Does NEXUS work in the elderly?

There aren’t a lot of studies specifically examining whether the NEXUS criteria are reliable (e.g. don’t miss important C-spine injuries) in the elderly.

Most of the big studies that derived and validated the NEXUS rule enrolled patients of all ages, so they do include this population. But their average age was much younger (20s-40s in most cases), so if you pick out the older subset, you’ll knock down the n from thousands down to much less. (That would be equally true if you asked about validity for any other small age range, of course.)

So how many older patients has NEXUS been applied to? It’s hard to know. Neither the original NEXUS derivation nor the validation give full age breakdowns, although their range does go up past 100, so there were some patients in that older group. It’s a similar story in a retrospective chart application using NEXUS, and in a study that compared NEXUS with the Canadian C-spine rule. These are all studies with thousands enrolled, though, so even in the subsets the numbers should have some weight.

Domeier 2005 studied a modified NEXUS for prehospital use, and they do give an age breakdown; eyeballing the chart it looks like about 1900 total enrolled age 75+. They found an overall sensitivity that was a little lower than in the other studies, about 92%, and it’s true that a fair number of their injuries were in the older cohort, but none of the missed injuries mattered (no clinical sequelae).

Now, Goode 2014 was just released and seems to be one of the only studies specifically addressing this. They concluded that NEXUS wasn’t very sensitive with age >65, with sensitivity only 65.6%. However, the sensitivity below 65 was only 84.2%, which is dramatically less than in the other studies, so they’re clearly doing something different; if we trust these numbers we shouldn’t be using NEXUS for anybody. Mainly, the difference seems due to higher a high-risk population enrolled; they only looked at patients with

… associated injuries from high-energy mechanisms (e.g., pelvic/long bone fractures), ejection from a vehicle, death in same compartment vehicle, fall from greater than 20 feet, vehicle speed greater than 40 mph, major vehicle deformity/significant intrusion, and pedestrian struck with speed greater than 5 to 20 mph.

In other words, big-sick trauma activations, not the “all blunt trauma” population used in the other studies. This is reflected in the higher rate of C-spine fracture in both groups: 7.4% in the young and 12.8% in the old, which is far higher than the ~2% rate of fracture in most other studies. Since it’s unlikely that these types of patients are getting clinically cleared anyway — no matter what, they’re getting a collar from most EMS crews and a CT scan from most EDs — I’m not sure how useful this data is. NEXUS is for small injuries with patients that look okay, not multi-system trauma codes.

So do older patients qualify for NEXUS? The data is not as robust in defense of this practice as for younger patients, certainly. But it does support its use; none of the major NEXUS studies put a cap on age and they all included at least some age >75 or >85 or whatever.

If you are very worried it may be reasonable to insist upon a specific study validating this age range, with enough power to focus on that specific population, but I’m not sure why you should be so worried. Although they may be at higher risk for fracture, that’s not the issue; the issue is whether the NEXUS criteria can detect those fractures, and I don’t think there’s any good reason to say that all old patients can’t reliably report pain or neuro deficits. Obviously selected patients, for instance with cognitive impairment, peripheral neuropathies, or other conditions may present obstacles, but hopefully your clinical judgment would already tell you that you may not be able to clinically clear those people anyway. NEXUS specifically has caveats to skip patients patients who can’t reliably report their symptoms — intoxicated, distracting injury, AMS — and if there’s something present which isn’t on that list but is still confounding things, you probably shouldn’t clear them. When it comes to corner cases, use the principles, not the letter of the law.

If anybody is really worried about this we can perhaps write to Hoffman or some of the other authors and ask if they have the age breakdowns for their big studies; that way we’d know exactly how many older folks have actually been studied.

Or just use the Canadian C-spine rule, which includes age >65 as an exclusion anyway. (Yep, it’s been validated for prehospital use as well.)

The Legend of the Unstable Spine

So the AANS/CNS released an update to their 2003 guidelines for acute spinal care (Theodore 2013), and this is in the introduction to the prehospital chapter:

Pathologic motion of the injured cervical spine may create or exacerbate cervical spinal cord or cervical nerve root injury.9-11,16,51,52

Although immobilization of an unstable cervical spinal injury makes good sense and Class III medical evidence reports exist of neurological worsening with failure of adequate spinal immobilization, there have been no randomized trials or case-control studies that address the impact of spinal immobilization on clinical outcomes after cervical spinal column injury.3,4,6,11,12,15,16,27,31,32,53

Actually, if you read through enough papers on spinal immobilization, pretty much every introduction reads this same way. First they say “spinal fractures suck, this is their prevalence”; then they say, “not immobilizing these patients can increase morbidity and disability, which is catastrophic”; then they say, “there’s actually no evidence for immobilization, but still.

It’s the third part that chafes my nuts, because “the exception proves the rule” — by acknowledging the inadequacy of evidence for our immobilization techniques, it seems to confirm that the other stuff is well-supported. In particular, it seems clear that “pathologic motion may create or exacerbate” cord injury. Just look at all those citations!

But in reality, it’s all just hand-waving. In philosophy, there’s a school called “coherentism,” which essentially states that a system of beliefs is “true” if everything you believe mutually agrees — regardless of whether the lot of it has any connection to reality. This is pretty much what we’re dealing with, because if you start looking through those citations — and this is true for every one of those spine papers with carbon-copy introductions — you find that there’s no “there” there. Most of the pieces cited (they’re all in the DRL if you want to explore) only support the idea of neurologic deterioration in a single sense: that they also made this same unsupported statement in their introduction. In some cases they mix it up and say it in the conclusion. But either way there’s no actual connection with reality, except in the sense that they cite a bunch of similar papers that made the same unsubstantiated claim in their introduction. Round and round it goes.

The threadbare actual evidence for this consists of examples of neurologic deterioration that happened after hospital arrival, either in the ED, in the OR, on the floor, or in at least one case while moving someone to the x-ray table. These are exclusively case reports or case series, but at least go to show that the concept is not completely fictional. However, there are no examples of this happening prior to hospital arrival, which is presumably what “prehospital” immobilization is meant to address. (There are a few cases of people hurting themselves, walking around for a few hours or days, and then self-presenting because they developed tingling in their arm or something, but that’s not really the catastrophic event we’re trying to prevent and is not an EMS matter either.)

Really the only primary “evidence” of this happening is from two or three very old papers that claim it happens all the time, but as a rule, give no further support or details to back that statement. For instance Geisler 1966:

These 29 comprise those patients who at first had little or no spinal cord involvement although they had suffered spinal column injury of great severity. The subsequent development of serious spinal cord involvement is confirmed by clinical observation or circumstantial evidence. The evidence for this statement derives in each case from the recorded witness of a reliable observer or from the account given by a credible patient who is able to report activities such as walking or definite use of the hands following spinal injury, and who subsequently had lost the ability to use these members owing to developing paralysis. The paralysis occurred in each case as a consequence of failure to recognize the injury to the spinal column and to protect the patient from the consequences of his unstable spine. He may thus have essayed to walk, or even sit up for a drink. It may have occurred when the patient was being moved from the site of accident to a hospital.

Or the true classic, Toscano 1988, who claimed that a whopping 28% of cord-injured patients deteriorated between injury and hospital admission, due entirely to inadequate immobilization. But he describes none of these patients in detail, the actual published paper is incredibly terse, and for further information you’d have to read his med school thesis, which only exists on paper in the University of Melbourne library. Good luck with that.

Anecdotally, of course, everyone in EMS has heard about the patient who moved wrong and was forever paralyzed. But in reality, if this happened, it would be publishable, because that person doesn’t exist anywhere in the literature. (Of course, maybe if that happened, the medics involved would just button their lips and never speak of it, so you could make an argument for reporting bias.)