Clarification on treatment for ischemic stroke caused by extracranial/intracranial artery dissection

This forum made possible through the generous support of SDN members, donors, and sponsors. Thank you.

cyrushanleone

New Member
5+ Year Member
Joined
Oct 6, 2016
Messages
5
Reaction score
1
For ischemic strokes caused by extracranial/intracranial artery dissections, why is anticoagulation/antiplatelet therapy the main medical treatment? To me, it sounds counter-intuitive that you would anticoagulate a patient who has a dissection. I've also seen that if they are within the 4.5 hour waiting period, tPA should be given too? Why would you want to give tPA in this situation? Can someone clarify this a little more?

Members don't see this ad.
 
You kind of answered it yourself in your question. You have an ischemic stroke and you have a source. The dissection is likely causing thrombosis leading to emboli that caused the stroke. At that point, the risk of losing viable brain tissue outweigh the risk of bleeding. per the tPA, same thing.
 
You kind of answered it yourself in your question. You have an ischemic stroke and you have a source. The dissection is likely causing thrombosis leading to emboli that caused the stroke. At that point, the risk of losing viable brain tissue outweigh the risk of bleeding. per the tPA, same thing.


So the dissection actually causes thrombosis which results in the stroke? That makes a bit more sense. I thought the ischemic stroke was due to the dissection causing insufficient blood flow distally. I'm guessing a dissection doesn't cause too much vascular insufficiency to cause a stroke?
 
  • Like
Reactions: 1 user
Members don't see this ad :)
tPA is ok for cervical/vertebral dissections and NOT aortic dissections. Look at the CADISS trial published in 2012. They studied this exact same issue and found no difference in the recurrent stroke risk at 3 months using an antiplatelet vs anticoagulation. The caveat to that study is that patients in the randomized arm were enrolled 7 days from their stroke onset, which may miss an early stroke within that time period. If a patient has an early stroke extension from a propagated intraluminal clot despite using antiplatelet therapy then I'd move up to anticoagulation.
 
  • Like
Reactions: 1 user
A cervical arterial dissection results in an intimal tear, which is intensely thrombogenic. Clot forms and propagates, and then can distally embolize resulting in a stroke. That stroke may respond to tPA. There are case reports of dissections treated with tPA in which additional strokes occurred presumably due to thrombus destabilization from the tPA. Damned either way, but the tPA is given to treat the embolic stroke, not the dissection itself.

Treating the dissection with antiplatelet or anticoagulant medications is done with the goal of stabilizing the thrombus adherent to the intimal tear to prevent distal embolization. One can debate the take-home message of CADISS, but antiplatelet management is likely equally effective in most cases to anticoagulation, at least at the population level, particularly in dissections that do not present with stroke.

Dissections can extend distally, and in rare cases can result in pseudoaneurysm formation which could in theory lead to rupture. This is very uncommon. The only time when we typically consider this is in the case of a V4 vert dissection (V4 is the intradural segment). Dissections often stop at the dura, but they can extend beyond it and the vessel has very little stromal support in the intradural segment. Therefore, minimal propogation of the dissection flap in V4 can cause subarachnoid hemorrhage. I have seen this, and it is indeed very bad.
 
  • Like
Reactions: 1 users
Excellent explanations above.
Just to add a few points:
- the main treatment of dissection itself is normalizing BP to avoid further expansion of dissection and to allow the vessel wall to heal on its own. Most dissections will heal between 3 wks to 2-3 months, even the occlusive ones (the false flap closing the lumen completely). Sometimes they can persist longer. Image can be repeated in 3 months.
- use of anti-thrombotic agents is for occasional intramural thrombus formation sometimes leading to embolic strokes. Statistically primary and secondary strokes due to dissection is low although I tend to see not infrequently for some reason. Between ASA, Plavix and Warfarin, not one seems to be superior to the others. As to the mechanism of intramural thrombus formation a few theories exist but the most convincing theory is turbulent flow in the false lumen.
- the only caveat to using anticoagulation instead of antiplatelet, as often done (albeit no proven superiority) w/ vertebral dissections w/ thrombus and stroke, SAH should be ruled out beforehand. As pointed out above, SAH would occur rarely in intracranial dissections. Some people even use heparin drip initially which I am not too enthusiastic to do.
- per updated "guideline," IV tPA is ok to be given for extra-cranial dissections w/ CLASS II-a evidence. Intra-cranial dissection is "neutral." I would NOT give for aortic or intracranial dissections.
- as to pseudo-aneurysm (false lumen wall engorging out), it can rupture as it gets larger with weakening of the outer wall. Thus, some propose pipeline device if symptomatic. I don't use anticoagulation if pseudo-aneurysm is present.
- if occurred without any identifiable precipitating event and/or involves more than one vessel, investigate for FMD or other connective tissue disorder.

Hope this is helpful.
 
So the dissection actually causes thrombosis which results in the stroke? That makes a bit more sense. I thought the ischemic stroke was due to the dissection causing insufficient blood flow distally. I'm guessing a dissection doesn't cause too much vascular insufficiency to cause a stroke?
I remember being confused about the same thing! Thought I was the only one and felt dumb when I asked my attending. Goes to show it is good to ask questions because there is a high chance your peers are confused as well.
 
Top