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Cerebrovascular Disease. FM Brett , MD, FRCPath. ~ In USA 0.5 million new strokes diagnosed annually and 3 million survivors of a previous stroke. ~ Stroke 3 rd most frequent cause of death ~ 2 nd most frequent cause of dementia ~ Major reason for severe disability and long term

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cerebrovascular disease
Cerebrovascular Disease

FM Brett , MD, FRCPath

slide2

~ In USA 0.5 million new strokes diagnosed annually and 3 million survivors of a previous stroke

~ Stroke 3rd most frequent cause of death

~ 2nd most frequent cause of dementia

~ Major reason for severe disability and long term

dependency

slide3

Epidemiological aspects of stroke

~ In the USA stroke is the third commonest cause

of death

~ Incidence increases with age

~ Major risk factors for stroke are hypertension,

cardiac disease, smoking, hyperlipidemia, and diabetes

~ Other causes OCP, sickle cell, coagulation disorders

~ In USA - brain infarction 10 times commoner than haemorrhage

slide4

Blood supply to the brain

~ Human brain approx 2% of body

weight

~ Receives 15% of total cardiac output O2 consumption approximately 20% of whole body (i.e high metabolic rate)

~ How long would the brain survive if blood flow interrupted

slide6

Terminology

~ Ischaemia - arterial stenosis or occlusion

Infarction - perfusion territory of the affected vessel

~ Global brain ischaemia - < CPP below the threshold for autoregulation i.e when systemic blood pressure falls very low e.g cardiac tamponade, heroin overdose, or ICP rises to a level that compromises cerebral perfusion

Resultant brain damage or infarction is accentuated in the

WATERSHED REGIONS

slide8

CPP= SAP - ICP

CPP > 40 mmHg - necessary for autoregulation

If CPP < 40 mmHg CBF falls dramatically

slide9

Principal causes of hypoxia

Hypoxemic hypoxia - low O2 in blood

~ Carbon monoxide poisoning

~ Near drowning

~ Respiratory arrest

~ Prolonged status epilepticus

Stagnant hypoxia - (inadequate supply of oxygenated O2

~ Cardiac arrest

~ Rise ICP

~ Respirator brain

Histotoxic hypoxia (inability of tissues to use O2)

~ Cyanide and sulphide exposure - inhibition of mitochondrial

enzymes involved in oxidative respiration

slide10

Selectively vulnerable zones

~ Hippocampus - CA1

~ Laminae 3 and 5 of cortex

~ Purkinje cells cerebellum

slide12

HYPOXIA- blood flow to the CNS may be normal or increased

Damage occurs in selectively vulnerable neurones

slide13

Hypoxic ischaemic encephalopathy

~ Variable clinical presentation

~ Clinical recovery generally better after hypoxemic

hypoxia than after global brain ischaemia

~ Severity and duration of HIE after transient cerebral

hypoxia depends on

I) duration of insult

2) completeness of insult

3) blood glucose level (high level poor outcome)

4) CNS temperature

~ Long term sequelae - difficult to predict

slide16

Infarct - region of cell death

Infarct may become secondarily haemorrhagic and may mimic a

primary haemorrhage

STROKE - rapid onset of focal disturbance of cerebral function

lasting > 24 hours

TIA - less than 24 hours

Infarcts may be caused by:

~ Large vessel or macrovasculature disease

~ Small vessel or microvasculature disease

~ Emboli

~ Venous thrombosis

slide17

Types of vascular disease

Anterior circulation

A. Small vessel disease – e.g microangiopathy

B. Occlusive large vessel disease of pial arteries

C. Occlusive large- vessel disease of brain supplying arteries in the neck

D. Embolising heart disease including aortic plaques

and R-L shunts

slide18

1 a, b – small vessel disease

2 a,b. Atherosclerotic or

embolic occlusion of

cerebellar artery

3 – intracranial thrombosis

4 – atheromatosis of

vertebro-basilar artery

5 – embolus sticking in

mid-basilar artery

  • In situ thrombosis of
  • basilar artery
slide20

Thalamic infarction

Sensory or sensiomotor hemi-deficits with disassociated

sensory loss, hemispasticity or even severe impairment of position sense;

Segmental and focal dystonia without jerks and abnormal dystonic posture of affected hand

slide23

~ Large vessel disease includes atherosclerosis,

fibromuscular dysplasia,

arterial dissection,

giant cell arteritis

ATHEROSCLEROSIS IS THE COMMONEST OF THESE

slide26

ATHEROSCLEROSIS - leading vasculopathy

producing brain infarcts. Affects intracranial and

extracranial large vessels

RISK FACTORS

~ Hyperlipidemia

~ Hypertension

~ Cigarette smoking

~ Obesity

~ Age

~ Sex

pacns

Small vessel disease includes cerebral vasulitides

PACNS

~ Isolated granulomatous or primary angiitis of the CNS (PACNS)

slide30

PACNS

~ Recognised in the mid 1950’s

~ Diagnosis:

~ Clinical

~ Imaging

~ Biopsy

slide33

EMBOLIC DISEASE

  • Embolic stroke results when any solid material:
  • forms within the aterial circulation
  • is introduced into the arterial circulation
  • forms within the venous and has a conduit to the
  • arterial circulation ì.e right to left shunt
  • Resultant infarct is :
  • clinically abrupt
  • haemorrhagic
slide35

Autopsy of a stroke patient

If infarction

1. Examine major cranial arteries i.e

carotid and vertebral arteries in the neck

2. Carefully examine heart for:

infective endocarditis

valvular abnormalities

septal defects

slide36

IF haemorrhage

Look for evidence of:

1. Hypertension i.e cardiomegaly, LVH, nephrosclerosis

2. Neoplasia

3. Drug abuse

4. If dementia CAA

slide37

Blood in the cranial cavity

  • Source?
  • Spread
  • Occur?
  • Cause?
  • Sufficient to cause death
slide38

Intracranial haemorrhage

  • Extradural
  • Subdural
  • Subarachnoid
  • Intracerebral
slide39

SAH

  • Berry aneurysm
  • Infectious
  • Fusiform aneurysm
  • AVM
  • CAA
slide41

Berry aneurysms

  • Congenital
  • Risk of bleeding inc;
  • Hypertension
  • AVM
  • systemic vascular
  • disease
  • defects collagen
  • polcystic renal disease
slide42

ICH causes

  • Hypertension
  • Trauma
  • CAA
  • Berry aneurysm
  • AVM
  • Bleeding diathesis
  • Vasculitides
  • Drugs
  • Neoplasm
  • Infective
slide43

Hypertension - major risk factor for brain haemorrhage

  • Occurs due to rupture of arterioles that have become
  • weakened
  • DUE TO
  • Replacement of smooth muscle by fibrocartilagenous material
  • Fragmentation of elastic tissue
  • Charcot-Bouchard aneurysms
slide44

Haemorrhages involving the basal ganglia-

putamen in particular

tend to be non-traumatic and caused by

hypertension

slide45

Chronic hypertension

leads to arteriolar sclerosis

resulting in small lacunar

infarcts

OCCUR~ BASAL GANGLIA~ PONS~ DEEP WHITE

MATTER

slide46

AVM

  • Commonest 3-4th decade
  • Rarely familial
  • Rarely multiple
  • have a nidus
  • commonest vascular malformation
  • identified in surgical specimens
slide49

Venous Thrombosis

~ Often secondary to infectious causes

~ Pregnancy

~ Puerperium

~ OCP

~ Haematological abnormalities