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Density of Falx/Tentorium

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One of the classic predicaments of residents

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on the emergency department service for

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neuroradiology is assessment of whether the falx

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or the tentorium is showing a subdural hematoma.

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And I must admit that even I, after 30 years of

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doing neuroradiology practice, sometimes scratch

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my head and say, is that just the dense, uh, falx?

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Or is there blood on the falx?

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Fortunately, as you've heard with respect to

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the surgical indications for disease, unless

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it gets 10 millimeters thick or 15 millimeters

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thick, it's really not going to be, uh,

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an issue that the patient requires surgery.

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So here we have a patient.

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On the right-hand side, where you see the posterior

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falx and you're just seeing the leaflets of the

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tentorium, and it seems dense, is there blood

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on the tentorium or on this posterior falx?

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Again, sometimes this is a judgment call.

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You'll look at the anterior falx and see

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whether it too has a similar density.

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You'll look at the leaflets of the tentorium along the

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transverse sinus and see whether it has

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a similar density, and you make a judgment.

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And sometimes that judgment's right,

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and sometimes that judgment's wrong.

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In this case, on the left-hand image, it's asymmetrical.

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So if I see that it seems as if it's more

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right-sided or left-sided or unilateral density,

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I'm gonna suggest this is a subdural

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hematoma along the posterior falx.

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Coming to the area of the torcula and layering

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onto the top of the tentorium on the right side.

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Because it's asymmetrical, this one symmetrical, more

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likely going to suggest that this is just a dense falx.

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Now, if you're in the situation where you're

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just uncomfortable with it, then recommend

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a follow-up study to see whether it evolves.

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But the surgeon is not going to

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operate on a very small, thin,

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posterior falx or tentorial subdural hematoma.

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Another example, in this case,

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dense falx, dense tentorium.

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More on the left side than the right side.

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But I look anteriorly.

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This anterior falx is also dense.

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Well, in this case, the patient had

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a subdural along the falx that was

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going from anterior to posterior.

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This one again, I would call positive.

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This one's pretty obviously positive.

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This is actually a follow-up to the previous case.

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This was the initial scan. I did call a small subdural

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hematoma along the posterior falx and going to the

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tentorium. We got a follow-up scan, and you can see

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that it actually enlarged in size in this example.

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So,

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judgment it is. It is a judgment call, and if you are

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uncomfortable with it or you haven't developed a

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frame of reference for good judgment, it's appropriate

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to ask for a follow-up study in order to clarify

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whether this is a subdural hematoma that may grow,

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or whether it's a tiny subdural hematoma that's

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inconsequential, or whether it's just a dense falx.

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Here.

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Another example, tentorium on the—

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left side more dense than the

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tentorium on the right side.

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How about this side?

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Both sides are a little bit dense

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for tentorial subdural hematomas.

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I'd like to reconstruct the thin

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sections into the coronal plane,

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and then look at this tentorium on that basis.

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If it remains a thin tentorium that is symmetric

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in density, I do not call a subdural hematoma.

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If there is any asymmetry from right to left,

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or asymmetry in the density of the tentorium,

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then I will call it. Sometimes you're just in

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the plane of the horizontal portion of the

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tentorium on an axial scan, so it looks

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thicker than the contralateral side.

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In this case, I'm concerned about

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this as a subdural hematoma.

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I'm also concerned along the anterior falx here

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that there may be blood products associated here.

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It looks as if—if this is not bone—like

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there may be some parenchymal hemorrhage.

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So now I have a potential for a coup-contrecoup injury,

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and I'm more likely to call this a positive finding.

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This I would pass

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as just being a dense tentorium,

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with no other findings on the CT scan.

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Similarly, you often have patients where you

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are wondering whether there are blood products

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on the sinus itself, and once again, use

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symmetry. If it's asymmetrical, one side to the

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other, it's more likely to be a subdural collection

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along the sinus or an epidural collection.

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Dissecting the sinus, as you see in this case where

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it's a bilateral collection, which is crossing

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the midline—an epidural hematoma secondary to

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a transverse sinus injury.

Report

Faculty

David M Yousem, MD, MBA

Professor of Radiology, Vice Chairman and Associate Dean

Johns Hopkins University

Tags

Trauma

Neuroradiology

Emergency

CT

Brain

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