Carotid artery dissection is a separation of the layers of the artery wall supplying oxygen-bearing blood to the head and brain and is the most common cause of stroke in young adults. (In vascular medicine, dissection is a blister-like de-lamination between the outer and inner walls of a blood vessel, generally originating with a partial leak in the inner lining.)Dissection may occur after physical trauma to the neck, such as a blunt injury (e.g. [Source: Wikipedia ]