Cerebrovascular disease Flashcards
define a transient Ischemic attack
sudden, focal neurological deficits which completely resolve within 24 hours
are a serious warning of stroke risk
what is the most common cause of a stroke
ischemic infarction
what are stroke risk factors
atherosclerosis risk factors - hypertension, heart disease, diabetes, smoking, hyperlipidemia and a family history of vascular heart disease
where do atherosclerotic changes predominate
at the bifurcation points of large major cervical and intracranial arteries (more turbulent flow)
what are the 2 mechanisms of ischemic infarction
- local arterial thrombosis of an atheroma
2. embolic arterial occlusions from a proximal source
what is the most important factor in determining whether a patient is able to create collateral blood flow
a complete circle of willis
describe how a patient may have an asymptomatic occlusion of a cervical internal carotid artery
if a thrombosis is formed gradually, other arteries may detour blood flow to the potentially ischemic areas of the brain
how does a large artery infarction appear pathologically
the cerebral cortex will appear soft and swollen with less distinction of the gray-white matter junction and spotty hyperemia
microscopically 12-36 hours after a stroke how does the brain appear
ischemic neurons shrink and appear eosinophilic (“pink neurons”)
what is seen microscopically days after a stroke
macrophages scavenge necrotic debris and cyst formation occurs with astrocytes at the periphery of the infarction
what causes lacunar infarcts
thrombosis (not emboli)
what is a lacunar infarct
a small lesion of a perforator or lenticulostriate artery which are small branches from larger arteries that supply the deep structures of the brain
why are lacunar infarcts significant
they typically occur in the basal ganglia, internal capsule, thalamus and corona radiata- areas with complex and important functions so even a couple mm lesion can cause serious neurological deficits
what is amaurosis fugax
monocular blindness - one type of carotid territory TIA . Pt describes a lowered dark shade in one eye which gradually lightens up
what types of symptoms do vertebrobasilar territory TIAs cause
ataxia, homonymous hemianopsia, or hemiparesis associated with crossed brainstem syndromes
vertebrobasilar territory TIAs cause ischemia of what areas
brain stem. cerebellum, visual (occipital) cortex
carotid TIAs produce symptoms of
hemispheral ischemia leading to hemiparesis or aphasia
where does a hemiparesis with greater weakness of the face and upper limb suggest the location is
the precentral middle cerebral artery territory
where does a hemiparesis with great weakness of the lower limb suggest the location is
precentral anterior cerebral artery territory
where does sensory deficits limited to the face and upper limb suggest the infarct is
postcentral MCA
where does sensory deficits limited to the lower limb suggest an infarct is located
postcentral ACA
what kind of stroke is suggested by pure motor hemiplegia, ataxic-hemiparesis and clumsy hand-dysarthria
a lacunar stroke of the internal capsule, corona radiata or basilar pons
a pure sensory stroke is indicated of what type of stroke
a lacunar syndrome from a small vessel occlusion involving the thalamus
what is an atheroma
(arterial plaques) form from subintimal lipid deposition, smooth muscle proliferation & fibrosis.
how do atheromas lead to stroke
Bulging atheromas or plaques can narrow or occlude the arterial lumen (thrombosis), or ulcerate and travel downstream (embolize).
what are possible cardiac sources of an embolis
MI
A. fib
valvular lesion
R to L shunt (patent forman ovale)
what are some hypercoaguable states that may contributed to a stroke
sickle cell anemia, polycythemia vera, vasoactive recreational drugs (cocaine)
what other pathologies must be ruled out when a stroke is suspected
atypical presentation of tumor, hemorrhage, abscess, or encephalitis
what is used to confirm the diagnosis of a stroke
MRI (CT is second best)
should a source of embolism be looked for in a lacunar stroke
no - it is unlikely that an embolism would cause a lacunar stroke. they are typically thrombotic
what is a carotid endarterectomy
the surgical removal of an atheromatous lesion
when should a carotid endarterectomy be done
in patients with symptomatic lesions of 70-99% blockage at the origin of the internal carotid artery
if carotid endarterectomy is not option what other treatments are available
stenting and angioplasty
within what time frame should tPA be adminstered
within 3 hours of stroke onset
what are the symptoms of a cerebral hemorrhage
severe headache, early impairment of consciousness (atypical for infarction)
what is the cause of death in a severe hemorrhage
shifting or herniation of the brain
what is the best imaging to identify a bleed
CT - blood is white
what is the most common cause of cerebral hemorrhage
Hypertension
weakened walls of small, penetrating arterioles rupture. Typical bleeding sites: basal ganglia and thalamus
what are causes of cerebral hemorrhage
hypertension
head trauma
rupture of congenitally abnormal blood vessels
bleeding within an ischemic infarction or tumor
systemic bleeding gidsorders
illicit drugs (via hypertension)
cerebral amyloid angiopathy (elderly patients)
what’s the most common cause of a subarchnoid hemorrhage (SAH)
trauma
what is a berry aneurysm
- thinned out pouchings at intracranial arterial bifurcations
- may enlarge over time with increased risk of rupture
what is the most common location for a Berry aneurysm
the anterior circle of willis
what is berry aneurysm syndromes
- asymptomatic
- warning leak - worst head of my life w/ meningeal signs
- mass effect (CN III palsy)
- massive, fatal SAH
how would you evaluate symptomatic berry aneurysms
- CT brain scan
- lumbar puncture (if CT is normal to verify SAH)
- cerebral angiogram
- emergent clipping or endovascular coiling of aneurysm
