Stephen B. Lewis MD FRACS

Department of Neurosurgery

University of Florida

• General overview

• Ischemic strokea) Thrombotic vs embolic

b) Factors affecting extent

c) Effect of location

c) Lacunar

c) Territorial

• Hemorrhagic stroke

a) Aneurysms

b) Hypertension

• Cerebral herniation

Stroke

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

• Heart

• Sites of atheromatous disease

- aorta

- common carotid bifurcation

- distal intracranial vertebral artery

- proximal half basilar artery

- perforating microvessels

Favored locations

Stroke

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

PCABasilar apex

Basilar A.

Vertebral A.

ACAMCA

Stroke: factors affecting extent of stroke

• Anastomotic channels- ACoA- PCoA- Between territories

ACA

MCA

Anastomotic vessels

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

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

ICAM4

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

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

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)

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

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

100%

0%minutes hours days months

% NORMAL NEUROLOGIC FUNCTION

TIME

EMBOLIC STROKE

THROMBOTIC STROKE

Stroke: territorial strokes

years

Onset of clinical symptoms

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

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%

Cerebral aneurysms• Symptoms due to SAH:

- sentinal headache

- “worst headache of life”

Stroke: hemorrhagic strokes

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

Stroke: hemorrhagic strokes

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

• Rigid structure

• Contains

- brain

- blood

- CSF

• Additional contents may

result in raised pressure

Stroke and cerebral herniation

Causes of raised ICP• Hypertensive hemorrhage

• Subarachnoid hemorrhage

• Territorial stroke

• Hydrocephalus

Hydrocephalus

Hypertensive hemorrhage

Subarachnoid hemorrhage Territorial stroke

Stroke and cerebral herniation

Cerebral herniation - effect of raised ICPSubfalcine herniation

Contralateralventriculomegaly

Duret hemorrhages

Transtentorialherniation

Tonsillar herniation

Stroke and cerebral herniation

Subfalcine herniation

Anterior cerebral artery

- medial surface

Stroke and cerebral herniation

• Uncal herniation compressing PCA onto 3rd cranial nerve

LR

PCA occlusion- occipital lobe infarction

Stroke and cerebral herniation

• General overview

• Ischemic strokea) Thrombotic vs embolic

b) Factors affecting extent

c) Effect of location

c) Lacunar

c) Territorial

• Hemorrhagic stroke

a) Aneurysms

b) Hypertension

• Cerebral herniation

Stroke