Stroke (3) Flashcards
Stroke
Sudden onset, focal neurological deficit of vascular origin, symptoms last over 24 hours/death
Sir Godfrey Hounsfield
X-ray computed tomography
What percentage of strokes are caused by infarction?
85%
What percentage of strokes are caused by haemorrhage?
15%
Acute ischaemic stroke
Initial reduction in cerebral blood flow > ischaemia > alterations in cellular chemistry > cellular necrosis
Cerebral blood flow
50-55ml/100g
Average brain weighs
1400g (2% body weight)
Average Cerebral Blood Flow
800ml/min (15% cardiac output)
Whole brain oxygen consumption (CMRO2)
3.3-3.5ml/100g/min
45ml O2/min
20% total body O2 consumption at rest
Flow =
pressure/resistance
CPP
Cerebral perfusion pressure
CVR
Cerebrovascular resistance
CBV
Cerebral blood volume
OEF
Oxygen extraction fraction (30% normally)
PaCO2
1mmHg rise > 3-5% increase in CBF
Viscosity
Normally mainly haematocrit
What is the sole substrate for energy metabolism in the cerebrum?
Glucose (75-100mg/min or 125g/day)
Glucose is metabolised by the … sequence and the … cycle
glycolytic sequence and the tricarboxylic acid cycle
Neurones require a constant supply of ATP, why?
To maintain integrity (K+ inside, Na+ and Ca2+ outside), cannot be stored
Glycolysis
1M glucose > 2M pyruvate (generates 2M ATP in process)
Aerobic
Pyruvate > CO2 and H20 + 36 ATP
Anaerobic
Pyruvate > lactate + 2M ATP
What causes ischaemic stroke?
Athero-thrombo-embolism
Thrombosis (extra-cranial/intra-cranial)
Embolism (cardiogenic/artery to artery)
Atrial Fibrillation
Treatment
Thrombolysis, early recanalisation or stentrivers
Which vessel occlusion accounts for 18-25% of all ischaemic stroke but 60-70% of deaths/severe disability?
Proximal anterior circualtion large vessel occlusion (ICA/M1)
Stentrievers
Stents reperfuse brain, leave for 10 mins, withdraw stent with smaller clot ‘core’
