Cerebral Infarcts (Stroke) Flashcards
How well do people recover from strokes?
50% of survivors become dependant on others for daily activities
& roughly 1/3rd die within a yr
Strokes are Sudden onset focal or global neurological deficit due to ischaemia or haemorrhage lasting >24 hours
Irreversible Ischaemia causing infarction (Tissue death)
TIAs last <24 hours (most resolve in minutes)
Reversible ischaemia with still viable tissue
Common causes of stroke?
Ischaemic (85%):
- Large Artery Atherosclerosis 35%
- Cardioembolic e.g. af 25%
- Small artery occlusion (Lacunar stroke)
- Rarely venous sinus thrombosis or arterial dissection
Haemorrhagic:
- Primary Intracererbal Haemorrhage 70%
- Secondary Haemorrhage e.g. SAH (Anuerysm) or Arteriovenous malformations
What test is done when someones rushed in with a stroke?
A CT brain
Shows up infarcts, bleeding etc quite well
(Can also do an MRI when you have time)
How is the incidence of stroke changing?
The incidence is decreasing but the total number is increasing due to the aging population
Describe the pathophysiology of stroke:
- Cerebral blood flow fails to reach a part of the brain
> Hypoxia
> Hypoxia stresses the brains metabolism (Especially in ischaemic penumbra) and leads to anoxia if prolonged
-> Anoxia -> Infarction (Cell death)
-> Necrosis
Further damage can occur due to oedema or secondary haemorrhage
What is the ischaemic penumbra?
Region around the edge of the ischaemic core, because blood & o2 supply is reduced locally after an ischaemic event
The tissue may remain viable for several hours due to collateral circulation.
Risk factors for stroke?
Non-Modifiable:
- Previous stroke
- Age
- Male
- Family history
- Diabetes
Modifiable: - Hypertension - Smoking - Hypercholesterolaemia - Diet - Sedentary lifestyle - High BMI (obesity) - Alcohol - Raised Oestrogen (e.g. HRT or OCP) -
how is hypertension a risk factor?
- Worsens atheroma
- Damages small arteries (Least muscular and least likely to handle high pressures)
- Increases risk of aneurysm and bursting so a major risk factor in haemorrhagic stroke
Describe the common pathology of small vessel disease?
Small Artery Lipohyalinosis
Hypertension caused thickening of small artery walls leading to luminal narrowing
How does diabetes affect stroke?
Increases risk up to 3fold
How do lipids affect stroke risk?
- Increases Atheroma
How does smoking affect stroke risk?
doubles risk of stroke
triples risk of SAH
some of the increased risk relates to cardiac problems smoking predisposes you to
How does alcohol affect stroke risk?
Small amounts actually decrease risk but heavy drinking more than doubles it
How does obesity affect stroke risk?
Independant risk factor, particularly abdominal obesity
Here are some more risk factors
- High oestrogen e.g. HRT or OCP
- Impaired cardiac function such as AF or recent MI
- Hyper-coagulable states either genetic or malignant
What are borderzone anatomoses?
Anastomoses between peripheral branches of cerebral arteries
too small to compensate for blocked major arteries
Symptoms specific to Ant Cerebral Artery occlusion?
Affects frontal and parietal lobes, mainly at the inside/top:
- Paralysis of foot/leg
- Sensory loss of foot/leg
- Impairment of gait/stance
(Remember affects the top of the motor/sensory cortexes, this is where the homunculusses have foot/leg fibres)
Symptoms specific to Middle Cerebral Artery?
- Paralysis of face/arm/leg
- Sensory Disturbance to Face/arm/leg
- Homonymous Hemianopia
- Gaze paralysis to opposite side/Deviation to affected side
- Aphasia if on dominant side (Wernicke’s and/or Broca’s)
- Unilateral neglect and agnosia for contralateral half the external space
What neglect syndromes result from right hemisphere damage?
- Visual Agnosia (Cant process left side vision)
- Sensory Agnosia
- Anosagnosia (Denial/unawareness of hemiplegia or stroke as a whole)
- Prosopagnosia (Failure to recognise faces
Which cerebral artery supplies the basal ganglia?
Middle cerebral -> Lenticulostriate arteries
Whats distinct about lacunar stroke syndrome?
No cortical signs (Dysphasia, neglect etc)
Just pure motor or pure sensory
What does the basilar artery supply?
Brainstem, Cerebellum, thalamus
Where does the post cerebral circulation supply?
Brainstem. cerebellum and thalamus
+ Occipital and medial temporal lobes
