Cerebral Vasculature and Cerebrovascular disorders Flashcards
why is the brain so very vulnerable if blood supply is impaired?
10-20% of all cardiac output - 20% of all body O2 consumption and 66% of liver glucose despite being only 2% of body weight
what are the main blood supplies for the brain?
vertebral arteries
internal carotid arteries (common carotid)
Circle of Willis
what is the main cerebral branch of the internal carotid artery?
middle cerebral artery
what artery sits on the pons?
basilar artery
what artery connects the posterior cerebral artery and the middle cerebral artery?
posterior communicating artery
what do the vertebral arteries connect to form?
basilar artery
Venous drainage of the brain pathway
Cerebral veins–>dural venous sinuses–>internal jugular vein
where is the confluence of sinuses?
at the base of the occipital bone, medially.
what does the sigmoid sinus eventually become?
internal jugular vein
Meningeal layers
Types of haemorrhage based on meningeal association
What type of haemorrhage is associated with pterion trauma?
Extradural
what is a cerebrovascular accident?
rapidly developing focal disturbance of brain function of presumed vascular origin and of >24hr duration
Two types of stroke
Thrombo-embolic (85%) or haemorrhage (15%)
What is a transient ischaemic attack?
rapidly developing focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hours
what is an infarction?
Degenerative changes which occur in tissue following occlusion of an artery
what is cerebral ischaemia?
lack of sufficient blood supply to nervous tissue resulting in permanent damage if blood flow is not restored quickly
what is a thrombosis?
formation of a blood clot (thrombus)
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 is the difference between embolism and thrombosis?
a thrombosis is a type of embolism (a blood clot that may travel and cause embolism)
Complications of stroke
Permanent disability
Obvious neurological deficit
what are the risk factors for a stroke?
AGE
hypertension
cardiac disease
smoking
diabetes mellitus
what is a perfusion field?
region of the brain a specific vessel is responsible for providing o2 to
what is the perfusion field for the middle cerebral artery?
most of the lateral surface of the cerebral cortex and subcortical deep structures
what is the perfusion field for the anterior cerebral artery?
medial part of cerebral cortex
what is the perfusion field for the posterior cerebral artery?
occipital lobe laterally extending to below the thalamus medially (inferior temporal)
how does an occlusion of the anterior cerebral artery present?
paralysis of contralateral LEG, arm, face
disturbance of intellect, judgement and executive function
loss of appropriate social behaviour
how does an occlusion of the middle cerebral artery present?
classic stroke
contralateral hemiplegia (arm) and hemisensory deficits
hemianopia
aphasia if left sided lesion (because Broca’s/ Wernicke’s)
how does an occlusion of the posterior cerebral artery present?
visual defects - homonymous hemianopia, visual agnosia
path of venous drainage of the brain
inferior/superior sagittal sinus –> confluence of sinuses –> Great cerebral vein –> straight sinus –> confluence of sinuses –> Transverse sinus –> sigmoid sinus –> jugular foramen–> internal jugular vein
What major risk factor for stroke is evident in this specimen?
The yellow discolouration in the walls of the vessels is a build-up of atheroma, fatty deposits that cause atherosclerosis or“hardening of the arteries”
Which cerebral artery has been occluded in this specimen?
The marked area shows
evidence of infarction in the
perfusion field of the right
middle cerebral artery
