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.

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  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}

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  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.

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

  
  
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  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.

  
  
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  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

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

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