cerebral vasculature Flashcards
What are the main 2 artery sets that supply the brain and where do they go?
Internal carotid arteries and vertebral arteries. Internal carotid divides from common carotid artery at level of adam’s apple in order to supply the brain. The vertebral arteries go up posteriorly through cervical vertebrae transverse foramens
If blockage in one of the internal carotids what could possibly happen? What are the problems with that?
could have compensatory blood flow from communicating arteries of the circle of willis however this is not universal and can be variable due to thinness of communicating arteries.
What is the venous drainage of the brain?
Brain drains by cerebral veins into dural sinuses into the internal jugular veins and back to heart.
What are the dural folds passing between 2 hemispheres? In cerebellum?
Falx cerebri and falx cerebelli
What is pattern of drainage of venous sinuses? Of the brain itself?
Superior sagittal sinus above, inferior sagittal sinus below -> drain into confluence of sinuses. Brain itself by vein of galen - great cerebral vein - into straight sinus to confluence of sinuses and then through transverse sinus to sigmoid sinus and through jugular foramen.
What is an intracranial haemorrhage?
Haemorrhage inside cranial cavity itself.
What are the dural layers of the brain?
Dura mater (periosteal & meningeal), arachnoid matter, subarachnoid space under, pia mater
What happens during an extradural bleed? How does it present and what must be done?
Trauma (especially to weak spot of pterion) causes damage of the middle meningeal arteries that supply dura - rupture and bleed stripping the dura matter from the skull and causing large arterial bleed - quick symptoms and need surgery. bleed in potential area between skull and periosteal (doesnt exist usually)
What happens during a subdural haemorrhage? How does it present and why?
Subdural haemorrhage occurs in the space between dura and arachnoid matter - largely due to trauma but with delayed symptoms because the blood is venous. Symptoms can present hours/days later.
What happens during a subarachnoid bleed and when can this happen?
Usually at base of brain (circle of willis) and aneurysms (weaknesses of blood vessel walls form), congenital mainly. In hypertension these can bleed and cause subarachnoid bleed.
What happens during an intracerebral bleed and when can this happen?
Bleed in brain itself. Usually spontaneous hypertensive - chronic raised hypertension.
What is a stroke or cerebrovascular accident? What are the most common causes?
Rapidly developing focal disturbance of brain function due to presumed vascular origin of more than 24 hours duration. Usually most are thromboembolic but some can be haemorrhage (mainly sub-arachnoid).
What is a transient ischaemic attack TIA? What is it a warning of? How long does it last?
Rapidly developing focal disturbance of brain function due to presumed vascular origin that resolves completely within 24 hours. Can last minutes or seconds. Warning sign of subsequent strokes
What is infarction?
Degenerative changes occuring in tissues due to occlusion of artery (loss of blood supply)
What is cerebral ischaemia?
Lack of blood supply to nervous tissue causing permanent damage if not resolved.
What is thrombosis?
Formation of blood clot
What is embolism?
Occlusion of small vessel due to material originating from larger vessel eg. Blood clot or atherosclerotic debris
What are the key symptoms of stroke? What to do?
Face fallen on one side, paralysis on one side, speech changes. Call 999
What are risk factors for stroke?
Hypertension, high cholesterol, cardiac disease, smoking, diabetes
What do each of the cerebral arteries supply?
Middle cerebral artery biggest perfusion field, most of brain and subcortical deep structures. Anterior cerebral artery mainly midline structures up to posterior fissure. Posterior artery mainly occipital lobe and inferior part of temporal lobe.
What are symptoms of anterior cerebral artery stroke?
Contralateral paralysis of structures (leg > arms). Frontal lobe - disturbed intellect, executive function, judgement (abulia), social behaviour)
What are symptoms of middle cerebral artery stroke?
Classic stroke, contralateral hemiplegia (arms> legs), contralateral hemisensory deficits, hemianopia if visual system affected, aphasia - speech problem (l sided).
What are symptoms of posterior cerebral artery stroke?
visual loss (homonymous hemianopia). Visual agnosia & prosopagnosia.
