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Welcome back to the tasty morsels of critical care podcast.
Today we look at blunt cerebrovascular injury or BCVI. I added this to my list to cover for unclear reasons as when i looked back at my notes i had about 8 bullet points and a couple of referenced articles. So this will be shorter than usual I suspect.
Effectively this refers to injuries to the carotids and vertebral arteries in the context of trauma. The pathology here is typically a pinch, twist or stretch of the vessel leading to an intimal tear in the vessel. The exposed endothelium then is a nidus for thrombus formation. The main downstream consequence is stroke and it’s a real shame to have a successful haemostatic and surgical resus of a major trauma patient only to have them suffer a life changing stroke 3 days into their hospital stay.
They’re also pretty tricksy injuries as there are rarely obvious clinical signs to indicate their presence until they you find the dense hemiplegia, so this is one of those things were the term “index of suspicion” comes into play. It is especially important seeing as we have now effectively outsourced all diagnosis to the radiologists and these injuries are not picked up on the typical trauma pan scan that we so love.
Given that I described the pathology of the injury as pinching, twisting and stretching we can probably get a sense of the mechanism of injury associated with these injuries. Top of the list here are c-spine injuries – if the neck has moved enough to break it you should think about the delicate blood vessels beside the c-spine. This is particularly pertinent to the vertebrals whose course, evolution in her wisdom, placed inside the tiny little vertebral foramen transversarium of the c spine itself. To make life more difficult for the poor little vertebrals they have to navigate a few 90 degree turns to get between C1 and the skull to get into the foramen magnum. This is reflected in the higher incidence of BCVI in high spine injuries.
Obvious other associations are with severity of TBI and complex facial fractures (remember the carotid has to navigate its way past these).
You might get some pointers to diagnosis from your clinical exam. Horner’s syndrome would be a classic (disruption to sympathetic neurons in the carotid) but if you’re diagnosing a Horner’s syndrome in your primary survey then you’re either over achieving or doing it wrong or possibly both. They may have stroke features on arrival which would be an obvious trigger for imaging. A bruit is also listed as a sign of injury but I think that’s a sign for better clinicians than you or I.
Most of the time you will have an injured patient without specific symptoms of BCVI. Who do we pursue further imaging on given that I’ve already noted the initial trauma pan scan will often not pick up this?
Enter stage left the geographically titled criteria each named after the academic centre that developed it. Denver, Memphis and Boston have all contributed a published criteria. The Denver criteria appear to be the most commonly used and referenced. I think listing the individual components is probably beyond the scope of the post but I’d emphasise the main headlines
- c-spine injuries
- facial fractures
- complex base of skull
- severe TBIs
- hanging
Once you’ve decided the patient needs imaging then you should be reaching for our trusty friend the CT scanner. in this case a well done CT angiogram of the neck vessels extending into the intracranial vessels. It is not (unsurprisingly) a perfect test but it is a very good test and certainly where you should start. If you do find a BCVI you may even have the joy of seeing it classified I to V according to the wonderfully named Biffl classification system. It covers things like intimal tears and degrees of narrowing and occlusion.
once you’ve found a BCVI it’s unclear who your go to specialist might be and I have seen vascular, neurosurgery and stroke all give opinions on treatment. Overall risk of stroke in BCVI is ~8% but changes significantly depending on grade with higher grades having higher stroke risk.
For the vast majority of patients your treatment options come down to heparin vs aspirin. There does not appear to be a clear proven superiority of one strategy over the other. Some form of antithrombotic does, in observational data, seem to reduce stroke rate and is probably worth doing. Aspirin is generally easier delivered and seems to be the most common choice in our region. Many of the injuries would actually be amenable to surgical repair but the vast majority are surgically inaccessible hence the antithrombotic treatment as next best thing.
The decision to give something that makes clotting more difficult in a patient who is either still bleeding or at risk of major bleeding is not an easy one. Hence there is typically a day or two of hand wringing amongst several specialties till we are all comfortable giving it. Observational work suggests that we’re likely a little overcautious on this in a similar way to our reluctance to commence VTE prophylaxis in TBI.
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