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The EMCrit Blog & Podcast will help make you a master resuscitationist.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.
Now, on to the podcast…
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Hi, my name is Scott Weingart. 
{ 11 comments… read them below or add one }
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.
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.
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
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
Wow, great and scary case!
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
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?