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74 Cards in this Set
- Front
- Back
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does gray or white matter receive more blood flow
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gray matter (3-4x greater)
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2 types of cerebral edema
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vasogenic edema (white matter is exclusively involved); usually from a mass
cytotoxic - involves gray matter and GWJ, usually seen in CVA |
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describe what happens at a cellular level during acute ischemia
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Na-K pump stops working, influx of sodium, efflux of K. Water follows NA and cytotoxic edema results
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timing of insular ribbon sign
situation where this is seen |
within 6 hrs after infarct
MCA occlusion |
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what is the lentiform nucleus edema sign
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early edema in putamen seen in proximal MCA occlusions
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what is the time-frame of T2 hyperintensity in infarct
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6-12 hrs
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what CT findings (other than hemorrhage) are contraindications to TPA
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extensive edema on initial CT (may be associated with increased risk of hemorrhage)
edema affecting >1/3 MCA territory masses |
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what does encephalomalacia mean
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"brain softening"
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pathophys of hemorrhagic transformation of infarction
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reperfusion into infarcted capillary beds can lead to microscopic or gross hemorrhage
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why are pts often asx if they have had a hemorrhagic transformation of infarct
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b/c usually the hemorrhage is in an area of brain that is already dead or dysfxnal
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how to differentiate primary vs secondary hemorrhage
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hemorrhagic infarction is confined to involved vascular territory
primary hemorrhage does not usually respect vascular boundaries intraventricular hemorrhage is uncommon in hemorrhagic transformation petechial gyral pattern is only seen in secondary hemorrhage |
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time-frame of hemorrhagic transformation of acute infarct
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1-2 wks
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how does hemorrhagic transformation of acute infarct usually look
CT MR |
serpiginous line of petechial blood that follows gyral contours of infarcted cortex
on CT: linear hyperattenuating area MR: bright signal along affected gyrus on TI 2/2 methemoglobin |
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what % of stenosis has shown to benefit from CEA
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70% or greater
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in ischemic infarct, what is the first sign of infarct, and how soon can it be seen
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restricted diffusion
within minutes |
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when is maximal intracranial swelling seen after infarct
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3-7 days
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sx of a vertebrobasilar stroke
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syncope
ataxia CN dysfxn homonymous visual field defects facial droop |
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occlusion of what BV --> amaurosis fugax
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ophthalmic branch of ICA
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main branches of ACA
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medial lenticulostriate
pericallosal hemispheric |
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what territory does the medial lenticulostriate artery serve
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rostral portions of BG
(ant/inf internal capsule, putamen, GP, caudate head, portions of hypothal, optic chiasm |
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what is the largest branch of medial lenticulostriate branches
what does it serve |
recurrent artery of Heubner
serves caudate head and anterior internal capsule region |
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sx if there is infarction of medial lenticulostriate territory
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motor aphasia
facial weakness disturbances of mood and judgement |
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what arteries are the hemispheric branches of the ACA
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oribtofrontal and frontopolar arteries
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termination of ACA
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collasomarginal (upper)
pericallosal (lower) this bifurcation occurs just distal to takeoff of the orbitofrontal and frontopolar arteries |
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sx if unilateral damage to ACA hemispheric branches
if b/l? |
leg weakness on opposite side of
body incontinence, akinetic mutism |
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main branches of MCA
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lateral lenticulostriate branches
hemispheric branches |
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pathophys of insular ribbon sign
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when prox MCA is occluded, the insular region is the furthest away from any potential collateral supply
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what do the lateral lenticulostriate branches serve
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putamen
lateral GP superior half of internal capsule and adjacent corona radiata majorityof caudate |
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posteriori hemispheric branches of MCA
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posterior parietal artery (supplies parietal lobe post to sensory strip)
angular artery (post-latl parietal and lateral occipital lobes) posterior temporal artery (majority of temporal lobE) |
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occlusion of what --> broca's aphasia
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anterior MCA branches of dominant hemisphere
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occlusion of what --> wernicke's aphasia
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posterior branches of MCA in dominant hemisphere
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occlusion of what --> contralateral homonymous field defects
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posterior temporal branch of MCA
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what gyrus is involved --> weakness of face, arm, leg
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contralateral precentral gyrus
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occlusion of what --> global aphasia
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total MCA infarct on dominant side
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where does the vertebral artery arise from
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subclavian artery
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at what level of the brain does the basilar artery bifurcate
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midbrain
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major branches of the PC A
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midbrain and thalamic perforating vessels
posterior choroidal arteries cortical branches to medial temporal and occipital lobes |
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sx oifi there is infarction of midbrain
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loss of pupoillary light response (damage to quadrigeminal plate)
impaired upgaze (damage to CN III) somnolence (damage to reticular activating formation) |
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sx in thalamic infarction
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contralateral sensory loss
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what do the posterior choroidal arteries serve
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choroid plexus
pineal gland regions contiguous with 3rd vent |
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what do the PCA cortical branches supply
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inferomedial temp lobe (via the inferior temp artery)
superior occipitalgyrus (par-occ artery) visual cortex and occipital lobe (via calcarine artery) |
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fetal origin of PCA
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20% of pts 'have 1 or both of the prox PCA segments that are hypoplastic or absent
flow instead comes from ICA via a prominent PCOM |
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why does fetal origin of PCA exist
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embryologically, PCA develops with the ICA
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t or f: cbl hemorrhage with any significant mass effect is a surgical emergency
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true --> requires post fossa decompression
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what are the branches of BV to cbl from bottom to top
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PICA
AICA Sup Cbl art |
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what does PICA arise from
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vertebral arteries
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superior cbl artery territory
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superior vermis
middle and superior cbl peduncles "roof" of cbl |
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AICA territory
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ant-med cbl
occassionally part of the middle cbl peduncle |
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PICA territory
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dorsolat medulla
inf vermis posteriolat cbl hemispheres |
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which cbl branch is most commonly infarcted
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PICA
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triggering events for border zone infarct
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cardiac arrest
shock |
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when is unilateral border zone infarct seen
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when carotid occlusion is unmasked by global hypotension
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clinical findings of border zone infarct
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weakness isolated to upper arms
cortical blindness memory loss |
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most common location for venous infarction
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transverse , superior sag sinus, and cavernous sinus
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what are the blood breakdown products
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oxyHb
deoxyHb metHb (intra-, then extracellular) hemosiderin |
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under nml conditions, what state is HB in
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oxygb and deoxyhb
(O2 is extracted from oxy-Hb converting it to deoxy-Hb) |
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what do oxy and deoxy Hb look like on T2
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oxyHb - bright (Fe2+ but in a diamagnetic state)
deoxy-Hb - dark (Fe2+ but in a paramagnetic state) |
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classic presentation of PCOM aneurysm
ICA/parasellar aneurysm Bitemporal field defect |
u/l 3rd nerve palsy
cavernous sinus syndrome ACA aneurysm |
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pathophys of congenital cerebral aneurysm
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congenital absence of arterial media
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size of aneurysm that has increased risk of rupture
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3-5 mm
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most commmon location for aneurysm
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ACOM >
MCA > PCOM > Basilar |
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what should be considered if a distal branch aneurysm is seen
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mycotic aneurysm
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4 main types of vascular malformations
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AVM
cavernous malformation telangiectasia venous malf |
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most comon type of vasc malf
how do they present |
AVM (arteries and veins connected to each other without intervening capillaries)
sz, hemorrhage |
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complications of cerebral AVM
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10% will develop assoc aneurysm
2% annual risk of bleeding |
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histology of cavernous malf
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thin walled sinusoidal vessel (neither artery nor vein)
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presentation of cavernous malf
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sz or small parenchymal hemorrhage
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dva
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congenitally anamolous vein that drains nml brain
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appearance of dva
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enlarged enhancing stellate venous complex that extends to ventricular or cortical surface
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managment of dva
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unclear- they are often the only venous drainage for an area of brain
pts usually asx |
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telangiectasia
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capillary sized vessel, usually small and solitary
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how does amyloid angiopathy often present
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frequently have lobar hemorrhage
can present with progressive senile dementia in 30% pts |
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appearance of amyloid angiopathy
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amyloid deposits in media and adventitia of medium and small BV
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when to think of amyloid angiopathy
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elderly, demented pt with new or recurrent superficial hemorrhage
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