6/10- Cerebrovascular Anatomy Flashcards
(40 cards)
What is a stroke?
Damage to the brain due to vascular causes; interruption of blood flow in a cerebral vessel
What are the 2 different types of strokes?
- Ischemic (decreased flow)
- Hemorrhagic
Cerebrovascular disease tends to produce ____ (gradual/rapid), ____ (focal/generalized) neurologic deficit
Cerebrovascular disease tends to produce rapid, focal neurologic deficit
What is the main source for anterior circulation?
What areas does this cover?
Internal carotid arteries
Most of cerebral hemispheres
- Cortex
- White matter
- Diencephalic structures
What is the main source for posterior circulation?
What areas does this cover?
Vertebral arteries
- Brainstem
- Cerebellum
- Occipital
- Mesial temporal lobe
What connects the anterior and posterior circulation?
Posterior communicating arteries
(provide collateral circulation; variable amounts)
Picture of vasculature
Dotted lines = Circle of Willis
FACTS:
- Vertebral arteries ascend in bony cervical vertebrae
- PICA come off single vertebral a’s
- Vertebral a’s joint to form basilar a.
- Basilar branches = AICA and SCA before it terminates as PCA
- Smaller basilar branches = Labyrinthine (internal auditory) a, pontine arteries (variable)
- Post communicating comes off PCA to connect into internal carotids
- Internal carotids give off MCA and ACA (connected by ant communicating)
- Smaller carotid branch = ophthalmic a.
- Branches off MCA = anterior choroidal a, lenticulostriate a’s
- Branches off ACA = medial striate a. (Recurrent a. of Heubner)
What provides circulation to the brainstem?
- Medial arteries (midline parts of medulla, pons, and midbrain)
- Lateral arteries (lateral parts of medulla, pons, and midbrain)
What provides circulation to the cerebellum? Defects from occlusion?
- Posterior and anterior inferior arteries supply inferior cerebellum
- Superior cerebellar a. supplies superior cerebellum
Defects: Ipsilateral ataxia/hypotonia
What does posterior cerebral artery supply?
Defects from occlusion?
- Occipital lobe: visual field defect/complex visual agnosia
- Inferior medial temporal lobe: defects in recognition of things and people (prosopagnosia- facial recognition)
What is the most common stroke of posterior circulation?
Lateral medullary infarct (Wallenberg syndrome)
- Brown, cystic area in left medulla from lack of circulation in one of the lateral arteries (branches of vertebral or posterior cerebellar, possibly)
What is this?
Medial pontine infarct
- Cystic area in midline area (right side of the picture)
- Affected basilar perforating arteries
What is the order of severity/”badness” of arteries in anterior circulation (ICA, ACA, MCA, branches)?
In order of severity:
Internal carotid > Ant/middle cerebral > branch occlusion of ACA/MCA
What is the most detailed way to image these arteries?
Cerebral arteriogram
- Femoral catheter run up to aortic arch to inject the carotids (although, can also inject vertebrals)
How can you differentiate internal and external carotids on arteriogram?
Internal is relatively straight/smooth running up to brain (may see sinus)
External has many branches (recall: head and neck)
What is another (non-arteriogram) method of imaging these arteries?
Carotid ultrasound
- Structural imaging
- Flow imaging (velocity; laminar vs. turbulent)
(Can see plaque on the wall inducing slow flow and turbulence)
Where does the anterior cerebral artery go? Branches? Supplies?
Anterior cerebral artery goes up/around corpus callosum (“pericallosal a”) and supplies superior, mesial lobes
Branches:
- Orbital
- Frontopolar a. (rostral end of cerebral hemisphere)
- Callosomarginal a. (big branch off pericallosal a.)
- Pericallosal a. (big terminal branch)
Big deficits due to loss of anterior cerebral artery?
Contralateral UMN disorder, especially of leg
Big deficits due to loss of middle cerebral artery?
Contralateral UMN disorder, especially of face and arm
What is the most common source of anterior strokes?
Middle cerebral artery
Branches of middle cerebral artery?
(Deep)
- Lenticulostriate arteries (supply striatum)
- Temporal branches
(Superficial)
- Precentral (pre-Rolandic a.)
- Central (Rolandic) a.
- Parietal branches
What is this? What is biggest artery?
Cerebral angiogram (contrast injected into artery from femoral threaded up to internal carotid)
- Largest here is internal carotid
(Structures seen depends on length of time after injection)
Risks of angiogram procedure?
- Hemorrhage at catheter site
- Dislodgment of atherosclerotic plaque (-> stroke)
What is this?
CT angiogram (CTA)
- Not quite as good of detail as angiogram, but good
- Arch M bit is the posterior cerebral arteries
- Can’t visualize posterior communicating
- Middle cerebral arteries coming off each side
