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53 Cards in this Set

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  • Back
What is the imaging modality of choice in a comatose patient, neural deficit patient, or where there is evidence of brain trauma?
CT!
What does CT measure?
Density of tissues.
For a brain injury should non-contrast or contrast enhanced CT be used?
Non-contrast enhanced CT
Why should a contrast-enhanced CT NOT be used?
Small hemorrhages can be masked by the iodinated contrast.
When should an MRI be done for a head injury?
After CT, if necessary.
For a head injury, what is MRI good for?
MRI plays a supporting role. It is good for detecting subtle hemorrhages.
What skull fractures are the most clinically important b/c they require neurosurgical intervention?
Depressed skull fracture.
What is a pneumocephalus sphenoid fracture?
If the sinuses get fractured, air can get into the subarachnoid space and will be seen on CT as dark spots.
What occurs when the brain hits the bony ridges in the skull?
Brain contusion.
What type of contusion is seen directly beneath the site of injury?
Coup contusion.
In what lobes of the brain is a coup contusion most common?
Frontal & temporal lobes
What type of contusion occurs at the site opposite from impact, with minimal injury at site of impact?
Contrecoup contusion
In a contrecoup injury, what does the inferior frontal lobe contact?
Orbital roof & cribiform plate
In a contrecoup injury, what do the temporal tips contact?
Sphenoid wing
On a gross specimen, what will the site of contusion look like?
Hemorrhagic in appearance.
In a hemorrhagic contusion, what is bright on CT? What is dark on CT?
Blood will be bright on CT. The darkness surrounding is edema.
What type of treatment do physicians give for a small contusion?
None-if it is small, nothing may be done except "watch & wait" to make sure they don't develop into a subdural hematoma.
What type of injury may be secondary to child abuse?
Contusion.
Bright subacute blood in a cortical contusion and a subdural hematoma on the other side of the brain in a child should raise suspicions of what?
Chronic child abuse.
What can help determine the age of the bleed and injury on the MRI?
Blood changes its chemical composures over time, having different appearances on MRI.
On an MRI, what is the difference between acute blood and older blood?
Acute blood will be brighter than older blood.
What color is blood on CT?
Blood is hyperdense on CT.
In what type of hematoma does low-pressure venous bleeding of bridging veins (b/w the cortex & venous sinuses) dissect the arachnoid away from the dura and layers out along the cerebral convexity?
Subdural Hematoma (SDH)
What are the 3 stages of subdural hematoma injury?
1.Acute
2.Subacute
3.Chronic
How many days after an acute injury, is a subacute subdural hematoma seen?
3-7 days after injury.
How many days after an acute injury, is a chronic subdural hematoma seen?
2-3 weeks after injury, developed from an untreated acute SDH.
What does an "acute on chronic" subdural hematoma mean?
Subacute/Chronic subdural hematomas may keep bleeding very slowly, and could eventually cause acute rebleeding.
What will the appearance of a subdural hematoma be on CT?
Cresecent-shaped hyperdense area along the brain surface.
What is the difference between a subdural hematoma and an epidural hematoma?
Subdural hematoma will cross suture lines, and epidural hematoma will not.
Do subdural hematomas usually cross the tentorium or the falx?
NO
In a subdural hematoma, what does new blood on top of old blood (bright upon darker area) indicate?
Acute on chronic SDH
Why would a subdural hematoma have to be drained?
B/c of the mass effect and midline shift.
Why is subtle subdural hematomas difficult to see?
b/c bone and blood are similar density on CT
All of these individuals are likely to get what?
-Blunt head trauma
-Coagulopathy
-Hemophiliacs
-Patients taking anticoagulants (Coumadin)
-Alcholics
SDH
What type of hematomas are much less common than SDH?
Epidural hematoma.
What shape does an epidural hematoma have on CT?
Bioconcave appearance on CT.
What type of EDH accounts for 90% of EDHs?
Arterial type-->tear in middle meningeal artery
What type of EDH accounts for 10% of EDHs?
Venous type-->tear of the meningeal vein or venous sinus laceration.
In the posterior fossa tear of what sinus causes and EDH?
sigmoid sinus
In the parasagittal region, tear of what sinus causes EDH?
superior sagittal sinus
How does EDH appear on CT?
Hyperdensity, and has a lens shape.
Does EDH cross suture lines?
NO
Can EDH cross the midline & tentorium?
Yes
Where are the majority of EDH's located?
Unilateral and supratentorial.
What is the shape of an SDH vs. EDH on CT?
SDH-->crescent shape
EDH-->lens shape
Are EDH's a neurosurgical emergency?
Yes, they rapidly expand.
Is an SDH or EDH an emergency?
EDH is an emergency. With SDH's, if they are subtle, we may watch and wait.
Which will cross the tentorium? SDH vs. EDH
EDH
In a diffuse axonal injury, where is the injury the greatest?
The injury tends to be severe in the brainstem just below the thalamus.
Where in the cerebrum is a diffuse axonal injury most likely to occur?
Happens typically where gray meets the white matter.
Why is a diffuse axonal injury most likely to occur in the interface between gray and white matter?
B/c gray and white matter have different densities, and so they don't stop at the same time during quick deceleration.
What is more sensitive in detecting a diffuse axonal injury? CT or MRI?
MRI
Is a diffuse axonal injury associated with areas of hemorrhage?
Yes