🧠Neurology🧠 - Cerebral Vasculature Flashcards
What are the perfusion demands of the brain?
10-20% of cardiac output
20% of total body oxygen consumption
66% of liver glucos
What do the perfusion demands leave the brain very vulnerable to?
Extremely vulnerable to any impairment of blood supply
What major vessels supply blood to the brain?
Vertebral artery
Common carotid artery - splits into internal and external
Name these 3 vessels
Names these 3 vessels
Name these 2 vessels
Outline the venous drainage of the brain
Cerebral veins -> venous sinuses in the dura mater -> internal jugular veins -> brachiocephalic vein -> superior vena cava
Name these 3 structures
Name these 3 structures
Name these 3 structures
Name these 2 structures
What layer sits immediately deep to the skull?
Dura mater
What are the two layers of the dura mater?
Periosteal and meningeal
Which layer of the dura mater forms structures?
Only the meningeal dura mater folds inwards to form structures, such as the falx cerebri and tentorium cerebelli
Periosteal dura mater stays tightly adhered to the skull
Where do venous sinuses form?
Form in gaps between the two layers of the dura mater
What are the different types of cranial haemorrhage?
Extradural (aka epidural) - skull has no naturally-occurring epidural space, spine does
Subdural
Subarachnoid
Intracerebral
Outline an extradural haemorrhage
Haemorrhage occurs outside the dura
Arterial blood, high pressure (pressure cant escape down the foramen magnum) that can kill quickly
Usually trauma
Immediate clinical effects
Outline a subdural haemorrhage
Haemorrhage occurs within/below dura
Venous blood, lower pressure initially, but can build over time
Usually trauma
Clinical effects can be delayed, but if left can be just as fatal as epidural
Outline a subarachnoid haemorrhage
Haemorrhage occurs usually in the base of the brain - circle of Willis
Ruptured aneurysm
Almost always fatal
Outline an intracerebral haemorrhage
Haemorrhage occurs with cerebral hemispheres
Spontaneous, usually due to hypertensive conditions
Poor prognosis
What is a stroke?
Cerebrovascular accident (CVA)
“rapidly developing focal disturbance of brain function of presumed vascular origin and of >24 hours duration”
Thrombo-embolic (85%) or haemorrhage (15%)
What is a thrombo-embolic stroke?
A blood clot (thrombus) breaks free and travels through the blood stream as an embolus
Reaches the cerebrum, restricting blood flow and causing an ischaemic event
What is a transient ischaemic attack?
a TIA is rapidly developing focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hours
Why should a TIA never go ignored?
Is a sign that someone is at significantly higher risk of developing a cerebral ischaemia, such as a stroke
What is an infarction?
Degenerative changes which occur in tissue (such as cell damage and/or death) following the occlusion of an artery and therefore restriction of blood supply
What is a cerebral ischaemia?
Lack of sufficient blood supply to nervous tissue resulting in permanent damage if blood flow is not restored quickly
What is an embolism?
Plugging of small vessel by material carried from larger vessel e.g. thrombi from the heart or atherosclerotic debris from the internal carotid
What statistics about strokes outline its importance as a public health issue?
3rd commonest cause of death
100,000 deaths in UK per annum
50% of survivors are permanently disabled
70% show an obvious neurological deficit
What is the pneumonic for action when a stroke arises?
F.A.S.T
Face - face fallen on one side, unable to smile
Arms - can they raise both arms and keep them there
Speech - is their speech slurring?
Time - faster response means a better prognosis
What are the risk factors for stroke?
Age
Hypertension
Cardiac disease
Smoking
Diabetes mellitus
Label the cerebral artery perfusion fields
Label the cerebral artery perfusion fields
What are the symptoms of an anterior cerebral artery occlusion?
Paralysis of contralateral structures (leg>arm, face)
Disturbance of intellect, executive function and judgement (abulia)
Loss of appropriate social behaviour
What are the symptoms of middle cerebral artery occlusion?
“Classic stroke”
Contralateral hemiplegia (arm>leg)
Contralateral hemisensory deficits
Hemianopia
Aphasia (if lesion is on L side)
What are the symptoms of posterior cerebral artery occlusion?
Visual defects:
-Homonymous hemianopia
-Visual agnosia
