stroke what is and causes Flashcards
how common is stroke
1 in 4 people worldwide, third biggest killer in Scotland, one stroke every 5 mins in uk, 1 in 8 patients die within 30 days
what is a stroke
loss of neurological function of sudden onset, lasting more than 24 hours and of vascular origin
transient ischaemic attack
lasts less than 24 hours
how is stroke caused
blocked vessel with thrombus or clot in the brain, disease of vessel wall, disturbance of normal properties of blood, ruptured vessel wall, 85%-90% infarction, 10-15% haemorrhage
how does ischaemia cause stroke
clot stops blood supply to an area of the brain
how does haemorrhage cause stroke
blood leaks into brain tissue
what diseases cause stroke
large artery- carotid stenosis, intracranial stenosis, cardioembolic stroke, small vessel disease (lacunar stroke)
carotid disease
a lot of turbulence in area of bifurcation of the carotid arteries. atheroma occurs here. of the plaque ruptures tiny pieces of plaque and clotted blood can travel in the bloodstream to the brain
cardioembolic stroke
caused by atrial fibrillation, clot forms in left atrial appendage then blood breaks of from heart up into the aorta and then up into cerebral vessels and this will lead to some occlusion of vessel and dead tissue on a penumbra surrounding the area of the occluded vessel. tissue dies or stops functioning properly due to lack of oxygen and glucose. over first 24 to 36 hours after stroke the penumbra gradually dies off. some blood supply will be restored and tissue will survive and the remaining sleeping tissue dies
small vessel disease (lacunar stroke)
large vessels like the middle cerebral artery have tiny branches going off deep into brain tissue. one of these lenticulostraite arteries occludes and affects a small area of break. small leak in brain. associated with hypertension and thinking of the walls of these tiny vessels making the lumen smaller
rare causes of stroke
carotid dissection
carotid dissection
causes large vessel stroke, lining of blood vessel tears and thrombus forms above that and then the thrombus may head off into the brain and cause a stroke. rock tail appearance on angiogram. usually associated with trauma of some kind