Tag Archives: vertebral artery

Who Is At Risk For Blunt Cerebrovascular Injury?

Yesterday, I wrote about proper screening for blunt cerebrovascular injury (BCVI). But, as you know, it’s important to screen only when there is a significant risk of the injury being present. Screening using the shotgun approach (screen everyone for everything) yields enough false positive results to present potential danger to your patient.

A variety of authors on this topic have promoted a number of high risk criteria to trigger a screening test. Most make sense, and are related to the anatomy of the vessels in question. The carotid arteries are relatively unprotected, although a bit deep, as they course up the neck. Thus, it is possible to damage them when they suffer a direct and significantly hard blow. Once they enter the skull, they are better protected. However, fractures through key areas of the skull base and face can injure the vessels, even in these protected locations.

The vertebral arteries are deep and relatively protected as they course through the vertebral foramina. However, if the vertebrae are fractured or subluxed, vessel injury can occur.

Finally, and as always, the physical exam is important. If there are unexpected neurologic changes that can’t be explained by other injuries, or there are indications of deep vascular injury, BCVI needs to be considered.

Here is my list of indications to screen for BCVI:

  • Neurologic abnormality not explained by diagnosed injury
    †
  • Arterial epistaxis
    †
  • Seat belt sign on neck
    †
  • GCS < 8
    † (this is the most commonly forgotten one)
  • Petrous bone fracture
    †
  • C‐spine fracture (C1‐C3) or subluxation at any level
    †
  • Fracture through foramen transversum
    †
  • LeFort II or III fractures

Bottom line: Be on the lookout for any of the criteria listed above in your trauma patient. If you find one during your initial evaluation, be sure to order a CT angiogram of the neck. And keep an eye out while scanning the head and cervical spine. If any of the other radiographic indications become apparent, add on the CT angiogram at that point.

What’s The Best Test For Blunt Cerebrovascular Injury?

Blunt injury to the carotids or vertebrals (BCVI) is a little more common than originally thought, affecting about 1% of blunt trauma patients. We have many tools available to help us diagnose the problem: duplex ultrasound, CT angiography (CTA), MR angiography (MRA), and even good old conventional 4 vessel angiography

But which one is “best?” This is a tough question, because there is always some interplay between clinical accuracy and cost. The surgical group at the Medical College of Wisconsin – Milwaukee did a nice job teasing some answers from existing literature on the topic. The authors tried to take a comprehensive look at costs, including money spent to prevent stroke, the cost of complications of therapy, and the overall cost to society if the patient suffers a stroke.

Here are the factoids:

  • For patients at risk for BCVI, the stroke rate is 11% without screening, 6% with duplex ultrasound screening, 4% with MRA, and 1% with either CTA or conventional angiography
  • From a societal standpoint (includes the lifetime costs of stroke for the patient), CTA is the most cost effective at $3,727 per patient
  • From the hospital standpoint (does not include lifetime cost), no screening is the most cost effective, but has the highest stroke rate (11%)
  • CTA prevents the most strokes, and costs about $10,000 per patient while decreasing societal costs by about $32,000 per patient screened

Bottom line: The “best” test for patients at risk for blunt cerebrovascular injury is the CT angiogram. It minimzes the stroke rate, and provides information on all four vessels supplying the brain, which is probably why the duplex ultrasound has a higher miss rate (can’t see the vertebrals or into the skull). But how do you decide who is at risk for this problem. Tune in tomorrow!

Reference: Screening for Blunt Cerebrovascular Injuries is Cost-Effective. J Trauma 70(5):1051-1057, 2011.

Practical Tip: Penetrating Injury To The Vertebral Artery

This is an uncommon injury. But when encountered it can cause the trauma professional (and the patient) some major headaches. The majority of the vertebral artery injuries you are likely to encounter are caused by blunt trauma. They are generally diagnosed using CT angiography, and the treatment usually consists of low dose anti-platelet agents like aspirin. Occasionally, coiling or stenting using interventional radiology is needed.

But penetrating trauma is a totally different animal. Gunshot is the most common mechanism, because of the small windows available to access the artery within the vertebral canal using a knife. See the course of the artery in the picture below:

Unfortunately, this bony cage also makes it difficult to surgically approach the artery, especially if the field is continually filling with blood.

The techniques for dealing with this injury according to the doctor books are:

  • Send the patient to interventional radiology. Cutting off flow using coils is the preferred technique. Gelfoam and other products are not used because of the concern for distal embolization (to the brain). Stenting may be a consideration for blunt trauma, but not for penetrating.
  • Or, obtain proximal control by ligating the vertebral artery as it takes off from the subclavian. Hmm, this requires either a separate incision, or a supraclavicular extension of your neck incision. It takes time and is not as easy as it sounds.

Generally, the trauma surgeon stumbles upon this injury while doing a trauma neck exploration. Bleeding can be pesky, and may serve to obscure the field. My preferred method of control is:

  • Jam a wad of bone wax into the vertebral canal right where the bleeding is coming from.
  • Then jam another wad into the canal in the space below it. Proximal control!
  • Jam one final wad into the space above, if accessible. Distal control!

End of problem. Then do a thorough evaluation for all other injuries and address them. Feel free to share any additional tips that you may have!