Arterial Dissection (Carotid, Vertebral)
Cervicocerebral Arterial Dissection (carotid and vertebral arteries)
Pathogenesis
- Arterial dissection arises from trauma to the arterial wall.
- The arterial wall layers separate, which creates a false lumen.
- The false lumen becomes the nidus for clot formation (intramural hematoma).
- The clot can then cause stroke through a variety of pathophysiological mechanisms, including vessel narrowing or obstruction and aneurysm formation (which can host thrombi or dissect).
Demographics
- Cervicocerebral arterial dissection accounts for 20% of strokes in patients < 45 years old.
- Although historically, it is reported that internal carotid arterial dissection is more common than vertebral artery dissection, many silent vertebral artery dissections are now being discovered on imaging and so the relative prevalence of these types of dissection are changing.
Arterial Anatomy
Arterial Wall Layers ("IMA"):
- Intima (the innermost layer)
- Media (the middle muscular layer)
- Adventitia (the outermost layer).
- Tear in the wall of an artery leads to a intramural hematoma but debate surrounds whether it is tear in the Media or the Intima that most commonly causes dissection.
Common Modifiable Risk Factors for Cervical Arterial Dissection
- Trauma: Major (eg, Motor Vehicle Accident), Minor (Cervical Neck Manipulation)
- Hypertension
- Oral Contraceptives
Genetic Risk Factors for Cervical Arterial Dissection
- Connective Tissue Disorders
- Fibromuscular dysplasia
- Marfan syndrome
- Ehlers-Danlos syndrome
- Alpha-1-Antitrypsin deficiency)
- Pro-thrombotic disorders
- Hyperhomocysteinemia
- Migraine)
References