More on a Diagnostic Strategy for C-Spine Injuries

Podcast 63 set off some expected controversy given my take that plain films are a dead imaging modality for c-spine injuries. I wanted to briefly outline my impression of the existing evidence:

Worst Case Scenario for Sensitivity

Mathen R, Inaba K, et al. (J Trauma 2007;62:1427)

Showed a sensitivity of 45% for plain films.

Prospective study of trauma patients who could not be cleared by NEXUS. Got 3-view plain films and CT. Gold standard was evidence of injury during entire hospitalization.

Post NEXUS Prevalence was ~10%, so probably a mix of moderate and high risk patients.

Best Case Scenario for Sensitivity

Mower WR, Hoffman JR, et al. Use of Plain Radiography to Screen for Cervical Spine Injuries (Ann Emerg Med 2001;38(1):1)

It is a reanalysis of the NEXUS Data (NEJM 2000;343(2):94)

818 Patients with 1496 c-spine injuries

Missed 320 and found 498 of the c-spine injuries in those 818 patients

Of the 320 misses, 237 were deemed inadequate plain films

So 498 out of 581 patients with adequate plain films

So sensitivity of the exam is 85%; We’ll assume a specificity of 100%

If you evaluate the performance by fracture instead of patient, the numbers become worse

I will say in the Mower paper, they tried to exclude SCIWORA patients, but from what I can glean from this paper (J Trauma 2002;53:1-4), these patients had their MRI without CT scans preceding it. CT may have picked up most of these injuries.

Now how can we get away with such a crappy sensitivity

The reason quoted is the NPV is excellent, they state 99.6% NPV. But NPV is a really crappy number, why…

Because as you change the prevalence, the NPV changes.

So now we need to go to a second enormous study…

Let’s look at the Canadian C-Spine Studies (JAMA 2001;286(15):1841 & NEJM 2003;349(26):2510), why? Because their entry criteria are exactly the patients we want to discuss–namely, acute trauma with alert mental status, an injury within the past 48 hours, and in stable condition. The prevalence of c-spine injuries in these patients was ~2% and in the NEXUS trial it was 2.4% So now we have some numbers for a low risk cohort. However, after you get a group of patients who could not be excluded by CCR, the prevalence of the group increases to ~4%. I would argue these patients are now moderate risk. If you pursue plain film strategy in this group, from the best numbers I can gather, you will miss 1 in 100 c-spine injuries and half of these will be clinically significant injuries.

75% of your plain films will be inadequate and require a CT scan

Plain films read as normal but which have loss of lordosis or soft tissue swelling were interpreted as abnormal by NEXUS folks and demand CT scan, this will account for patients going on to CT as well

Finally, patients with persistent midline pain probably deserve a CT prior to d/c in a collar as well

Let’s Put it all Together

The authors of this paper from the journal Medical Physics (Med Physics 2009;36(10):4461) attempted to take all the variables: radiation risk, cancer, missed injuries, etc. and evaluate whether plain films or CT is a better strategy. The results…in all risk levels, CT was the smarter move. This was with factoring in the putative cancer risks.

What about MRI for patients with persistent Midline Tenderness

BF asked about this in the comments

(Ann Emerg Med 2011;58:521)

44% of patients with persistent pain had an MRI abnormality

and (American Surgeon 2010;76(2):157)

3/20 patients who were alert, oriented but with persistent neck pain after negative CT had MRI findings

Of relevance to Oli Flower’s comments from the previous podcast, a whopping 24% of clinically unevaluable patients had injuries found on MRI.

For a delightful review of the literature on this question, see Adventure of the Crooked Man by EMNERD.

Now, on to the podcast…

 

 

 

Play

You finished the 'cast,
Now get CME credit

Already an EMCrit CME Subscriber?
Click Here to Get CME Credit for the Episode


Not a subcriber yet? Why the heck not?
By subscribing, you can...

  • Get CME hours
  • Support the show
  • Write it off on your taxes or get reimbursed by your department

Sign Up Today!

.

Subscribe Now

If you enjoyed this post, you will almost certainly enjoy our others. Subscribe to our email list to keep informed on all of the ED Critical Care goodness.

This Post was by , MD, published 3 years ago. We never spam; we hate spammers! Spammers probably work for the Joint Commission.

Comments

  1. SteveSattler says:

    Scott: Awesome 2 parter, as always.

    My comment concerns a problem I think I see almost every day. The uncooperative drunk who fell down a flight of stairs/crashed his car/got beat up.
    These guys never want to keep on the collar, often end up wearing it like medieval battle gear, or hurting themselves trying to rip it off.

    So how do you play this? How much or little effort do you put into keeping the drunks in a collar? After their CT is negative and they want to crawl up in the fetal position to sleep, do you let them? Is there any literature showing if the intoxicated patient will/will not pith themselves?

    I’m very curious to hear how you and the listeners handle this common problem.

    -Steve

    • Steve,
      excellent question. at this stage of the game, the chance that they have an unstable injury and they remove the collar, and their alcohol has worn off enough that they are moving around, but still drunk enough that they would move their neck despite the insane feeling that instability in that area causes is inordinately small. Not zero, but probably not worth worrying about.

  2. Wow haven’t done a MRI for neck pain in a while maybe we should be paying more attention to people with persistent symptoms. Difficult to weed out the drug seekers sometimes but, in the right setting would appear useful. Wonder if the results change using a 64 slice CT. Last time I sent someone home with a Miami j collar I watched them take it off as they went out the door!

    • We would find it impossible to get an MRI at most times of the day. So I guess we can just tell the patients the deal and let them decide for themselves whether to heed our words.

  3. Tim LaBelle says:

    Scott
    A question regarding your two podcasts on c-spine injuries . Would degenerative changes on plain films be deemed abnormal and therefore thrown out ? Many patients have early DDD on plain films . Did NEXUS discard these as abnormal or are you unsure. I am Canadian trained and have practiced in both the US and Canada . I blend Nexus and CCS as you do but rarely do CT . Hoffman would argue( if your approach were correct ) what happened to all the broken necks we missed before CT scans were around . I remember doing tomograms on some of these people where our index of suspicion was high because we had nothing else.
    Thanks in advance
    Tim

  4. Salman Ali says:

    I thought sharing an “interesting” C-spine case that I saw two yrs ago might add to your valuable pod casts on the same topic;

    A big, muscular, 39 year old guy, A-grade rugby player (yes, in Australia), was tackled 5 minutes before final whistle. He described it a “usual” tackle, nothing too special. Got up, finished the game, had a bit of chit chat with his mates, walked to his car and sat in passenger seat. His wife drove the car for about 5 minutes when he felt pain in neck for the first time. Pain was at upper neck on the back, more central. It got worse over next 5-7 minutes while they still hadn’t reached their home. Wife changed route and brought him to ED. Cervical collar applied at the triage and he was taken to acute care bed.

    On exam, he met all low risk criteria for NEXUS, although after multiple attempts, upper c. spine palpation could elicit only equivocal response (“umm…a little” was his closest response to admitting mid line tenderness on one attempt – And no, I wasn’t being too gentle on him). More than one CCR low risk crieteria were present, but he was adamant about his constant pain at back of upper neck.

    Sent him to CT. Had two fractures of C1, one on each side of median AAJ. Lucky, after surgery, he went home without any neurological deficits.

    Take home message: Never under estimate patient’s complaints.

    Cheers
    Salman

  5. Daniel Del Vecchio says:

    What do you recommend for rural hospital that wodn’t have accesss to ct?

    • plain films
      if perfect and negative
      range neck
      continued pain, can’t range, or crappy plain films–d/c in collar and f/u for CT scan at academic center

  6. Dr. Weingart,

    My question involves a patient I saw recently. The patient was a toddler who initially presented as a trauma activation after being involved in an MVC. Restrained in car seat. Initial CT cervical spine was read as negative. Pt was hospitalized for several days and reportedly did well without a c-collar. Reported to have some limited motion at first, but mom later reports that the patient was dancing and playing almost back to normal after discharge. However the toddler would report neck pain occasionally. 2 weeks later is when I saw the patient when they returned back to the ED because mom reports the child was refusing to walk and not moving her head. CT cervical spine at this time showed bilateral facet dislocation and severe anterolisthesis at C5 with severe cord compression. Unsure of patient prognosis as the toddler was transferred to another facility with a pediatric neurosurgeon to address the issue. How could this have been avoided? How can you reliably assess a pediatric cervical spine after removing collar, especially since patient was dancing after discharge. When would you flex-ex a child and when would you feel comfortable saying it’s a cervical muscle strain?

    Thank you

    • Greg-That sounds like a horrible case. I only talk about what I know and I know jack about pediatric emergency med. Clearing an infant scares the hell out of me. Any listeners able to comment?

  7. Andyb says:

    I must really be misunderstanding something basic. In Scott’s podcast he talks about using nexus and if midline is tender then go to Canadian when u jump in and rotate pt 45 degree. But This does not make sense to me bc Canadian uses absence of midline tenderness as a low risk criteria if which the answer is “no” then we should X-ray.
    So this Is different than Scott’s decision tree where he says if there is midline tenderness then we should rotate 45 either direction. And then Scott says if they still have tenderness after cr then they need to be rotated again? That seems circular logic?as it is the rotation is clearing them ?

    • Andy, you lost me. In Canadian, if there midline tenderness AND there is at least 1 low risk and no high risk, then you can have patient rotate. If they can’t rotate you get imaging. Then you must recheck persistent moderate tenderness and again if they can rotate. The thought is initially, the patient would have been splinting or uncooperative, but then by the time films or ct has come back negative the patient will rotate (this is allowed to be painful, they just need to do it. I personally would not clear a patient who can’t rotate regardless of whether a clin decision rule was used or we went straight to imaging.

      • andyb says:

        Scott,
        I was a little confused as in your podcast you state that you can not clear someone WITH a negative ct scan if when they return from CT and they still have “significant” midline tenderness. You stated you would still leave them in a collar and follow up with Neurosurgery or MRI. Therefore to me it just does not seem to make intuitive sense that a patient who has one low risk criteria (fender bender, sitting in ER, walked after accident), yet moderate midline tenderness and can rotate 45 degree with pain can be cleared WITHOUT imaging. Seems that we would be at risk for missing a bony not a ligamentous injury.

        Scott I must be misunderstanding something , thanks for trying to clarify this.

        • There are 2 differences in those groups. In the Canadian study, these were already lower risk patients to be included, they excluded trauma room patients. Then you go through further risk strat with the rule itself. Then the idea is that a fully alert patient with an injury will stop themselves before causing damage when rotating with a fracture or ligament tear.

          The clearing after xrays or CT, asks about significant midline tenderness. I would argue that even with canadian, if a distracted patient yelps when I push on one of their vertebra, they are not clinically clearable.

          Now a corollary question is if the patient has midline tenderness before imaging, how are we ever going to clear them even with imaging. The answer is most patients without injury have their midline tenderness become paravertebral by the time their imaging is done.

  8. Anand Senthi says:

    Hey Scott,
    Re the point you make above about the cohort of patients who can’t be excluded with CCR having a risk of 4% which is too high for plain films:
    - this assumes you treat this group homogeneously. Of course in practice amongst that group you may have a young guy whose has no neck tenderness and has been walking around fine but his mechanism was high risk so you couldn’t clear by CCR v’s the elderly chap with a serious mechanism and really severe tenderness whose not walked since accident. So first guy might be 1% risk and fine for plain films while 2nd guy might be 10% risk and clearly must have CT.
    So I agree 4% might be too high for plain films but surely as clinicians we can risk stratify beyond this average risk of the cohort?

    • Absolutely; that is the natures of a Bayesian approach, but not a decision rule at that point so each clinician must make their own choice. I can only give the grouped numbers, the doc on the spot must go from there.

  9. Andrew Jan says:

    Hi Scott,

    what about alert patient who is well, alert, no neuro signs from a seemingly low risk mechanism but still fails NEXUS and CCR where you not only get 3 adequate plain films but also do obliques and flexion / extension films. ( all of which you deem adequate and even sit them up carefully for these films for better quality films). Furthermore get a radiologist to double check the films and obviously any hint including loss of lordosis – get a CT. Surely for either those that can’t get CT’s ( remote) or the patient wishes not to have CT this would markedly reduce our number of missing significant injuries of 1/200? However I can’t find any data on this extended plain film method!

Trackbacks

  1. [...] tanto da indurre lo stesso autore di Emcrit a pubblicare un intero podcast di chiarimento why should we kill off plain films cspine.nel quale passo passo obietta alle critiche dei suoi detrattori fondate sostanzialmente su uno [...]

  2. […] Emcrit podcasts (Part 1, Part 2 and a Wee) on this topic are superb but this chat opens up a whole new can of […]

Speak Your Mind (Along with your name, job, and affiliation)