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Midline Shift

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This was a 44-year-old homeless person

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who was brought in by the police

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after loss of consciousness.

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As we scroll through this case,

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we see that there appears to be midline

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shift at the level of the

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septum pellucidum.

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Let's measure that.

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It measures 7 mm,

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and therefore, is significant left-to-right shift.

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The question is,

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what is the cause of that left to right shift?

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Sometimes it could be due to volume loss

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on the right side due to atrophy.

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But we are not seeing

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subarachnoid space dilatation on the right side.

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As we continue to scroll further superiorly,

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we're not seeing a parenchymal hematoma.

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We are seeing some bowing of the falx subtly

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up anteriorly.

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You'll might note that the subarachnoid space,

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overlying the right frontal convexities medially,

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is demonstrated,

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but not on the left side.

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So this is a quandary.

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What is the source of that midline shift?

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Well, hopefully, you would have identified that

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the juxtacortical white matter,

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which is going far out to the periphery on the right

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side and in the occipital region on the left side,

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does not extend to the periphery as far on the left side.

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Let me use my magic pen.

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What I'm talking about is this amount of white matter,

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inward displacement compared to the white matter

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on the right side, is one of the markers

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for an isodense subdural.

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And you can see that actually the cortical margin on the

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left side is located where I've

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drawn my arrow and my line.

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Although, you do not see a hyperdense collection in this

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individual, by virtue of the displacement inward of the

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Juxtacortical white matter, the degree of mass effect,

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and in some cases, the effacement of the sulci,

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that this patient has an isodense subdural hematoma.

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Now,

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this patient may have lost consciousness days ago

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and been found subsequently, and therefore,

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we could identify this as a subacute in age isodense

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subdural, or we would check the hematocrit,

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see whether the patient is anemic,

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in which case, it would be potentially an acute

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isodense subdural hematoma.

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No matter what,

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if we were to measure this,

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we would find that the collection is 13 mm thick,

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exceeding the 10 mm thick criteria for surgical intervention.

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And that, as well as the 7 mm of midline shift,

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would lead the neurosurgeons to intervene in this patient.

Report

Description

Faculty

David M Yousem, MD, MBA

Professor of Radiology, Vice Chairman and Associate Dean

Johns Hopkins University

Tags

Vascular Imaging

Vascular

Trauma

Neuroradiology

Interventional

Emergency

CT

Brain

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