URR Intracranial Arteries Flashcards
indications for intracranial arteries?
-assess vasospasm/vasoconstriction cause by subarachnoid hemorrhage
-stoke
-TIA
-intracranial stenosis/occlusion
-collateral flow
-AV malformation
-vasospasms
-monitoring for surgery
-shunt detection
-sickle cell anemia for peds
-suspected brain death
limitations of intracranial arteries?
-hyperostosis
-time consuming
-incorrect vessel identification
-vasospasm can be mistake for stenosis
-cannot eval for aneurysm
-patient coooperation
thickening of cranial bones?
hyperstosis
most common type of indication for intracranial artery doppler?
assess vasospasm/vasoconstriction cause by subarachnoid hemorrhage
limitations of TCD?
-inacurate vessel identifcation
-no imaging capabilities
-requires experience
-hyperostosis
what is the transtemporal window used for?
-used to eval MCA, ACA, PCA, and terminal ICA
-patient supine
-notch towards patient nose
in the transtemporal window, how the the MCA flow?
towards the transducer
in the transtemporal window, how does the ACA flow? P1, P2?
away from transducer
-toward
-away
what does the suboccipital (transoccipital) window do?
-evals vertebral and basilar
-patient decub
-probe at the base of the neck and angle cephalad
-basilar flow away from transducer
what does the transorbital (opthalmic) window do?
-evals opthalmic artery and carotid siphon
-patient supine
-output should be at min
-notch should be medially towards the nose
-flow towards the transducer
what does the submandibular window do?
-evals dist ICA and siphon
-flow away from probe
-patient supine
flow velocities normally go how as people age?
decrease
MCA velocities?
10 years old=70 cm/sec
70 years old=41 cm/sec
normal ACA/MCA
<1.2
normal MCA/ICA
1.1-3.0
basilar a / extracranial vert a
<2.0
normal PI
.5-1.1
PI will do what prox to obstruction and what distal to obstrcution?
increase, decrease
difference greater than what in the same vessel on opposite sides indicates disease?
30%
stenosis is most common in what vessels?
MCA, siphon, and terminal ICA
resistnance does what in flow prox to obstrcution?
increase
periorbital doppler?
-CW doppler eval of the frontal artery ( a branch of opthalmic)
-8-10 MHz pencil probe in inner canthus of eye
-normal flow toward the probe
-compression of the infraorbital, facial, and superficial temporal As is performed on both sides while evaling flow
in the periorbital doppler if the flow is away from the probe, what is going on?
obstruction in ipsilat ICA
if compression of 1 artery causes decreased or reversed flow in the frontal artery, that vessel is what?
being used as collateral to fill the frontal artery
-can only determine if there are patent collaterals
-most emerge during fetal development
-headache or seizures
-complications include hemorrhage, cerebral ischemia, cerebral aneurysm, brain damage or stroke
-risk factors include gender (more common in males) and fam hx
intracranial arteriovenous malformations
Large AVM usually identified on fetal US or at birth
vein of galen defect
Unilat vascular AVMs that involve brain, orbits, and facial structures
Wyburn Mason Syndrome
treatment of Intracranial AVMs?
surgical resection, embolization, and radio therapy
complication in patients with subarachnoid hemorrhage, usually slow bleed?
Vasospasm
vasoconstriction of intracranial arteries?
vasospasm
flow velocities in MCA, ACA, PCA usually do what with subarachnoid hemorrhage?
increase
-MCA mean velocity over 200 cm/sec and 120 cm/sec indicates severe reduction
-PI> 1.2 indicates vasospasm
vasospasm usually occurs when during the start of a hemorrhage?
w/in 14 days of the start of the hemorrhage
-record highest mean MCA and terminal ICA
vasospasm can be treated how?
vasodilator
opening in the intercranial septum fails to close after birth
patent foramen ovale
how to look at patent foramen ovale?
-patient supine, performs valsalva
-adjetated saline injected
-microbubbles enter lungs
-if ovale is patent , bubbles will cross into the left heart and enter arch, then cerebrovascular system
if shunt present in patent foramen ovale, what happens?
emboli can be seen in MCA w/in few seconds after injection
-high intensity transient signals (HITS) are vis as bright spikes on doppler
-also may cause “chirping sounds”
if bubbles are seen in the intracranial arteries with foramen ovale?
there must be a right ->left shunt in the heart to send the bubbles into the atrial system
-valsalva may be used to push flow across the PFO into the left atrium
of HITS recorded is directly related to what in the patent foramen ovale?
size of shunt
sickle cell anemia can cause what?
increase PSV in cranial vessels and increase risk of stroke
->200 cm/sec is abnorm for terminal ICA and MCA and indicates increase risk of stroke for children
TCD monitoring during carotid endarterectomy ?
-CA clamed during procedure and ipsilateral MCA evaled
-used to monitor cerebral emboli and to help determine if shunt is necessary
-unilat monitoring of the ipsilat MCA
-if MCA flow present >10 cm/sec after clamping, adequate collat flow is present
TCD monitoring used during open heart surgery with bypass?
used to assess cerebral flow during extracorporal bypass which can lead to hyperfusion of cerebral vessels
-bilat MCA monitoring
-microemboli monitoring
TCD monitoring during ICU monitoring?
-monitor critically ill patients with head issues
-bilat MCA monitoringT
TCD monitoring during brain death?
peaked MCA waveform with moderate flow regversal in diastole
