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Herniation resulting in Infarction

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This was a 56-year-old who was thrown from

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the motorcycle after a motor vehicle collision.

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The CT scan is quite dramatic

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in that the patient has

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a large amount of blood that has collected.

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If we start from superiorly,

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we see hemorrhage along the intrahemispheric fissure

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and a small subdural collection in a parafossean

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location. We also see that there is a large collection

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of irregular blood products

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which is seen overlying the

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right frontal and parietal

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lobes and extends to the temporal region.

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The collection we could measure,

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but it's clearly greater than 10mm

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in width and therefore as a surgical candidate

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actually measures 17mm.

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When we look to measure the degree of midline shift

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at the level of the septum plus C idem,

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we see that there is 10.8 mm of midline shift

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greater than the 5 mm that would normally be a

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surgical criterion,

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and these 2 would

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suggest that the patient requires

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no surgical intervention.

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You notice also that there is

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tissue which appears to be extending.

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The gray matter appears to be extending from

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right to left

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across the edge of the Falx

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over here, just too much gray matter here,

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and this represents the Subfalcine herniation

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that is due to the large collection.

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When we look further inferiorly,

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we see that there is tissue

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which looks unlike normal cerebellar vermis

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that is crossing the edge of the tentorium.

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The tentorial edge

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is seen

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on the left side here

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and on the right side incompletely. Seen

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because there appears to be brain tissue

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which is extending across from the right to the left.

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You note that the

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cistern on the right side

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has been displaced and the midbrain

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this is the cerebral aqueduct.

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The midbrain appears to be shifted from right to left.

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This is the area of the uncus or the amygdala

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and what?

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Whereas the normal amygdala is ending over here on the

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left side. On the right side, we see tissue

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which is effacing the cistern of the

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periaqueductal region,

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and so we have evidence of uncal herniation,

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probably evidence of

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transtentorial herniation of temporal lobe structures.

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This patient

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developed 3rd nerve palsy,

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the so-called blown pupil.

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So a blown pupil is largely secondary to compression

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of the oculomotor nerve,

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the 3rd nerve

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secondary to herniation of tissue

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into the perimesencephalic cistern

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where the 3rd nerve will

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be coursing, and this often happens with uncal herniation

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because of the numerous

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neurologic complaints, the

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size of the subdural hematoma

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and the degree of midline shift

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the patient underwent,

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nor surgical evacuation of the subdural hematoma.

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This is the post-operative evaluation.

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You see that in point of fact

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the patient had a craniotomy.

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By craniotomy, we mean that

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portion of the calvarium

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was removed and not replaced,

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so craniotomy. We replaced the bone.

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Craniectomy we've removed the bone

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and this allows the brain to expand outward,

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rather than causing midline shift and right-left shift

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you notice that the patient still.

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Has an element of midline shift,

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so as we measure

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here and to the septum plus idum

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it now measures approximately 5mm,

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whereas previously it was approximately 11mm.

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So they have relieved

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the midline shift.

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We no longer see

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very much in a way of subfalcine and

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herniation of tissue

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a little bit right over here

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of the falx tent,

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and as we look down at the

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uncus,

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there's dramatic improvement here. Here is the uncus,

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the mediotemporal

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lobe on the left side.

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Here is now that tentorial edge

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with no apparent impression

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of the uncus, maybe a little bit over here,

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but that's not that much

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different from the contralateral side,

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so the right side a little bit

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and we have a more normal appearance to the

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cerebellar tissue,

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and along the tentorial edge

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patient has a collection of blood along the posterior

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portion of the occipital lobe

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as well as on the posterior falx,

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but at this juncture along with that interhemispheric

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at this juncture, we'd say looks pretty good

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post-operative evaluation.

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This is 24 hours later.

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24 hours later

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we are seeing low-density areas within the anterior

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medial right frontal lobe.

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Those with super good eyes might

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also note a low-density area in the

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posterior portion of the mediotemporal

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on the right side. Compared with the left side

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patient still has the craniotomy

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and the midline shift is still resolving

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not much in a way of uncal herniation,

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so let's go back

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to the previous. Scan

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one day

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earlier. That was the immediate post-operative scan.

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Now in retrospect

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we might wonder

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about the low-density in the

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medial frontal lobe on the right side

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as well as this area of low density

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more posteriorly,

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what has happened?

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Well, we get more clarity if we look at the MRI scan

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and this MRI scan

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was performed

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48 hours after surgery.

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This is the diffusion-weighted scan.

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48 hours after surgery.

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Remember for diffusion-weight imaging. It's our best

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sequence to look for infarcts.

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What do we see?

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We see high signal intensity in the medial

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temporal lobe

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extending to involve the occipital cortex

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on the right side

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as we proceed further superiorly,

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we are seeing

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areas on the posterior cingulum and parietal lobe

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as well as the medial frontal lobe of infarction.

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There's also an area over here' that will deal with

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that is really related to susceptibility artifact

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what happened?

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This is an example of one of the complications of

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head trauma that leads to a secondary injury.

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This patient's subfalcine herniation

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led to compromise of the anterior cerebral artery,

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leading to infarction

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of the medial aspect of the right frontal lobe.

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This patient's

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uncal herniation and transtentorial herniation

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led to compromise of the posterior cerebral artery

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as well as potentially the anterior choroidal artery

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leading to infarction of the medio temporal lobe

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as well as the occipital lobe

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despite almost

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immediate evacuation of this collection.

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So infarctions of

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occipital lobe, temporal lobe, and frontal lobe

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demonstrate on the

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diffusion-weighted scan and ADC maps

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affecting medial frontal lobe,

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parietal lobe,

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portions of occipital lobe, and even the temporal lobe

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from the vascular complications of herniation.

Report

Description

Faculty

David M Yousem, MD, MBA

Professor of Radiology, Vice Chairman and Associate Dean

Johns Hopkins University

Tags

Vascular Imaging

Vascular

Trauma

Spine

Skull Base

Orbit

Non-infectious Inflammatory

Neuroradiology

MRI

Interventional

Head and Neck

Emergency

CT

Brain

Bone & Soft Tissues

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