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Carotid Artery Dissections


Carotid artery dissections have been increasingly recognized over the last several decades. Their precise incidence is hard to estimate, but it ranges from 2.5 to 3/100,000 population. They account for 2% to 3% of first-time strokes but up to 20% of strokes in patients younger than 30 years. They have been reported in children and at times are bilateral. In the setting of major trauma with liberal use of computed tomography (CT) scanning, they are recognized in 1.7% of cases. Diagnosis is often considered late after a neurologic event or not at all. Treatment remains problematic. Carotid artery dissection is sometimes thought to be a spontaneous event, which merely means that we have not yet fully understood the pathophysiology of this problem.

Clinical Pathophysiology

Carotid artery dissection can occur as a result of clear-cut stretch–traction–rotation injury ( Figure 1 ) or direct compression between the angle of the jaw and the transverse vertebral processes ( Figure 2 ). In the setting of significant trauma, such as a motor vehicle accident or a direct blow to the neck, cranial–cervical CT images are typically obtained and a rapid diagnosis follows. However, repetitive stress injury, whereby minor stresses of a subcritical nature accumulate and cause a dissection, is often associated with a delay in diagnosis.

FIGURE 1, Stretch–traction–rotation forces cause intimal injury as the postbulbus internal carotid artery crosses the transverse processes of the second and third cervical vertebrae.

FIGURE 2, Direct internal carotid artery injury results from compression of the artery between the angle of the mandible and the upper cervical vertebrae.

A number of precipitating events have been cited in case reports, including violent coughing, forceful emesis, heavy exercise, looking over one’s shoulder while driving, and chiropractic manipulation. Such reports are anecdotal at best. Intraoral trauma, typically in a child falling with a pencil or other object in his or her mouth, also has been reported. Certain diseased arteries, such as in patients with fibrodysplasia or connective tissue disorders, have a propensity to dissect. Many other arteriopathies and conditions are occasionally noted in conjunction with carotid artery dissections ( Box 1 ).

BOX 1
Arteriopathies and Conditions Associated with Carotid Artery Dissection

  • Fibrodysplasia

  • Ehlers–Danlos syndrome type IV

  • Marfan’s syndrome

  • α 1 -Antitrypsin deficiency

  • Type 1 collagen point mutation

  • Migraine

  • Cystic medial necrosis

  • Low-lying carotid bifurcation

  • Coils, kinks, loops

  • Giant cell arteritis

  • Temporal arteritis

  • Irradiated blood vessels

  • Moyamoya disease

  • Neck manipulation

The intimal disruption leading to an intramural hematoma can narrow the lumen and reduce flow or totally occlude the carotid artery. The disrupted intima can also serve as a nidus for deposit of platelet fibrin, which can subsequently embolize. Finally, the dissected and weakened artery can produce a pseudoaneurysm. Pseudoaneurysm typically occurs in the distal internal carotid artery at the skull base. Regardless of the etiology, dissected carotid arteries remain an important clinical entity and are often associated with significant diagnostic and therapeutic challenges.

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