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Idiopathic Intracranial Hypertension (IIH)

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What are the other entities that are

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associated with worse headache of life?

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Well, pseudotumor cerebri, or what we now call

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idiopathic intracranial hypertension, is another

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entity that is associated with severe headaches.

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The typical patient that is, uh, has been

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described with a patient who has pseudotumor.

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Cerebri is an, uh, overweight

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individual who may show papilledema on clinical

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evaluation. The papilledema is a manifestation of

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that element of increased intracranial pressure,

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which is associated with pseudotumor cerebri.

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The imaging findings here are pretty dramatic.

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Here,

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we see that the patient has an enlarged

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empty sella, has enlargement of the Meckel

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cave region with the fifth cranial nerve.

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Bilaterally, here you notice that the patient has

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enlargement also of the optic nerve sheath complex.

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These are very prominent here, and at least on

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one of them, it looks as if there is papilledema

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that is reverse cupping at the junction between

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the optic nerve and the back of the globe.

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Here we have flattening at the

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back of the globe bilaterally.

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It's no longer that normal rounded spherical shape

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with dilatation of the optic nerve sheath complex,

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and much more tortuosity of that optic nerve

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sheath complex in and out of plane in this entity.

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The ventricles are usually

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normal to slightly small in size.

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You know when you have the

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high intracranial pressure?

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There's a possibility

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you might see actually small ventricles, so pap

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edema, dilated optic nerve sheath complex, tortuous

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optic nerve sheath complex, empty sella, dilated CSF

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spaces in this case associated with Meckel's cave.

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You can see it associated with some arachnoid

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granulations, and then collapse of the venous

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sinuses at the optic nerve sheath complex.

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Injunction with the globe, you may occasionally see

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high signal intensity on DWI imaging suggestive of

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papillitis, idiopathic intracranial hypertension.

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Pseudotumor cerebri has been associated with

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narrowing of the venous sinuses, and it's

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usually we're talking about the transverse sinus.

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This raises the possibility of sort of

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the quote-unquote chicken versus the egg.

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Is the intracranial hypertension, that high

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pressure collapsing the venous sinuses and

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causing them to look like there's a stenosis?

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Or does the stenosis itself lead to back

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pressure venous congestion, which would cause

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increased intracranial pressure?

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It's not really clear.

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What is clear is that a lot of patients do have

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sinus stenosis who have idiopathic intracranial

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hypertension, and if you stent that sinus and

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improve the flow through that sinus, you do

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see that the patient's symptoms get better.

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The major symptoms here are gonna be headache.

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However, the one that

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concerns us the most is the visual loss

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that can occur with pseudotumor cerebri, and

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that visual loss can become permanent if you

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have persistent high intracranial pressure.

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So narrowing of the sinuses.

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Now, please understand that asymmetry from

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right to left in the transverse sinus is

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the norm; we often see one dominant

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venous sinus, transverse sinus.

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So it's not until you see a focal area of narrowing

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that you would be concerned about venous sinus

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stenosis in idiopathic intracranial hypertension.

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You may see it IIH, or you may see PSC,

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pseudotumor or PTC for pseudotumor cerebri.

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Here's another example.

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In this case,

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the narrowing of the venous sinus was

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secondary to arachnoid granulations.

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You always have to be cognizant of the

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potential pitfall of calling a sinus narrowed

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when all you're seeing is a focal indentation

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of the sinus at an arachnoid granulation.

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So these are the little bright things on T2, a scan

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associated with the course of the transverse sinus.

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Maybe an arachnoid granulation, which, as you

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can see, may even invaginate into the sinus and

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look like it's causing narrowing, or in this

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case, maybe even a thrombus within the sinus.

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Here's another arachnoid granulation, and as you can

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see, these arachnoid granulations invaginate into the

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sinus and cause narrowing, but this is a normal variant.

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This is not due to the pseudotumor

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cerebri, another sinus here.

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Another arachnoid granulation infiltrating into

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the sinus, in this case involving the bone as well.

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Here's one that's involving the superior sagittal sinus

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with what looks like a filling defect in the sinus,

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but it's really these high signal intensity on T

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2A scan, arachnoid granulation, invaginating

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into the superior sagittal sinus or transverse sinus,

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and causing an appearance of sinus stenosis.

Report

Faculty

David M Yousem, MD, MBA

Professor of Radiology, Vice Chairman and Associate Dean

Johns Hopkins University

Tags

Neuroradiology

MRI

Idiopathic

Emergency

Brain

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