Pathology of Cerebrovascular Disease Dr Anim by sammyc2007

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									Pathology of Cerebrovascular Disease
By Prof. J.T. Anim Department of Pathology

Cerebrovascular Disease
Affected blood vessels
Intracranial vessels
Middle cerebral artery Anterior cerebral artery Basilar artery (posterior cerebral arteries)

Extracranial vessels
Carotid artery
Common carotid artery Internal carotid artery (external carotid artery)

Vertebral artery others

Brain: Blood supply

Brain: Blood supply

Arterial blood supply to the brain

Brain: Blood supply

Cerebrovascular Disease
Transient ischaemic attack (TIA)
A fully reversible neurological deficit often lasting for no more than a few minutes, but occasionally up to 24 hours.
No structural brain damage has occurred

Cerebrovascular Disease
Factors predisposing to TIA
Atherosclerosis
Superimposed hypotension Spasm of diseased vessel

Disorders in the neck (spondylosis) Other extracranial vascular diseases eg. embolism

Cerebrovascular Disease
Stroke
Rapid onset of a focal disturbance of cerebral function of presumed vascular origin and of more than 24 hours duration.
Permanent brain damage has occured

STROKE

Ischaemic/Occlusive

Haemorrhagic/Disruptive
Intraparenchymal

Thrombosis

Embolism

Hypotension Subarachnoid

Atherosclerosis

Cardiac

Pump failure
Hypovolaemia

Fibromuscular dysplasia
Arteritis

Extracranial vessels
Paradoxical

Mixed

Dissection

Other emboli

Stroke: Causes

Ischaemic Stroke
Atherosclerosis
Carotid artery
Common carotid Internal carotid (external carotid)

Vertebro-basilar system
Posterior cerebral
With normal BP, >90% cross sectional area reduction is necessary to impair blood flow

Ischaemic Stroke
Factors affecting tissue survival
Adequacy of collateral circulation State of systemic circulation
Reduced blood flow, cardiac pump failure, hypovolaemia, hyperviscosity

Serological factors
Low blood sugar, high blood sugar, hypoxia, elevated serum calcium, high blood alcohol

Ischaemic Stroke
Factors affecting tissue survival contd.
Changes within obstructing vascular lesion
Fragmentation and advancing of embolus Reactive vasoconstriction (spasm) Reperfusion – stunned cells may recover Propagation of thrombus – collateral occlusion Embolisation from previous thrombus

Ischaemic Stroke
Factors affecting tissue survival contd.
Resistance within microcirculatory bed
Hypertension Diabetes mellitus – thickened vessel walls Hyperviscosity Diffuse thromboses (low microcirculatory flow)

Oedema and raised ICP
Increased resistance to blood flow

Ischaemic Stroke
Intracranial vascular occlusion
Effects usually confined to area of supply of affected vessel

Extracranial vascular occlusion
Effects may be modified by collateral circulation Watershed infarction may be seen

Brain: Distribution of cerebral infarction

CNS Ischaemia
Selective vulnerability of CNS cells
Neurons – most sensitive Oligodendroglia Astrocytes Microglia Blood vessels
In descending order of sensitivity

Brain: Effect of global ischaemia

Consequences of global ischaemia

Effects of global ischaemia

CNS Ischaemia
Mild hypoxia
Selective neuronal necrosis eg. respirator lung

Moderate hypoxia
Neuronal necrosis Neuroglial necrosis Blood vessels and microglia are spared
Partial cerebral infarction

Ischaemic Stroke
Infarction (stroke)
Thrombotic – usually anaemic (may be haemorrhagic) Embolic – usually haemorrhagic, often multiple. Haemorrhagic nature due to:
Necrosis of vessel wall Lysis of embolus with restoration of some blood flow.

CNS Infarction
Vascular occlusion causes:
Necrosis of neurons, neuroglia and blood vessels 4-6 hrs. – coagulative necrosis 12-15 hrs. – sharp demarcation (swelling of neuropil) 24 hrs. – reactive changes
Proliferation of microglia, astrocytes, capillaries Inflammatory reaction

CNS Infarction
Infarction contd.
1-2 weeks – Swelling resolves
Softening Shrunken granular grey matter Accumulation of lipid-laden phagocytes (gitter cells) in infarcted area

Several months – shrunken cystic lesion traversed by glial fibrils and small blood vessels

Brain: Recent anaemic infarct

Brain: Older infarct showing cavity formation

Brain: Older infarct

Bilateral posterior cerebral infarcts

Brain: Recent haemorrhagic infarct

Brain: Haemorrhagic infarct

Brain: Haemorrhagic infarct

Brain: Multiple haemorrhagic infarcts

Brain: Relatively recent infarct - Histology

Brain: Older infarct showing ‘gitter’ cells

Brain: Older infarct - Histology

Brain: Old infarct with cavity formation - Histology

Brain: Laminar infarct

Brain: Watershed infarct

Brain: Very old infarct showing atrophy of hemisphere

CNS Infarction
Vertebro-basilar occlusion
Infarction of brainstem Infarction of cerebellum Infarction of posterior cerebral arterial territory

Clinical effects of basilar artery occlusion

Brain: Haemorrhagic cerebellar infarcts

Chronic CNS Ischaemia
Lacunae
Small cavities located deep within cerebral hemispheres (basal ganglia) and pons Elderly subjects - >90% with hypertension ? Small infarcts ? Expanded perivascular spaces ? Resolving haemorrhages Associated with vascular dementia
Multi-infarct dementia Binswanger’s disease

Brain: Lacuna in pons

Brain: Lacunar lesions

CNS Infarction
Venous thrombosis
Primary – non-infectious
Pregnancy, puerperium and oral contraceptives Haematological disorders Extreme dehydration
Haemorrhagic infarction

Secondary – pyogenic infections
Infections from sinuses, middle ear Compound fracture
Septic infarction

Brain: Bilateral haemorrhagic infarct – Sup. Saggital sinus thrombosis

Haemorrhagic Stroke
Brain and spinal cord substance (intraparenchymal) Subarachnoid Mixed

Haemorrhagic Stroke
Major predisposing factors
Hypertension Congenital anomalies Vascular malformations

Minor predisposing factors
Vasculitis Bleeding diatheses

Haemorrhagic Stroke
Primary intraparenchmal haemorrhage
Predisposing vascular changes include:
Fibrinoid necrosis Hyaline arteriolosclerosis (lipohyalinosis) Microaneurysms (Charcôt-Bouchard)

Sizes of haemorrhage
Massive - >3cm diam. Cerebral hemisphere
> 1.5cm diam. brainstem

Brain: Charcot-Bouchard microaneurysm

Brain: Common sites of spontaneous haemorrhage

Brain: Haemorrhage into basal ganglia

Brain: Massive hemispheric haemorrhage

Brain: Haemorrhage into basal ganglia

Brain: Pontine haemorrhage

Brain: Pontine haemorrhage

Haemorrhagic Stroke
Subarachnoid haemorrhage
Saccular aneurysm 65%
Females = males Developmental medial defect Superimposed degenerative changes eg. atheroma 15-20% multiple

A-V malformations Others (blood dyscrasias) No cause found

5% 5% 20%

Haemorrhagic Stroke
Subarachnoid haemorrhage
Secondary effects include:
Rebleeding Vasoconstriction (spasm) hydrocephalus

Brain: Distribution of saccular (berry) aneurysms

Brain: Multiple berry aneurysms

Brain: Berry aneurysm - arrow

Brain: A large berry aneurysm

Brain: Subarachnoid haemorrhage – ruptured berry aneurysm

Brain: Giant atherosclerotic aneurysm

Haemorrhagic Stroke
Mixed (intraparenchymal and subarachnoid) haemorrhage
A-V malformations Capillary angiomas
Focal irritation may predispose to convulsions (epileptiform attacks)

Brain: Causes of mixed subarachnoid and intracerebral haemorrhages

Brain: Vascular malformations

Brain: Vascular malformation – cerebral hemisphere

Brain: Arterio-venous malformation

Brain: Vascular malformation


								
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