The vertebral arteries and internal carotids are the two main pairs of arteries which supply blood to the brain, which in conjunction with the communicating arteries, form the circulation network known as the ‘Circle of Willis’.
The arrangement of the brain’s arteries into the Circle of Willis creates redundancies or collaterals in the cerebral circulation. If one part of the circle becomes blocked or narrowed or one of the arteries supplying the circle is blocked or narrowed, blood flow from the other blood vessels can often preserve the cerebral blood perfusion well enough to avoid the symptoms of ischemia.
The right and left posterior cerebral arteries arise from the basilar artery (part of the Circle of Willis), which is formed by the left and right vertebral arteries. The vertebral arteries arise from the subclavian arteries which in turn branch off the aorta, delivering oxygenated blood from the heart.
Vertebral artery dissection is a dissection (a flap-like tear) of the inner lining of the vertebral artery. After the tear, blood enters the arterial wall and forms a blood clot which impedes blood flow. Vertebral dissection may occur spontaneously or after physical trauma to the neck, such as a blunt injury or excessive neck movement. 1–4% of spontaneous cases have a clear underlying connective tissue disorder affecting the blood vessels.
Symptoms of vertebral artery dissection include a gradually developing head ache.
Obstruction of blood flow through one of the vertebral arteries may lead to dysfunction of part of the brain supplied by the artery due to insufficiency in blood supply. This happens in 77–96% of cases and may be temporary. The vertebral artery supplies the part of the brain that lies in the back of the skull and so problems may include unsteadiness or lack of coordination due to involvement of the cerebellum, others may develop visual loss (on one side of the visual field) due to involvement of the visual cortex in the occipital lobe. Some may experience difficulty speaking or swallowing however this occurs in less than a fifth of cases and occurs due to dysfunction of the brainstem.
Artery dissections cause only 2% of all strokes however it causes a quarter of strokes in our young to middle age population. Emergency medical treatment is required with ongoing rehabilitation if neurological symptoms persist.
If you think that you have the symptoms of a vertebral artery dissection, go to emergency immediately. For more information on rehabilitation following a vertebral artery dissection, please contact our neurological physio centre.