This document provides information about cerebrovascular accidents (strokes) as visualized on CT scans. It defines a stroke and lists its main causes as cerebral infarction, intracerebral hemorrhage, or subarachnoid hemorrhage. CT is described as the best initial test for evaluating strokes, as it can detect hemorrhages which would rule out thrombolysis treatment, or see early signs of infarction. The document outlines what normal, early, and late stage strokes appear as on CT scans, including examples of dense artery signs, intracerebral hemorrhages, and subarachnoid hemorrhages.

1. Cerebrovascular Accidents
Jeetendra Bhandari

2. Normal CT
Index:
• T temporal lobe
• P  pituitary gland
• Dor sel  dorsum sellae
• Pe  petrous bone
• C  cerebellar hemisphere
• V  vermis
• IV  fourth ventricle

3. Index:
• Syl  fissure Sylvian fissure

4. Index:
• LV  lateral ventricle
• Th  thalamus
• Int capsule  internal
capsule
• III  third ventricle

5. Index:
• CP choroid plexus
• LV lateral ventricle

6. Index:
• CR corona radiata
• O occipital lobe

9. Major intracranial arteries
Index:
• ACA anterior cerebral artery
• ACommA  anterior communicating artery
• AICA  anterior inferior cerebellar artery
• bas art  basilar artery
• CarotidA  carotid artery
• MCA  middle cerebral artery
• PCA  posterior cerebral artery
• PCommA  posterior communicating artery
• PICA  posterior inferior cerebellar artery
• SCA  superior cerebellar artery
• VertA  vertebral artery

10. Stroke
• Defined as a sudden, focal neurological deterioration due to a
disturbance in the blood supply to the brain
• Causes includes:
• Cerebral infarction, which may be due to in situ thrombus or embolus from
the proximal artery or heart
• Intracerebral hemorrhage
• Subarachnoid hemorrhage
• Acute management of thromboembolic infarct is to destroy clot with
thrombolysis, but is contraindicated in the presence of hemorrhage –
therefore CT is the best first test

11. Outcome of CT performed in Stroke
• Presence of hemorrhage rule out thrombolysis treatment
• Stroke mimics are conditions that present like stroke, such as a
subdural hematoma or brain tumor
• Normal scan either means the patient is not having a stroke or is at
the very early stages of a stroke before the CT becomes abnormal and
therefore thrombolysis can be carried out
• Then there are the early signs of a stroke seen on CT. The dense
artery sign is high density clot visualized within a major intracranial
artery.

12. Dense artery sign. Unenhanced CT showing
acute thrombus in the right middle cerebral
artery (arrow). Early sign seen on CT.

13. (Right) Initial CT scan a few hours after the onset of symptoms showing low attenuation in the posterior cerebral artery territory
with swelling causing effacement of the local sulci (arrow).
(left)CT scan a month later showing low attenuation gliotic change in the same territory and atrophy causing localized expansion
of the lateral ventricle and widening of the sulci (arrow).

14. Intracerebral hemorrhage
• Acute hemorrhage seen on CT as high attenuation, frequently causing
a mass effect
• Initial high density lessens over time, leaving a low density area
indistinguishable from an infarct
• MRI can be useful in the follow-up of intracerebral hemorrhages to
exclude underlying vascular malformation or occult metastasis, which
may be obscured by the presence of blood
• If no cause identified, formal cerebral angiography may be required to
exclude a subtle vascular anomaly

15. Acute parenchymal hemorrhage. CT scan
showing the hematoma as a high density
area with local mass effect (H) in the left
frontal lobe

16. Subarachnoid Hemorrhage
• Spontaneous due to a ruptured intracranial aneurysm or vascular
malformation.
• CT best initial investigation to diagnose a subarachnoid hemorrhage
and to demonstrate the site of bleeding
• Recognized by high density blood outside the brain in the sulci,
Sylvian fissures and basal cisterns
• CT prevent the need for lumbar puncture and CSF examination, but
sensitivity of CT decreases with time after a hemorrhage and a
normal examination does not exclude the diagnosis

17. Subarachnoid hemorrhage. High density
subarachnoid blood can be seen in the
basal cisterns outlining the brain stem
(long arrow), the Sylvian fissures (short
arrow) and within the fourth ventricle
(curved arrow).
(Normal on top left)

18. Reference
• Rockall, Andrea, Hatrick, Andrew, Armstrong, Peter, Wastie, Martin.
Diagnostic Imaging, 7th ed.

19. Thank you!!!