internal carotid artery dissection

see also:

• stroke (CVA)

• carotid dissection is an uncommon event occurring in ~2 in 100,000 population per annum
• along with vertebral artery dissection, it accounts for ~20% of ischaemic stroke (CVA) in young adults
• most common age is the mid-forties
• extracranial carotid dissections typically occur >=2 cm beyond the bifurcation (at level of the skull base)
• intracranial carotid dissections are most frequent in the supraclinoid segment
• 10% are bilateral
• 14% have aneurysmal dilatation

• headache (~65%) - this is usually gradual onset but of sudden onset in 20%
• other features are much more variable:
  • ant/lateral neck pain (~40%)
  • Horner's syndrome (~25% but usually partial without anhidrosis)
  • tinnitus
  • audible bruit
  • transient monocular blindness (8%)
  • retinal artery occlusion
  • ischaemic optic neuropathy
  • transient ischaemic attack (TIA) (~20%)
  • ischaemic stroke (CVA) (~50%)
  • subarachnoid haemorrhage (SAH) (~1%)

• mechanical trauma in prior month - often minor (~30% cases)
  • sports, yoga
  • chiropractic neck manipulation
  • amusement park rides
• Valsalva events:
  • childbirth
  • coughing
  • sneezing
  • sexual intercourse
• predisposing factors:
  • fibromuscular dysplasia (FMD) is present in 15-20%
  • other connective tissue (CT) disorders although very few appear to have a well defined genetic cause

• if sudden onset headache, Mx initially as per suspected subarachnoid haemorrhage (SAH)
• if clinical features suggest dissection then consider:
  • urgent MRA or CT angiography (both have similar sensitivity and specificity for dissection)
  • signs include:
    • long tapered arterial stenosis
    • a tapered occlusion
    • a dissecting aneurysm (pseudoaneurysm)
    • an intimal flap
    • a double lumen
    • an intramural hematoma

• if acute ischaemic stroke (CVA) without subarachnoid haemorrhage (SAH) within 3-4hrs onset is present, consider thrombolysis - although this is quite controversial, may increase extension of the dissection, and risks may exceed the benefits
• other patients with [stroke]] and without subarachnoid haemorrhage (SAH):
  • if large ischaemic area or intracranial dissection
    • avoid anticoagulants as risk of bleed or subarachnoid haemorrhage (SAH)
    • consider antiplatelet agents 3-6 months to prevent further stroke (CVA)
  • if extracranial dissection and small stroke area and no SAH:
    • consider anticoagulation or antiplatelet Rx for 3-6 months
• if extracranial, consider vascular opinion for repair or stenting, particularly if recurrent transient ischaemic attack (TIA) on antiplatelet Rx
• avoid:
  • contact sports
  • chiropractic neck manipulation
  • any activity that involves abrupt rotation and flexion-extension of the neck

• extracranial carotid dissection:
  • >70% have excellent recovery
  • 10-25% have major disabling neurologic deficits
  • 5-10% die
  • most dissecting extracranial aneurysms do not resolve with angiographic follow-up
  • residual headache may indicate persistent vascular abnormalities
  • ~1% recur annually
  • 0.3% recurrent stroke risk per annum over next 4 years
  • 0.6% recurrent stroke risk per annum over next 4 years
• intracranial carotid dissection:
  • ~33% have recurrence of neurologic events over next 8yrs