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.
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.
it's not just our own gestalt
that we're using to make these determinations.
There are actually two established criteria
that help guide the decision to pursue
or not pursue spine imaging.
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.
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 decision
about who does and doesn't get imaging.
A quick caveat,
neither of these guidelines cover patients
who have neurologic deficits.
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.
They are only designed to be implied
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.
So don't do it.
If you're 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.
These rules are only for intact patients.
The NEXUS criteria is very popular
and very easy to remember
'cause it only includes five criteria.
It includes evidence of focal neurologic deficit,
evidence of midline C-Spine tenderness.
So in particular,
when you palpate the C-Spine
in the middle over the spinous processes,
that maneuver elicits tenderness.
Includes altered mental status,
and any evidence of distracting injury
which the study defined as long bone fractures
outside of the axial skeleton.
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.
If your patient says, “No” to all of those questions.
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%.
Now, there’ve been a few different validations studies
which have reached different conclusions.
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.
So we wanna use NEXUS
with a little bit of caution in that patient population.
The problem with NEXUS is the specificity is only 13%.
Meaning, there's a lot of false positives among patients
in whom we apply the NEXUS criteria.
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.
The other thing that's a little bit problematic
is the X in NEXUS stands for x-ray.
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.
We actually use cervical spine CT-scan now
which is a much higher sensitivity study.
So it’s not clear how applicable these criteria are
in our current practice environment.
That leads us to the Canadian C-Spine rules.
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.
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.
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.
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.
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.
They do have to have a normal neurologic exam
and this one is really important to remember.
They can't have any known prior cervical spine disease.
So if they've degenerative pathology,
if they've had to have spine surgery for any reason
that automatically excludes them from these criteria.
You can't apply it in that patient population.
So just keep that in mind.
The Canadian rules are broken down into three steps.
So step one is identification of high risk factors.
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.
So patients over 65 years of age,
we wanna obtain imaging.
Patients who complain of paresthesias in their extremities,
we wanna obtain imaging,
‘cause remember, this is a neurologic symptom.
This is potentially a sign
that the patient has had a spine injury.
And then lastly,
we wanna obtain imaging for significantly dangerous mechanisms.
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.
High speed motor vehicle collisions,
especially those with any kind of rollover or ejection.
And then, also vehicles like bicycles
and all-terrain vehicles
that don't offer the operator as much protection.
Any of these,
you wanna go ahead and obtain C-Spine imaging
because these patients are in a high-risk group.
If your patient doesn't have any high-risk factors,
you can go on and look for low risk factors.
These are sort of like mitigating factors in court.
They are things that if present,
probably mean that your patient is okay.
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.
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.
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.
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.
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.
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.
And if they have significant spasm and pain
that prevents them from doing that,
you do wanna go ahead and obtain imaging.
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.
Comparing the C-Spine and NEXUS rules,
they both have excellent sensitivity.
The Canadian C-Spine sensitivity is 99 to 100%.
The specificity is much higher however for the Canadian rules.
So the Canadian specificity is 40%
whereas I told you NEXUS was only 13.
we don't expect really high sensitivity
from a screening test like this.
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.
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.
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.
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.
Everybody who's had any kind of cervical trauma
is gonna have tenderness in their neck
when you palpate them.
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.
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.
On the down side for the Canadian rules,
they’re much more complicated than NEXUS.
Everybody can memorize NEXUS, its five simple rules,
it’s easy to keep track of.
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.