8. Emergency Neuroradiology

Question 1

What is the classification of strokes?

Answer 1

Ischemic stroke (85%)
- cardiogenic embolic
- large artery thrombosis (atherosclerotic disease)
- small penetrating artery thrombosis
- cryptogenic
- other

primary hemorrhagic stroke (15%)
- subarachnoid hemorrhage
- intracerebral hemorrhage
- subdural hemorrhage
- epidural hemorrhage
- intraventricular hemorrhage

Question 2

What is the therapeutic window for ischemic stroke?

Answer 2

4.5 hours for proper diagnosis and initiation of treatment

Question 3

What are the types of intracranial bleeding?

Answer 3

• acute epidural hematoma
• subdural hematoma
• acute subarachnoidal hematoma

Question 4

What are the characteristics of acute epidural hematoma?

Answer 4

• lens shaped
• due to trauma, usually injury to the meningeal artery
• acutely hyperdense and gradually decreases density (CT image)
• due to arterial origin it grows fast and needs urgent intervention
• often associated with skull fracture

Question 5

What are the characteristics of subdural hematoma?

Answer 5

• trauma, usually due to tearing of bridging cortical veins
• goes into the fissures but does not cross the midline
• acutely hyperdense and gradually decreases density (CT)

Question 6

What are the characteristics of subdural hematoma?

Answer 6

• most often due to rupture of a berry aneurysm
• crescent shaped
• most commonly located in bifurcations of the circle of Willis
• hyperdense in the suprasellar cistern (CT)
• hyperintense in the first 12 hours (MRI, FLAIR)

Question 7

What are the signal intensities of hematomas on MRI?

Answer 7

for both T1 and T2

• methemoglobin hyperintense: late subacute stage
• hemosiderin hypointense: chronic stage

Question 8

Detection of bleeding

Answer 8

• CT is best for large acute hematomas (hyperdense)
• MRI is more sensitive for subacute and chronic hematomas and petechial bleedings

Question 9

What are herniations?

Answer 9

• life threatening emergency most probably due to space occupying lesions and/or increased intracranial pressure
• tonsillar herniation must be ruled out in case of increased intracranial pressure

Question 10

Imaging of acute spinal injuries

Answer 10

• in the brain, DWI can help differentiate between cysts and abscesses because abscesses have diffusion restriction due to the viscosity of pus (ie. spinal epidural abscess)
• myelon contusion is T2 hyperintense and non-enhanced on T1W