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Case 24 - Anterior Arch C1 Fracture

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With our craniovertebral junction injuries,

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we really should look at the MRI scan to look for

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the integrity of the ligamentous complex.

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This was an individual who had a fracture

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of the anterior arch of C1.

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And you can see the two bone fragments that are displaced

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from one another at the anterior arch of C1.

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On the scans, we generally focus on the STIR imaging.

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The STIR imaging is the one with obviously the fat suppression.

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It's particularly nice for demonstrating ligamentous

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injury at all parts of the spinal column.

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In this case,

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what we are able to see is that the patient has high

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signal intensity, which is behind the longus colli,

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longus capitis muscle complex,

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which is seen here as this darker signal intensity.

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Now, on the sagittal scan,

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it's sometimes difficult to distinguish between the

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anterior longitudinal ligament, which is seen here,

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and the adjacent musculature,

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which is also dark on a T2-weighted scan.

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So we'll look at the axial scan to better evaluate that.

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In this case, as we look at the anterior longitudinal ligament,

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we see that there is a gap there at the location

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where the fracture has occurred.

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The next thing to look for is the extension of the posterior

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longitudinal ligament from the lower cervical spine

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superiorly onto the tectorial membrane,

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communicating with the back of the clivus.

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So here's our clivus,

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and that actually looks like it is intact.

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Be careful that you're in the midline.

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As you go off midline,

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you will see that the posterior longitudinal ligament

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and tectorial membrane becomes out of plane.

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So if we follow this off to one side,

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we see dark signal intensity of the posterior longitudinal

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ligament to the tectorial membrane.

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And then as we go on the contralateral side,

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you see a discontinuity in that ligament.

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And that would suggest that there is indeed rupture

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of the tectorial membrane just to the, in this case,

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to the right or left of midline.

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The other ligament that we want to look for is a small black

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ligament that attaches from the odontoid process

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to the under surface of the clivus.

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And it's sort of a vertically oriented apical ligament.

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And in this case, once again,

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we see that there is discontinuity of the

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apical ligament on the sagittal image,

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we're not seeing that little dark line that connects

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the inferior clivus to the top of the

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odontoid process, and instead we have bright signal intensity.

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So this is not compromising the spinal cord.

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We don't see a large epidural hematoma,

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but we do see all these findings on the sagittal scan.

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Let's bring up the axial T2-weighted scan.

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And here we have our longus colli musculature.

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Here we have the clivus,

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and we're going to continue inferiorly.

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And we note that this bright signal intensity

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is not in the retropharyngeal space.

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The bright signal intensity is behind the musculature and

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therefore in the prevertebral space where you should

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not see edema, and this is secondary to the trauma.

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So here is this bright signal intensity. Here's

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the longus musculature.

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And here is, what we're seeing here is this prevertebral

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high signal intensity behind the muscle right here.

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Now we're looking at the ligamentous complex,

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which is the anterior longitudinal ligament,

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which runs anteriorly here.

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And this is where we see that discontinuity right here,

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with the bright signal intensity extending right to

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the portion of the odontoid process, right here.

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Looking at the posterior longitudinal

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ligament, behind on the axial scans,

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we see the appearance here of the ligament off midline,

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but on the right side, it's actually bright and

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signal intensity. So on the axial scans,

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what we see is the discontinuity on the right side of that

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tectorial membrane junction with the posterior longitudinal

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ligament seen on the sagittal scan and

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then reproduced on the axial scan.

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So we have ligamentous disruption both in the anterior

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longitudinal ligament as well as the tectorial membrane,

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as well as the apical ligament associated

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with this anterior arch of C1 fracture.

Report

Faculty

David M Yousem, MD, MBA

Professor of Radiology, Vice Chairman and Associate Dean

Johns Hopkins University

Tags

Neuroradiology

Head and Neck

Emergency

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