C-Spine Imaging

00:01 So there's a large number of patients who arrive in cervical collars who can be cleared on the basis of their history and physical exam alone.

00:10 Meaning, that we can identify reassuring findings in their history and in their physical exam that allow us to feel confident that they don't actually need imaging that we know that they do not have significant spinal injury just based on our assessment.

00:26 Now fortunately, it's not just our own gestalt that we're using to make these determinations.

00:30 There are actually two established criteria that help guide the decision to pursue or not pursue spine imaging.

00:38 And those are the NEXUS criteria and the Canadian C-Spine Rules which I'm gonna talk about in some detail 'cause they are very helpful for emergency physicians.

00:47 We should really always be using these evidence-based validated decision rules to stratify our patients risks for C-Spine injury, so that we can make intelligent decisions about who does and doesn't get imaging.

01:01 A quick caveat, neither of these guidelines cover patients who have neurologic deficits.

01:07 So if your patient has a depressed GCS, if they're complaining of neurologic symptoms or they have neurologic signs on your physical exam, these criteria do not apply.

01:19 They are only designed to be applied to a neurologically intact patients and if you try to use them in settings where patients actually have signs or symptoms of injury, you're gonna be applying them in a much higher risk group than that in which they were intended.

01:35 So don't do it.

01:36 If your patient has a depressed GCS or if they have neurologic findings on their exam or neurologic complaints in their history, go ahead and get imaging.

01:45 These rules are only for intact patients.

01:49 The NEXUS criteria is very popular and very easy to remember 'cause it only includes five criteria.

01:55 It includes evidence of focal neurologic deficit, evidence of midline C-Spine tenderness.

02:01 So in particular, when you palpate the C-Spine in the middle over the spinous processes, that maneuver elicits tenderness.

02:09 Includes altered mental status, intoxication, and any evidence of distracting injury which the study defined as long bone fractures outside of the axial skeleton.

02:20 So things like femur fractures, femoral fractures, etcetera with the idea being that this might be sufficiently painful that they prevent the patient from recognizing the pain that's in their neck with examination.

02:34 If your patient says, “No” to all of those questions.

02:38 So they have a normal neurologic exam, they’re not intoxicated, they’re not altered, they don't have any distracting injuries, etcetera, the sensitivity of those findings for absence of C-spine injury is between 90 and a 100%.

02:55 Now, there’ve been a few different validations studies which have reached different conclusions.

02:59 The initial validation study showed a sensitivity of greater than 99.5% but there's actually some evidence that's come out a little bit later to suggest that the sensitivity might be lower, particularly in elderly patients.

03:12 So we wanna use NEXUS with a little bit of caution in that patient population.

03:18 The problem with NEXUS is the specificity is only 13%.

03:22 Meaning, there's a lot of false positives among patients in whom we apply the NEXUS criteria.

03:28 So we really can't use NEXUS to avoid imaging in that many patients, because there's such a large number of false positives that we end up imaging the vast majority of patients according to these criteria.

03:44 The other thing that's a little bit problematic is the X in NEXUS stands for x-ray.

03:49 So this study came out in the late 90's or early 2000’s and it was at a time when x-ray was the initial imaging modality for C-spine trauma, that's no longer the case.

04:01 We actually use cervical spine CT-scan now which is a much higher sensitivity study.

04:07 So it’s not clear how applicable these criteria are in our current practice environment.

04:13 That leads us to the Canadian C-Spine rules.

04:16 So the Canadian rules are helpful because they’re a little bit more permissive than NEXUS as far as the patients that you can apply them on.

04:25 Your GCS has to be 15 but it’s actually okay for you to be intoxicated under the Canadian C-Spine rules if you're alert, cooperative, and appropriate.

04:35 Now, we all know that intoxication is a major risk factor for trauma, so it's not uncommon that we see patients who are mildly intoxicated and we previously had to image all those patients under NEXUS.

04:47 Now, under the Canadian rules, again, provided they're alert and their behavior is reasonable, we can consider using the Canadian C-Spine rules to possibly exclude the need for imaging.

05:01 Patients have to be hemodynamically stable, so they have to have stable vital signs, we don't wanna be applying this rules on patients with multi trauma who are unstable.

05:09 They do have to have a normal neurologic exam and this one is really important to remember.

05:14 They can't have any known prior cervical spine disease.

05:18 So if they've degenerative pathology, disc herniations, if they've had to have spine surgery for any reason that automatically excludes them from these criteria.

05:28 You can't apply it in that patient population.

05:30 So just keep that in mind.

05:32 The Canadian rules are broken down into three steps.

05:36 So step one is identification of high risk factors.

05:40 The idea being that if your patient has any of these things, they are at a higher risk for having a spine injury and you want to go ahead and obtain imaging.

05:49 So patients over 65 years of age, we wanna obtain imaging.

05:54 Patients who complain of paresthesias in their extremities, we wanna obtain imaging, ‘cause remember, this is a neurologic symptom.

06:01 This is potentially a sign that the patient has had a spine injury.

06:05 And then lastly, we wanna obtain imaging for significantly dangerous mechanisms.

06:10 So this include high falls, axial loading injuries, such as those that happen with diving when you strike your head on the bottom of the pool.

06:19 High speed motor vehicle collisions, especially those with any kind of rollover or ejection.

06:24 And then, also vehicles like bicycles and all-terrain vehicles that don't offer the operator as much protection.

06:31 Any of these, you wanna go ahead and obtain C-Spine imaging because these patients are in a high-risk group.

06:40 If your patient doesn't have any high-risk factors, you can go on and look for low risk factors.

06:45 These are sort of like mitigating factors in court.

06:48 They are things that if present, probably mean that your patient is okay.

06:53 So they include things like, are they sitting up in the Emergency Department? Were they walking around at the scene or have they been walking around since they've been in the emergency suite? Do they have delay onset neck pain? So they thought they were fine at first and then they woke up the next morning with neck pain? Odds are that's not a fracture.

07:12 Do they have absence of midline tenderness? So if you palpate down all of their bones, are they completely non-tender? That's probably a good sign that their neck’s not broken.

07:21 And then lastly, were they in a simple rear-end MVC? It's actually very, very difficult to cause spine injury from a simple rear-end collision, so the likelihood is pretty low if that was your patient's mechanism that they’re gonna actually have spine trauma.

07:38 So if your patient has no high-risk factors and they do have any one of these five low risk factors, you can then move on to step three and say, "Great. My patient has a pretty low risk of injury.

07:50 So what I'm gonna do now is ask them to actively rotate their neck 45 degrees to each side.” If they're able to do that, you don't need to image them, you're done with the Canadian C-Spine rules at that point.

08:05 Now, it’s important to remember, this is the patient actively rotating their neck, so you're not gonna crank their neck around yourself, you're gonna let them do it.

08:13 And if they have significant spasm and pain that prevents them from doing that, you do wanna go ahead and obtain imaging.

08:21 Again, we're only gonna complete the step if they have no high-risk factors and they have at least one low risk factor, so we're gonna use their history and physical exam to help identify patients who are already at low risk before we go manipulating the neck.

08:37 Comparing the C-Spine and NEXUS rules, they both have excellent sensitivity.

08:43 The Canadian C-Spine sensitivity is 99 to 100%.

08:48 The specificity is much higher however for the Canadian rules.

08:52 So the Canadian specificity is 40% whereas I told you NEXUS was only 13.

08:58 Now again, we don't expect really high specificity from a screening test like this.

09:04 The goal of a screening test is to identify all the patients who have the disease, so that's gonna necessitate that we cast a wide net and include a large number of false positives.

09:16 However, 40% gives us a little bit more leeway to potentially avoid imaging on a larger group of patients compared to only 13% which is the case for NEXUS.

09:29 On the pro side, the Canadian rules allow us to clear a large number of patients who can't be cleared under NEXUS and in particular, the two groups that we can clear with the Canadian rules include mildly intoxicated patients and patients with neck tenderness.

09:46 And for anybody who's practiced in the emergency setting for a long time, you will know that neck tenderness is the bane of your life.

09:52 Everybody who's had any kind of cervical trauma is gonna have tenderness in their neck when you palpate them.

09:59 In fact, I myself had a motor vehicle collision not too long ago and I was shocked at the amount of pain and tenderness I had from what was a very simple mechanism and I knew that I wasn't seriously injured.

10:11 So this is something that is actually a really big deal, because tenderness is almost universally present in patients with spine trauma and if you can potentially clear somebody even if they are tender, that allows you to avoid imaging in a larger population of low risk patients.

10:30 On the down side for the Canadian rules, they’re much more complicated than NEXUS.

10:34 Everybody can memorize NEXUS, its five simple rules, it’s easy to keep track of.

10:39 Whereas for the Canadian rules, you probably need to go to the computer and look these up each time you apply them, because the exclusion criteria are more extensive and the algorithm itself is more complex.