Tag Archives: Cervical spine

Is Applying Or Removing That Cervical Collar Dangerous?

Cervical collars are applied to blunt trauma patients all the time. And most of the time, the neck is fine. It’s just those few patients that have fracture or ligamentous injury that really need it. 

I’ve previously written about how good some of the various types of immobilization are at limiting movement (click here). But what happens when you are actually putting them on or taking them off? Could there be dangerous amounts of movement then?

Several orthopaedics departments studied this issue using an electromagnetic motion detector on “fresh, lightly embalmed cadavers” (!) to determine how much movement occurred when applying and removing 1- and 2-piece collars. Specifically, they used an Aspen 2-piece collar, and an Ambu 1-piece. They were able to measure flexion/extension, rotation and lateral bending.

There were no significant differences in rotation (2 degrees) and lateral bending (3 degrees) when applying either collar type or removing them (both about 1 degree). There was a significant difference (of 0.8 degrees) in flexion/extension between the two types (2-piece flexed more). Movement was similarly small and not significantly different in either collar when removing them.

Bottom line: Movement in any plane is less than 3-4 degrees with either a 1-piece or 2-piece collar. This is probably not clinically significant at all. Just look at my related post below, which showed that once your patient is in the rigid collar, they can still flex (8 degrees), rotate (2 degrees) and move laterally (18 degrees) quite a bit! So be careful when using any collar, but don’t worry about doing damage if you use it correctly.

Related post:

Reference: Motion generated in the unstable cervical spine during the application and removal of cervical immobilization collars. J Trauma 72(6):1609-1613, 2012.

Best Of: Flexion / Extension Views of the Cervical Spine

I’ve gotten a number of requests about the use of flexion-extension views of the cervical spine to aid in spine clearance. Here are some answers to common questions about this practice.

Clearance of the cervical spine can often be done using clinical criteria alone (see this video at http://youtu.be/NhjF9kDOcjE). If this is not possible, a combination of radiologic and clinical evaluation is usually carried out. 

In some cases, radiographic studies (usually CT) are normal, but there is pain on clinical exam. Our next step is to send the patient to xray for flexion and extension views. This exam is performed by removing the collar while the patient is sitting, so the thoracic and lumbar spines must be clear before ordering this. The patient then gently flexes and extends the neck to their limits of comfort. Images are then obtained at the limits of flexion and extension. The premise is that a normal, awake patient cannot and will not move their neck beyond their comfort level to the point where they could cause themselves neurologic injury. 

It is very important that you look at the images yourself. The radiologist may review the images and will report that “there is no evidence of subluxation at the limits of flexion and extension.” But the patient may have barely moved their neck!

The question is: how much flexion and extension do you need to have to clear the spine?

The answer is not easy to find, and is buried in literature from the 1980s and 90s. According to the EAST guidelines, the ideal amount is 30 degrees from neutral for both flexion and extension. This is not always achievable in elderly patients, so in those cases you must use your judgment. Talk to the patient to find out if they stopped moving their neck forward or backward due to pain, or because they just can’t move it that far.

Trouble signs to look for are:

  • Subluxation of more that 2mm at any level
  • Angulation of more than 11 degrees

Any abnormality should prompt a spine consult.

If the study is not abnormal but the amount of flexion and/or extension is not adequate, there are two options. First, just leave the collar in place and try again in a week or so and try again. This will allow any soft tissue injuries to get better and may allow a successful repeat study. The alternative is a more costly and less well-tolerated MRI.

Related posts:

References:

  1. EAST Practice Guidelines, Identifying Cervical Spine Injuries Following Trauma – Update (2000).
  2. Defining radiographic criteria for flexion-extension studies of the cervical spine. Robert Knopp et al. Ann Emerg Med. 2001 Jul;38(1):31-5.
Image: C5-6 subluxation with only a slight amount of flexion

Clearing The Cervical Spine With MRI

If you follow the trauma literature, clearance of the cervical spine in obtunded patients is confusing at best. Although there is some literature out there that suggests that a good cervical CT alone is adequate, I’m not a believer. I’ve seen a case where the radiologist called the scan normal and a good spine surgeon called an injury and was right. So I’m reluctant to use CT alone because the skills of radiologists vary widely. I might be able to believe a dedicated neuroradiologist, but you can’t guarantee one will be reading your patient’s images.

So I fall back on the routine of clearing the bones with a CT scan, and the ligaments with something else. That something else could be a clinical exam (not available in the obtunded patient), flexion-extension images under fluoroscopy (makes a lot of people nervous), keeping the patient in a collar for weeks (skin breakdown), or an MRI. The problem is that there is little guidance in the literature regarding how good MRI is or the best way to use it.

A recent paper in the Journal of Trauma retrospectively looked at 512 out of 17,000 patients (!) seen over 5 years at one trauma center who had both CT and MRI of the c-spine. They wanted to determine if MRI was of any value in cervical spine clearance. Only 150 met the inclusion criteria (GCS<13, no obvious neuro deficit, normal CT). Half of the MRIs were normal. Of the abnormal ones, 81% showed a ligamentous or soft tissue injury. None were deemed unstable and no specific management was needed for any of the abnormal scans.

The authors interpreted their data as showing that MRI provided no additional useful information. However, numbers were (very) small, so the likelihood of them seeing someone with an unstable ligamentous injury was low. Could it be that they showed that MRI detected stable injuries well, and that they could essentially remove the collar based on that?

Bottom line: We still don’t know how to use MRI for clearance. My bias (no good data I can find) is that it is good in suggesting ligamentous injury via nearby edema. If this injury involves only one set of ligaments, it is very likely a stable one and the collar can be removed. If it involves several groups of ligaments, that is probably not the case. And how soon do we have to get the MRI after injury? Some have suggested that 72 hours is the ideal window because edema decreases afterwards. Sounds reasonable, but I can’t find a shred of evidence in the literature. For now, I’ll get an MRI within 72 hours and if it is abnormal, pass the buck to my neurosurgical colleagues so they can gnash their teeth, too.

I would be very happy if someone can help me out and point me towards some good literature on this topic!

Reference: The value of cervical magnetic resonance imaging in the evaluation of the obtunded or comatose patient with cervical trauma, no other abnormal neurological findings, and a normal cervical computed tomography. J Trauma 72(3):699-702, 2012.

More on Distracting Injury and Spine Clearance

There is a lot of angst out there among trauma professionals when it comes to clearing the cervical spine and possible distracting injuries. I’ve written about this before, and the most important technique I use is to try to see if the patient is aware of pain in areas distant from the suspected distraction.

A recent prospective study looked at injury patterns and c-spine clearance in over 9,000 trauma patients at a single Level I trauma center. Of those, 101 were evaluable (not intoxicated, no head injury) and actually had a cervical fracture. 96% of them were symptomatic, despite the majority having what would normally be considered a distracting injury (87%). Of the 4 who did not have pain or tenderness on examination of the neck, every one of them had a distraction.

There was a pattern as to which “distracting” injuries were really a distraction. All four of the asymptomatic patients had bruising or tenderness to the upper anterior chest, which diverted their attention away from their neck. Other injuries caused pain in some of these patients, but it was outweighed by the chest wall pain.

Bottom line: Distracting injury is currently defined too liberally, which results in lots of patients getting lots of unneeded cervical spine imaging. Although this study is small, it adds one more piece of information to the c-spine clearance puzzle. I personally will add this to my current practice and clear the cervical spine if:

  • The patient is aware of multiple sources of pain
  • Subjective pain scale overall is less than 6 (otherwise provide better pain control!)
  • There is no pain/tenderness/injury to the upper chest 

Related posts:

Reference: The presence of nonthoracic distracting injuries does not affect the initial clinical examination of the cervical spine in evaluable blunt trauma patients: a prospective observational study. J Trauma 71(3):528-532, 2011.