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Dural AVF vs. Normal Variation

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This is the quandary that we sometimes have

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with evaluation for patients who have vascular

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malformations of the spinal canal.

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This is a patient who had

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a thoracic myelopathy.

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As we scroll the images on T2-weighted scans,

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we see what appears to be prominent vessels on

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the surface of the spinal cord, which are

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selective in the lower thoracic region.

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We don't see them going superiorly

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above the T6 level.

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This is present both on the STIR image, as well

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as on the traditional spin echo T2-weighted scan.

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Lots of prominent vessels in the intradural

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extramedullary space.

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Well, it is said that patients who have vascular

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malformations, like a dural AV fistula,

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if they're symptomatic,

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they almost always will have abnormal

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signal intensity in the spinal cord.

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In this case,

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both on the STIR and the T2-weighted scan,

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the spinal cord signal is normal.

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So what will we do?

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Is this a vascular malformation that just

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hasn't gotten to the level of venous

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congestion that the cord is bright?

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Or is this normal variation blood vessels

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on the surface of the spinal cord?

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In this situation,

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we would obtain postgadolinium-enhanced scans

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and in this particular patient,

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that was not performed.

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But the patient did go on to spinal arteriography

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and it was normal.

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So again,

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the adage is that if it is a symptomatic

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spinal dural AV fistula,

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you should see abnormal signal intensity

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within the spinal cord.

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And if you don't see abnormal

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signal in the spinal cord,

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then I would be a little bit more cautious

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about calling it a vascular malformation.

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So again, word to the wise,

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do the postgadolinium-enhanced

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scans. And also, if that is equivocal,

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try your spinal arterioven...

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uh, your spinal angiogram.

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Your dynamic injection of contrast

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for a spinal angiogram.

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So, what's the difference between this case

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and the previous example I demonstrated?

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Here we have a patient that also

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has a thoracic myelopathy.

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The patient is 69 years old.

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And we again see what appear to be a lot of

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prominent squiggles on the surface

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of the spinal cord.

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You'll notice that they are predominantly

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on the posterior aspect,

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although more anteriorly here.

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And there is also associated cord signal abnormality.

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So here is the demonstration of the intradural

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intramedullary cord signal abnormality, in

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associated with prominent vessels in the

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intradural extramedullary location

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that are present on STIR imaging.

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Little squiggles. As well as post contrast imaging

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where we see them as little dots of contrast enhancement

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in the intradural extramedullary compartment.

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So the difference between this case and the

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previous case is that the vascular abnormality that we see,

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or the blood vessels, are extending all the way

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up to the cervical region and down

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to the lower thoracic region.

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It is associated with abnormal cord

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signal abnormality. And in fact,

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on the post gadolinium-enhanced scans,

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we see that there is is kind of a faint

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enhancement of the cord itself.

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This is secondary to that venous congestion

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that I mentioned previously.

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I'm just going to magnify that and compare it

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to the pre gadolinium T1-weighted

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images where, again,

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you see that there is that faint enhancement

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in the conus medullaris.

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So this is a patient who had a dural

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arteriovenous fistula.

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Type 1 spetzler classification,

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associated with abnormal cord

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signal myelopathy, as well as draining

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veins in the intradural extramedullary

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compartment and cord signal abnormality,

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intradural intramedullary. So, again,

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this is a patient that gets referred

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to conventional arteriography,

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at least at my institution.

Report

Description

Faculty

David M Yousem, MD, MBA

Professor of Radiology, Vice Chairman and Associate Dean

Johns Hopkins University

Tags

Vascular Imaging

Vascular

Spine

Neuroradiology

Musculoskeletal (MSK)

MRI

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