Pathology of Cerebra-Vascular Disease Flashcards
Describe the venous drainage of the brain
Veins do not accompany arteries
Large venous sinuses within dura
Fed by bridging veins from brain which cross the meninges to the skull
Emissary veins link to veins outside the skull
What is a stroke?
Focal neurological deficit (loss of function affecting a specific region of the central nervous system) due to disruption of its blood supply.
How do most strokes occur?
Blood vessel being blocked by a thrombus (ischaemic stroke)
Around 1 in 10 strokes arise from a ruptures blood vessel causing a haemorrhage
What are the major features of stroke?
Focal neurological deficit:
- Sudden weakness or numbness
- face, arm or leg, most often on one side of the body
Others:
- Confusion, difficulty speaking/ understanding speech
- Difficulty seeing (one or both eyes)
- Difficulty walking, dizziness, balance/ coordination loss
- Severe headache with no known cause
- Unconsciousness
What is a transient ischaemic attack (TIA)?
Symptoms and signs last
What is a minor stroke?
> 24 hours but minor neurological deficit
What is a disabling stroke?
> 24 hours with persisting disability that impairs independence
How much cardiac output provides cerebral blood flow?
15%
How long does hypoxia or anoxia take to cause brain ischaemia?
Few minutes
What can ischaemia cause?
Can lead to infarction
Damage to neurones is permanent
Neurones do not regenerate
Why is neuronal plasticity important in the recovary from stroke?
Through physiotherapy, speech theraoy etc we can train other neurones to do the job of the ones that are lost
What is ischaemia?
Relative or absolute lack of oxygen in a tissue or organ
What is infarction?
Regional cell death
Briefly run over virchow’s triad
Change in vessel wall, flow, content
What are some of the causes of CNS ischaemia?
Atherosclerosis
Thrombosis
Embolism
-Arterial thromboembolism, fat)
Hypotension
- Cardiac arrest
- Massive blood loss
Arterial spasm following subarachnoid haemorrhage
Systemic vascular disease
-e.g. arteritis
Mechanical compression
- Head injury-> brain swell
- Tentorial herniation
- Spinal cord compression
Venous obstruction
- Mediastinal tumour
- Dural vein thrombosis (sepsis)
How does the infarction of neurones compare to glial cells?
Neurones die fast
Supportive (glial) tissues are more robust
What may cause global ischaemia?
Systemic hypotension
What MAP puts the patient at risk of systemic hypotension?
MAP less than 60mmHg
What neurones are particularly at risk in global ischaemia?
Superficial cortex
Hippocampus
Thalamus
Cerebellum
What is the normal histology in a CNS infarct?
Loss of neurones
-causes clinical functional deficit
Foamy macrophages
-repair process leasing to gliosis
Gliosis = CNS equivalent of fibrosis
What is haemorrhagic stroke?
Rupture of a small artery usually at a bifurcation leading to catastrophic haemorrhage
about 15% of strokes
Describe intracerebral haemorrhage
Associated with systemic hypertension in over 50s
80% of these in basal ganglia
Also occur in brainstem, cerebellum, cerebral cortex (decreasing order)
What causes the damage in haemorrhagic stroke?
Rapidly growing intracranial space occupying lesion and increased ICP
What is a subarachnoid haemorrhage?
Rupture of saccular (Berry) aneurysm on circle of Willis
What is a common presentation for interventrcular haemorrhage?
Hypoxia in premature infants
Babies in NICU
Poor outcome
What are the consequences of intracranial haemorrhage?
Death because of rapid increase in ICP (esp subarachnoid)
Clinical features of stroke (headache esp in SAH)
Secondary infarction
-Local effect of mass lesion and ICP effect
Long term survivors lose brain tissue - cystic
