26: CAROTID ARTERY DISSECTION

PATIENT STORY

A 30-year-old man was involved in a motor vehicle accident. He had rib fractures, a pulmonary contusion, and mild neck pain, but no other injuries. He denied amaurosis fugax, weakness, numbness, paralysis, paresthesias, speech disturbance, or gait disturbance. On the upper cuts of a chest computed tomography (CT), a dissection of his right internal carotid artery (ICA) was seen, and a focal dissection starting just distal to the right carotid bulb and extending through the cervical ICA was confirmed on a subsequent CT angiogram of the neck.

EPIDEMIOLOGY

• Dissection causes less than 2% of ischemic strokes, but up to 20% of the ischemic strokes in patients less than 50 years old are related to dissection. It is the second leading cause of cervical carotid disease, behind atherosclerosis.^{1,2, and 3}

ETIOLOGY AND PATHOPHYSIOLOGY

• Carotid dissection, as in other vascular beds, starts when a tear in one or more layers of the arterial wall occurs, allowing blood to separate the layers and form a thrombosis or a patent false lumen.

• In the cervical carotid artery, the dissection often occurs after trauma causing a whiplash-type motion.

• Carotid dissections may be spontaneous as well, though often a careful history will reveal a temporally associated trivial trauma such as a cough or neck rotation.

• Predisposing factors such as Marfan disease, Ehlers-Danlos type IV syndrome, or fibromuscular dysplasia may be present in these cases, but these connective tissue disorders are implicated in only 5% of spontaneous dissections.⁴

• The location of the dissection is usually at a mobile point of the artery, such as distal to the carotid bulb.

• Carotid dissection may also present as an extension of aortic dissection (Figure 26-1).

DIAGNOSIS

• Diagnosis is often made incidentally, perhaps by imaging done at the time of multiple trauma.

• Carotid dissection can be detected with duplex ultrasound (Figure 26-2), CT angiography, magnetic resonance (MR) angiography, or catheter angiography.

CLINICAL FEATURES

• When found incidentally, many carotid dissections may be asymptomatic.

• If symptomatic, in addition to cerebral ischemia, carotid dissection can present with unusual or pathognomonic symptoms.

• Headache and neck pain are the most common nonischemic symptoms.

• A Horner syndrome can result from ...