This document discusses different types of stroke, including ischemic strokes caused by blockages and hemorrhagic strokes caused by bleeding. Ischemic strokes can be thrombotic due to local clots or embolic due to traveling particles. The location and size of blockages influences the effects. Small lacunar strokes in deep brain areas may be silent, while larger territorial occlusions can cause distinct neurological syndromes. Hemorrhagic strokes can arise from aneurysms, usually at artery bifurcations, or hypertension damaging small vessels. Raised pressure in the skull from stroke damage can cause herniation syndromes as the brain is compressed.

1. Stephen B. Lewis MD FRACS
Department of Neurosurgery
University of Florida

2. • General overview
• Ischemic stroke
a) Thrombotic vs embolic
b) Factors affecting extent
c) Effect of location
c) Lacunar
c) Territorial
• Hemorrhagic stroke
a) Aneurysms
b) Hypertension
• Cerebral herniation
Stroke

3. A sudden and often severe cerebral vascular catastrophe
that may temporarily or permanently impair brain function
Types
1. Ischemic: blockage within blood vessel
a. Thrombotic: locally generated obstruction
b. Embolic: occlusion secondary to traveling particle
originating proximally in bloodstream
2. Hemorrhagic: bleeding from blood vessel resulting in
clot formation within brain substance
or over its surface
Stroke

4. • Heart
• Sites of atheromatous disease
- aorta
- common carotid bifurcation
- distal intracranial vertebral artery
- proximal half basilar artery
- perforating microvessels
Favored locations
Stroke

5. Stroke: emboli
• Emboli lodge at bifurcations - ICA
bifurcation - basilar artery tip
• Final lodgement a function of: -
hemodynamic forces - size
• Perforator (lacunar) strokes -
thrombotic (local disease)
• Territorial strokes - embolic or
thrombotic
PCA
Basilar apex
Basilar A.
Vertebral A.
ACA
MCA

6. Stroke: factors affecting extent of stroke
• Anastomotic channels
- ACoA
- PCoA
- Between territories
ACA
MCA
Anastomotic vessels

7. Clinical example – when things fail
•46 yo rh WM
•Carpenter
•Very hot day – dehydrated, felt unwell
•Sudden onset of leg weakness
Stroke: factors affecting extent of stroke
MCA stenosis

8. Stroke: factors affecting extent of stroke
• Perforating vessels
- end arteries
- poor collateral supply
- lenticulostriates affected
Sylvian Fissure
M1 (pre-bifurcation)
M1 (post-bifurcation)
M2 segments
M3 segments
M4 segments (cortical branches)
Genu
Lenticulostriates
A2HA
ICA
M4

9. Stroke: effect of location
• Small perforating vessels
- may be silent (lacunes in putamen, others)
- may be devastating (lenticulostriates)
• Terminal large vessel occlusion
- large number of syndromes -
MCA upper div: facio brachial motor,
hemisensory loss, Brocas aphasia -
MCA lower div: Wernickes aphasia,
visual disturbance, behavioural

10. Stroke: effect of location
• Terminal large vessel occlusion
- dependent upon territory supplied
• PICA:
a) Vestibular nuclei – N&V
b) Inf cereb peduncle – ipsi ataxia
c) Spinal CN V – ipsi P&T face
d) CN IX – loss afferent limb gag rf
e) CN X – ipsi pharyngeal, laryngeal
paralysis
f) Spinal lemniscus (ST tract) – contra.
P&T from limbs & trunk
g) Desc sympathetics – ispi Horners

11. Stroke: lacunar strokes
• One-third of all ischemic strokes
• Etiology:arteriosclerotic occlusion of
perforators in the basal
ganglia, brainstem, and
centrum semiovale
• Associated with HTN and diabetes
• Lesions < 1.5 mm3
(often not seen on CT)

12. Stroke: lacunar strokes
Clinical example
Classical clinical syndromes
- Pure motor
- Pure sensory
• 56 yo rh WF
• Diabetes, hypertension, smoker
• Sudden onset left pure motor hemiparesis

13. Stroke: territorial strokes
• Two-thirds of all ischemic strokes
• Arterial branch or stem occlusions
• Etiology: embolic or local thrombosis
• Prognosis related to severity of
presenting symptoms, size of lesion,
and patient’s age & comorbidities

14. 100%
0%
minutes hours days months
% NORMAL
NEUROLOGIC
FUNCTION
TIME
EMBOLIC STROKE
THROMBOTIC STROKE
Stroke: territorial strokes
years
Onset of clinical symptoms

15. Supratentorial
- sudden motor/sensory deficit
- plus cortical symptoms such as aphasia, apraxia, neglect,
homonymous visual deficits
Stroke: territorial strokes
Infratentorial
- sudden motor/sensory deficit
- Plus additional brainstem or cerebellar
disturbances

16. Stroke: hemorrhagic strokes
• Cerebral arteries have subarachnoid course
• Aneurysms = outpouching of intima
• Aneurysms occur at bifurcation points
Cerebral aneurysms
ACoA 35%
MCA 20%
P Comm 25%
Vertebral 5%
Basilar 10%

17. Cerebral aneurysms
• Symptoms due to SAH:
- sentinal headache
- “worst headache of life”
Stroke: hemorrhagic strokes

18. Cerebral aneurysms
•49 yo rh W M
•Gradual onset:
- bumping into things
- inferior nasal field cut right eye
•Symptoms due to location
- mass effect on optic nerve
Stroke: hemorrhagic strokes

19. Stroke: hemorrhagic strokes

20. Stroke: hemorrhagic strokes
Hypertensive hemorrhage
• Rupture occurs in middle/distal portions
of penetrating arteries
• Incidence doubles with each decade
after age 35
• Hypertensive history (remote & recent)
• Occurs: basal ganglia, thalamus,
cerebellum, pons, deep white matter

21. • Rigid structure
• Contains
- brain
- blood
- CSF
• Additional contents may
result in raised pressure
Stroke and cerebral herniation

22. Causes of raised ICP
• Hypertensive hemorrhage
• Subarachnoid
hemorrhage
• Territorial stroke
• Hydrocephalus
Hydrocephalus
Hypertensive hemorrhage
Subarachnoid hemorrhage Territorial stroke
Stroke and cerebral herniation

23. Cerebral herniation - effect of raised ICP
Subfalcine herniation
Contralateral
ventriculomegaly
Duret hemorrhages
Transtentorial
herniation
Tonsillar herniation
Stroke and cerebral herniation

24. Subfalcine herniation
Anterior cerebral artery
- medial surface
Stroke and cerebral herniation

25. • Uncal herniation
compressing PCA onto 3rd
cranial nerve
LR
PCA occlusion
- occipital lobe infarction
Stroke and cerebral herniation

26. • General overview
• Ischemic stroke
a) Thrombotic vs embolic
b) Factors affecting extent
c) Effect of location
c) Lacunar
c) Territorial
• Hemorrhagic stroke
a) Aneurysms
b) Hypertension
• Cerebral herniation
Stroke