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Arteriovenous Malformation

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Aneurysms are a more common source of "worst"

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headache of life and subarachnoid hemorrhage

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than arteriovenous malformations or fistulae.

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Nonetheless, each of them may cause

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subarachnoid hemorrhage and bleed and

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lead to the presentation of headache.

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This was a relatively subtle example of

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a CT scan where we noticed that there

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were multiple areas of calcification.

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And hyperdensity without evidence

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of subarachnoid hemorrhage.

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These multiple little calcifications raise the

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possibility of things like cysticercosis or a

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calcified neoplasm such as oligodendroglioma.

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You could see that there is a little bit

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of midline shift at the level of the septum

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pellucidum, and this lesion had some mass effect.

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The patient was referred for MRI scanning.

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Whoa.

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So here we see on the MRI scan that this

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is a very large arteriovenous malformation.

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We do indeed have mass effect with midline

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shift at the level of the septum pellucidum, but

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it's due to this lesion that has multiple

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flow voids of an arteriovenous malformation.

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And this is the T2-weighted scan.

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Here we have post-gadolinium.

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On the post-gadolinium hand scan,

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you might say, "Well, it's an enhancing lesion.

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Maybe it's a tumor."

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The key here is to identify flow-

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related phase ghosting artifact.

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You notice that there is something that is coursing

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across the plane here, identifying that there

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is vascular flow pulsation from this lesion,

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which is indeed an arteriovenous malformation.

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So, subarachnoid hemorrhage may be

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associated with arteriovenous malformations.

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The rate at which an arteriovenous malformation

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bleeds into the subarachnoid space

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is quoted as 1 to 2% per year and, therefore,

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less than the asymptomatic aneurysm, which

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bleeds at approximately 2 to 3% per year.

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One of the benefits of using MRI for the evaluation

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of an arteriovenous malformation is that if you see

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hemorrhagic products, hemosiderin staining

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associated with the AVM, that suggests that the

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lesion has bled in the past and, therefore, the

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rate of bleeding in the future is higher if it

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has demonstrated previous hemorrhage than if

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it has not demonstrated previous hemorrhage.

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So, this is another example of a

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source of the "worst headache of life."

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Here is an angiogram showing an

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arteriovenous malformation.

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You have the

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sagittal T1-weighted MRI scan.

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When we look at an arteriovenous malformation, we also

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look at the drainage pattern and the size of the lesion.

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And this is because of something known

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as the Spetzler-Martin AVM grading system.

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This is a grading system that tells the surgical

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complication rate or the outcome with surgery

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for arteriovenous malformation. In this

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grading system, there are three components: the

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size of the arteriovenous malformation,

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and whether or not it affects eloquent cortex.

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By that, we mean the motor strip,

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speech areas, etc.

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And the drainage of the lesion—if it's

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less than three centimeters, it gets one point.

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If it's three to six centimeters, it gets two points.

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If it's greater than six centimeters, it gets

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three points.

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If it involves an eloquent area, we give it a point.

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If it has deep drainage, it gets a point.

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If it's superficially draining to superficial veins

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or to the superior sagittal sinus, as opposed

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to deep drainage to the internal cerebral

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vein, straight sinus, or vein of Galen.

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Again, these factors suggest a better

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surgical outcome when the numbers are lower.

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A worse surgical outcome may lead

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the surgeon to suggest trying

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endovascular treatment or even radiation

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treatment for the arteriovenous malformation.

Report

Faculty

David M Yousem, MD, MBA

Professor of Radiology, Vice Chairman and Associate Dean

Johns Hopkins University

Tags

Vascular

Neuroradiology

MRI

Emergency

CT

Brain

Angiography

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