Carotid artery dissection, a tear in the inner lining of the artery wall, is a potentially life-threatening condition. The carotid arteries supply oxygen-rich blood to the brain, and any interruption in that supply can have very serious consequences, depending largely on the duration of such an interruption. However, dissection can and does occur without any immediate damage, and its early symptoms easily can be confused with those of less serious conditions.
Types of Dissection
Dissection of the carotid arteries is generally broken into two main categories: spontaneous and traumatic. Spontaneous dissection is unquestionably the most insidious of the two types, because its cause is almost always unknown, making it hard to diagnose. As its name indicates, traumatic dissection results from some external or internal damage to the neck and carotid arteries. As an example of internal trauma, carotid dissections have been reported as an extreme complication of severe pertussis (whooping cough). In those cases, the arterial injury was caused by uncontrolled episodes of paroxysmal coughing.
Types of Symptoms
The symptoms of carotid dissection are also divided into two categories: ischemic and non-ischemic. As discussed earlier, any interruption of blood flow to the brain is extremely serious and potentially deadly. Stroke and stroke-related symptoms fall into the category of ischemic symptoms, while non-ischemic symptoms are those not directly related to diminished or interrupted blood flow to the brain.
A tear in the inner lining of the carotid, according to MedlinePlus, allows blood to flow "in between layers of the blood vessel." This can lead to a narrowing of the artery, which reduces blood flow to the brain, or complete occlusion, which cuts off blood flow to the portion of the brain supplied by that artery. A full-blown stroke may occur shortly after the dissection. However, if blood flow continues, but at a diminished rate, the symptoms may include an impairment of vision that comes and goes, numbness, memory loss, change in consciousness, or pronounced weakness on one side of the body.
The non-ischemic symptoms of carotid dissection are less alarming and easily can be mistaken for those of other conditions. Non-ischemic symptoms include tinnitus, a ringing in the ears; Horner's syndrome, characterised by a constricted pupil, drooping eyelid and a sinking of the eyeball into the face; headache; and neck pain. Although a dissection at its outset may cause non-ischemic symptoms only, the condition could worsen and eventually progress into an ischemic event.
Incidence and Diagnosis
The incidence of carotid dissection---both spontaneous and traumatic---is very low, occurring in only 2.5 to 3 people per 100,000. Although a stroke or transient ischemic event (TIA) is a sign of interrupted blood flow to the brain, it can be caused by a wide variety of factors, of which carotid dissection is but one. The only way to conclusively diagnose this injury is through an arteriogram or angiogram.