Neck Vessels / Dissection of the Carotid Artery

Top: Magnetic resonance angiography of right carotid artery dissection 2 cm from bifurcation (on left side). Bottom: Magnetic resonance angiography of right carotid artery dissection with clot in the wall (on left side). Dissection stops below skull base. Images contributed by Philip Kousoubris, MD.



Arterial dissection of the carotid arteries occurs when a small tear forms in the innermost lining of the arterial wall. Blood can enter into the space between the inner and outer layers of the vessel, causing stenosis or complete occlusion. Blood clots, or emboli originating from the dissection are thought to be the cause of infarction in the majority of cases of stroke in the presence of carotid artery dissection.

Carotid arterial dissections can be categorized as traumatic or spontaneous. Traumatic dissection is the result of either external mechanical injury, like blunt trauma, or trivial trauma that is related to a movement or abrupt change in head position, and sometimes strenuous physical exertion. Spontaneous dissections have no definitive precipitating factor, however they may be associated with systemic hypertension, connective tissue disorders, smoking, diabetes, oral contraceptives, a family history of cerebral infarction or cerebral and abdominal aortic aneurysms.

The signs and symptoms of carotid artery dissection may be divided into two categories:
Ischaemic
Decreased pupil size with drooping of the upper eyelid
Transient vision loss
Ischemic stroke

Non-ischaemic
Headaches
Neck pain

Recognizing a dissection early is essential because prompt anticoagulant therapy and endovascular repair greatly minimize the patients risk of infarction/stroke, neurologic disability, and death. Cervical arterial dissections are relatively rare. The combined incidence of both vertebral and carotid dissections is estimated to be 2.6 cases per 100,000 population. However, cervical arterial disections are the underlying reason in as many as 20 percent of the ischemic strokes that occur in patients 30 to 40 years old.

Nearly all imaging modalities have been used to demonstrate cervical arterial dissections. In the past conventional catheter angiography has been the standard for the diagnosis of arterial dissection, however increasing reliance has been placed on reconstructed cross-sectional imaging techniques, including CT scanning and MR angiography because of the noninvasive nature of these modalities. The many advantages of MRA's has made this the preferred method for the initial screening and evaluation of patients with suspected arterial dissection.