Cerebrovascular Review Ch. 18,19, 22 Flashcards
anterior circulation: ICA
distributes blood to the anterior brain, the eyes, forehead, nose
ICA branches
ophthalmic artery, anterior cerebral artery, middle cerebral artery
Majority of the blood in the ICA
70-80% flows from the common carotid artery
carotid siphon
a significant curve of the distal ICA
ECA branches
superior thyroid artery, ascending pharyngeal a., lingual a., facial a., occipital a., posterior auricular a., superficial temporal a., and maxillary a.
anterior circulation: ECA supplies blood to
neck, face, scalp
posterior circulation
rt. and left vertebral arteries, basiliar artery, and circle of willis
periorbital circulation
branches of the ophthalmic artery- supraorbital artery, frontal artery, and nasal artery
Supraorbital artery (from ICA to ECA)
ICA-ophthalmic a.-supraorbital a- superficial temporal a.- ECA
Frontal artery (from ICA to ECA)
ICA- ophthalmic a. - frontal a.- superficial temporal a.- ECA
Nasal artery (from ICA to ECA)
ICA- ophthalmic a. - frontal a. - nasal a. - angular a.- facial a. - ECA
Tunica intima
inner layer of a vessel
a single layer of endothelial cells with a base membrane and connective tissue
tunica media
middle layer of a vessel
thick layer of smooth muscles and collagenous fiber
tunica adventitia
a thin fibrous layer of connective tissue and some smooth muscle fibers
contains the vasa vasorum
vasa vasorum
supplies blood to the walls of the larger arteries
transports oxygen and nutrients as well as removing waste products
Q= (P) * r^4 / 8nL
Relationship of flow vs. pressure gradient and size of the vessel
flow is directly proportional to pressure gradient and size of the vessel
flow vs. viscosity and length of a vessel
flow is inversely proportional to viscosity and length of a vessel
velocity and energy losses
velocity increases at a stenosis
this acceleration increases energy losses
turbulence is detected by
spectral broadening which is a wide range of very low to very high frequency shifts
TIA
transient ischemic attack, a fleeting neurologic dysfunction without lasting effects, symptoms do not last more than 24 hours
RIND
reversible ischemic neurologic deficit, lasts longer than a TIA but resolves in time
VBI
vertebrobasilar insufficiency, usually causes bilateral visual blurring or paresthesia and complaints of vertigo, ataxia and drop attacks
CVA
cerebrovascular accident, produces a permanent neurologic deficit
Risk factors for cerebrovascular disease
diabetes mellitus, hypertension, smoking and hyperlipidemia
most common mechanisms of cerebrovascular insufficiency
ischemia and hemorrhage
three leading causes of ischemia
atherothrombotic pathology, cardiogenic, and lacunar strokes
atherothrombotic pathologies
alterations in perfusion secondary to an atheromatous plaque resulting in stenosis, occlusion, or thromboembolic event
cardiogenic pathologies
usually responsible for cerebrovascular ischemia are altered cardiac function and most often an embolism
lacunar strokes/ infarction
a small circumscribed loss of brain tissue caused by an occlusion of one of the small penetrating arteries in the brain
the second most common mechanism of cerebrovascular insufficiency
hemorrhage, may be the result of hypertension, ruptured aneurysm, or trauma
fatty streak
a thin layer of lipid material on the intimal layer of the artery
fibrous plaque
an accumulation of lipids that is covered by more lipid material, collagen, and elastic fiber deposits
complicated lesion
fibrous plaque that contains fibrous tissue, more collagen, calcium, and cellular debris
ulcerative lesion
deterioration of the normally smooth surface of the fibrous cap
embolism
a foreign substance or piece of a thrombus that moves through the circulatory system until it lodges in a distant blood vessel
source of an embolism
heart, atherosclerotic plaque
Thrombosis
composed of platelets trapped within a network of fibrin, one of the most common causes of a stroke
aneurysm
an abnormal localized dilatation of a blood vessel due to congenital defects or weakness of the vessel wall
cerebrovascular signs and symptoms
affected artery: ICA
contralateral weakness, paralysis, numbness, and or sensory changes; ipsilateral amaurosis fugax and or a bruit, may have aphasia if in the dominant hemisphere, occasionally altered level of consciousness
cerebrovascular signs and symptoms
affected artery: middle cerebral
aphasia or dysphasia, severe contralateral hemiparesis or hemiplegia (more severe in face and arm rather than leg if upper division MCA occluded) dysarthria, behavioral changes, confusional state, agitated delirium ( if lower division MCA occluded)
cerebrovascular signs and symptoms
affected artery: anterior cerebral
contralateral hemiparesis (especially in leg) incontinence, loss of coordination, impaired motor and sensory functions
cerebrovascular signs and symptoms
affected artery: vertebrobasilar
numbness around lips and mouth, diplopia, poor coordination, dysphagia, vertigo, amnesia and ataxia
cerebrovascular signs and symptoms
affected artery: posterior cerebral
dyslexia, coma (paralysis usually absent)
