VIDEO
Risk factors and clinical presentation of craniocervical arterial dissection
(Doctors only)
Cervical Arterial Dissection
Arterial dissection is probably an under-recognized stroke mechanism.
PATHOLOGY
. Dissection occurs due to an intimal tear in the vessel wall and the formation of an intramural hematoma, sometimes associated with a pseudoaneurysm.
. Flow may be obstructed by compression of the lumen by the wall hematoma, or by intraluminal clot.
. Distal embolization from the area of injury downstream into the intracranial circulation is probably the most common stroke mechanism.
. In the internal carotid artery, dissection usually occurs 2 or more cm distal to the carotid bifurcation, and in the vertebral artery at the C1–2 level where the artery leaves the transverse canal of the axis bone. Intracranial dissections can also occur but are less common.
. Neck or head trauma and chiropracticmanipulation are known precipitating factors. Motor vehicle accidents with whiplash or seatbelt injuries to the neck are probably the most common cause seen in most hospitals. However, many people with cervical artery dissections do not have clear precipitating events
. Fibromuscular dysplasia and heritable arteriopathies such as Ehlers-Danlos syndrome predispose to arterial dissections, but most individuals do not have underlying arterial pathology.
DIAGNOSIS
. Ischemic stroke or TIA is the usual presenting symptom.
. A history of neck, facial, or head pain in patientwithout strong risk factors for vascular disease points toward the diagnosis.
. Horner’s syndrome may occur because of injury to sympathetic fibers lying on the outside of the carotid artery wall.
. Subarachnoid hemorrhage can occur if the dissection occurs or extends intracranially, because there are only two layers in the vessel wall, compared to three extracranially.
TESTING
When dissection is suspected, diagnostic testing should go beyond routine carotid ultrasound andMR angiography. Carotid ultrasound tends to focus at the carotid bifurcation and thus may not detect dissection, which is often located more rostrally. MRA detects large dissections but not a subtle intimal tear and flap.
Better diagnostic tests:
. MRI T1 sequence with fat suppression of the neck – Talk to your radiologist to be sure they know that dissection is suspected.
Hematoma in false lumen is bright.
. CT Angiogram – A good CTA can give information similar to DSA.
. Digital subtraction angiogram (DSA) – Find characteristic tapering lumen, rarely pseudoaneurysm, in locations usually not associated with atherosclerosis. Though considered a gold standard, sometimes it is not clear whether the abnormality is due to dissection or atherosclerosis.
Several diagnostic methodologies might be necessary to conclude that an artery has a dissection.
THERAPY
. Anticoagulation for 3-6 months has been the traditional medical therapy, since the mechanism of cerebral infarction is probably most often due to thromboembolism, though there are no randomized trials to support anticoagulation.
. The risk of stroke/TIA recurrence is low (+ or – 1.5% per year). Whether antiplatelet agents are sufficient remains uncertain.
. Most of the time, dissected arteries heal over time, leaving variable degrees of residual stenosis.
. Sometimes dissection is treated by endovascular or surgical means, though these interventions are not needed in most cases. The reasons for interventions include expanding pseudoaneurysm, or recurrent symptoms due to either hemodynamically significant stenosis or recurrent embolization. Stents can expand the lumen and detachable coils can be placed in the pseudoaneurysm.
