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Vertebral artery dissection is the tearing of the wall of a vessel carrying blood to the brain. It can occur in either of the two branches of these neck arteries as a result of trauma, or can arise spontaneously as a consequence of connective tissue disease. When the vessel wall is torn, blood pools inside the artery and begins to clot. This process can block part of the brain's blood supply, with varying neurological problems occurring as a result. Given prompt treatment, patients often recover fully.
The two vertebral arteries branch from the lower neck and run up along the vertebrae into the skull. In the brain, they merge into the basilar artery, by which they eventually supply blood to areas like the cerebellar arteries. Dissection refers to abrupt tearing of the vertebral vessel's wall. This leads to hemorrhaging within the artery, and subsequent pooling of blood in a contained region of the blood vessel. Vertebral artery dissection seems slightly more common in men than in women, although clinical studies don't agree about the extent of gender differences.
Vertebral artery dissection can occur after neck trauma from violence or sudden movement, or it can arise spontaneously from various diseases. Traumatic causes commonly include whiplash injuries from automobile collisions, but even extreme extension of the neck during exercise or chiropractic treatment can result in tearing. As with complications due to dissection of the other main blood vessels of the neck — the carotid arteries — symptoms include classic neurological difficulties like head or neck pain, dizziness, and visual impairment.
The pathology of a vertebral artery dissection arises from the hemorrhage within the blood vessel. The main complication is caused by clotting contained in a portion of the artery, where blood accumulates in a pouch-like compartment. Major dissections can block a branch of the artery once they clot, cutting off the blood supply to parts of the brainstem or cerebellum. Sometimes blood can accumulate within the vessel, causing it to expand in a way that resembles an aneurysm, and risks rupture, though this is an uncommon event.
A small percentage of stroke cases are caused by vertebral artery dissection. While uncommon overall and among the elderly, this pathology accounts for up to a quarter of strokes in younger people. Once the blood inside the dissecting artery clots, there is the risk that a small fragment of the clot will break off into the bloodstream, causing an embolism by blocking a smaller vessel farther upstream in the brain. Vertebral artery dissection can be treated with the anti-clotting drugs heparin or warfarin for several months. A majority of patients recover within a few months of receiving treatment, and fatalities are relatively uncommon.