The document discusses types of strokes, focusing on ischemic (85%) and hemorrhagic (15%), and outlines the role of non-contrast CT scans as the first imaging modality for acute ischemic stroke evaluation. It details the stages of stroke progression, findings in various time frames, and emphasizes the importance of CT in excluding hemorrhage and diagnosing strokes. Additionally, the document describes increased intracranial pressure, its symptoms, and potential treatments.

1. Stroke
Dima Lotfie
13901022

2. Types of stroke
• Ischemic 85% and hemorrhagic 15%.

3. Non contrast CT Scan in stroke
• First line imaging modality for the evaluation of acute ischemic stroke.
• Advantages:
1. Widespread availability
2. Short scan time
3. Non-invasive
• The only limitation is limited sensitivity in the acute setting.

4. Goals of CT Scan in the acute setting
1. Exclude intracranial hemorrhage, which would preclude
thrombolysis.
1. Look for any early features of infarction
1. Rule out any other intracranial pathologies that may mimic a stroke,
such as tumors.

5. Stages
• Early hyper-acute: < 6 hours
• Late hyper-acute: 6 – 24 hours
• Acute: 24 hours - 1 week
• Subacute: 1 – 3 weeks
• Chronic: > 3 weeks.

6. Immediate findings
• The earliest CT sign visible is a hyperdense
segment of a vessel (mostly seen in the
middle cerebral artery) representing direct
visualization of the intravascular
thrombus/embolus.

7. Early hyperacute findings
• Subtle loss of grey-white matter
differentiation in the lateral margin of
the insular cortex (insular ribbon).
• Cortical hypodensity with associated
parenchymal swelling.

9. Acute findings
• With time the hypodensity and swelling
(due to break down of BBB) become
more marked resulting in a significant
mass effect. This is a major cause of
secondary damage in large infarcts.
• Maximum swelling occurs during the
first week, typically on day 3.

10. • In this case the swelling is so severe, a
decompression craniotomy was needed.

11. Subacute findings
• As time goes on, the swelling starts to
subside and the density increases due
to small amounts of cortical petechial
hemorrhages. (Fogging phenomenon)
• Can mimic a normal CT Scan.

12. Fogging phenomenon.

13. Chronic findings
• A region of low density with negative mass effect.
• Focal loss of tissue leaving a vague “ghost” of the
previous gyral pattern.

15. MRI
• More time consuming
• Less available
But has significantly higher sensitivity and specificity in the diagnosis
especially in the first few hours of onset.

16. • Axial FLAIR image demonstrates intra-arterial high signal in the left
middle cerebral artery (MCA) of this patient with early stroke.

17. • Fluid attenuated inversion recovery MRI
• Diffusion weighted MRI
• Apparent diffusion coefficient MRI

18. Increased Intracranial Tension
• normal ICP is 5 - 15 mmHg.
• Causes of high ICP:
1. Head trauma
2. Hydrocephalus
3. Intracranial tumors
4. Hepatic encephalopathy
5. Cerebral edema

19. • Increased ICP can lead to death or devastating neurological damage
by:
1. Reducing cerebral perfusion pressure (CPP)
2. Causing cerebral ischemia
3. Compressing and causing herniation of the brainstem or other vital
structures.
• Symptoms:
1. Headache (worse in the morning)
2. Projectile vomiting
3. Blurry vision
4. Altered level of consciousness
5. Cushing triad: Bradycardia + hypertension + irregular respiration.

20. Treatment
• Elevate the head (promotes more venous drainage)
• Diuretics: Mannitol
• Hyperventilation
• Sedation +/- muscle relaxants
• Hemicraniotomy
• Treat the underlying cause.

21. References
• https://radiopaedia.org/articles/ischaemic-stroke
• Medscape