include transient blindness in one eye, transient numbness/tingling or weakness of face, arm, leg, difficulty speaking or understanding others, confusion, sudden and severe headache.

The vertebral arteries irrigate mostly the cerebellum and brain stem. Symptoms related to vertebral artery disease may include numbness/tingling or weakness occurring bilaterally, double vision (diplopia), vision field defect, difficulty pronouncing words (dysarthria), and dizziness.

 A thorough investigation is required when a patient presents symptoms suggesting a stroke. Blood work-up with detailed evaluation of hypercoagulable conditions and cholesterol levels should be done. An electrocardiogram should be done to rule-out arythmia as a potential cause of stroke. Heart ultrasound may also be indicated to rule-out a potential source of tissue (emboli) that can gain the brain vessels through the blood stream.

Evaluation of carotid artery disease is performed initially through duplex doppler ultrasound which serves as a screening test. Carotid CT angiography and MRI angiography are used in many centers to image the plaque and the resultant stenosis. However, the gold-standard remains a conventional angiography.

Treatment depends on numerous factors including the presence or absence of symptoms, the degree of stenosis and the patient’s overall condition. Medical treatment may be sufficient is some asymptomatic patients or those with small stenosis. Surgery has proven to benefit some particular patient populations notably those with arteries narrowed by 70 percent or more. Carotid endarterectomy consists in removing the plaque responsible for the stenosis.
Endovascular techniques have also been developed to treat carotid artery disease. Carotid dilatation with balloons (angioplasty) and/or stenting may be performed to open the narrowed carotid.
Regarding treatment of symptomatic vertebral artery atherosclerosis, various surgical options exist. The proximal part of the vertebral artery can be sewn onto (transposed) the common carotid artery. Also, a bridge can be created with a vascular graft to bypass the site of most severe stenosis. Although vertebral endarterectomy has been described, it is rarely performed. Interventional neuroradiologists may also treated selected patients with vertebral artery stenting.
Addressing the causative factors is essential in the management of extracranial vascular disease. High blood pressure and diabetes must be well controlled. Patients should be encouraged to stop smoking, exercise regularly, and eat a healthy diet.