imaging

Question 1

what is the imaging test of choice in suspected acute stroke?

Answer 1

non-contrast CT

Question 2

4 CT signs of stroke

Answer 2

1 - dense middle cerebral artery (MCA)
2 - loss of grey-white differentiation
3 - loss of insular ribbon
4 - effacement of sulci

2-4 are signs of cytoxic edema

Question 3

how long can a CT still be normal after an acute stroke?

Answer 3

6-24 hours

Question 4

why is the MCA dense in acute stroke?

Answer 4

clotted blood in the vessel

Question 5

what is tPA?

Answer 5

tissue plasminogen activator, treatment for acute stroke within 3 hour window, with only precluding factor being hemorrhage on a CT

Question 6

what can preclude tPA treatment?

Answer 6

hemorrhage on a CT

Question 7

what is the gold standard for identifying dead brain tissue after a stroke?

Answer 7

• brightness maintained for 10-14 days on diffusion imaging MRI indicates irreversible injury

Question 8

potential false positives for dead brain tissue

Answer 8

abscess, hemorrhage, MS

Question 9

common characteristics of epidural hematoma

Answer 9

• 85-95% underlying fracture
• won’t cross bone sutures
• usually at site of impact
• biconvex
• better prognosis than others

Question 10

management of EDH

Answer 10

• if less than 30cc’s, thinner than 15mm, less than 5mm midline shift, glascow coma scale greater than 8, manageable without operation
• 30cc’s should be evacuated no matter what
• GSC less than 9 with anisocoria (uneven pupils), evacuate ASAP

Question 11

common characteristics of SDH

Answer 11

• crescentic
• can be coup or countercoup
• midline shift and thickness important
• worse prognosis than EDH

Question 12

management of SDH

Answer 12

• thickness greater than 10mm or midline shift greater than 5mm should be evacuated
• GCS less than 9, ICP should be monitored
• decrease in GCS by 2 or more, increased ICP, or fixed and dilated or asymmetric pupils are indications for evacuation even if thickness and midline shift criteria are not met

Question 13

where is the midline shift measured?

Answer 13

• foramen of monro

- (A/2) - B

Question 14

what is the #1 cause of SAH?

Answer 14

trauma

Question 15

treatment of SAH?

Answer 15

no specific treatment

Question 16

where are you most likely to find hematoma due to contusion?

Answer 16

anterior/inferior frontal

anterior temporal

Question 17

contusion hematoma gets bigger and more pronounced over what period of time?

Answer 17

2-3 days

Question 18

pathophys of diffuse axonal injury

Answer 18

most axons not injured, but cascade begins that leads to cell death over 24 hours

Question 19

where find diffuse axonal injury?

Answer 19

grey/white interface, midbrain, corpus callosum

Question 20

CT vs MRI in trauma

Answer 20

• get CT first because it identifies all surgically important lesions
• MRI is better at detecting SDH, EDH, contusion, axonal injury (important for unexplained continued deficits)