Section 5 - Cerebrovascular Flashcards
List the most common sites of cerebral aneurysm.
- Jxn of ACA and anterior communicating a.
- ICA jxn with ACA or posterior communicating
- Bifurcation of MCA
- Bifurcation of basilar (either end)
- Along basilar a.
- Jxn of vertebral a. and PICA
What is a cerebral embolism?
Occlusion of cerebral vessel by extraneous material (clot, tumor cells, clump of bacteria, air, plaque fragments) leading to ischemia (localized anemia) and potentially infarction (necrosis)
What is a transient ischemic attack?
Sudden loss of neurological function resolved within minutes usually - small embolisms tend to occlude small cerebral vessels
Large embolisms tend to _____
occlude major vessels, causing sudden major neurological problems with permanent deficits or death
Atherosclerotic plaques at bifurcation of common carotid can _____
form emboli that occlude ICA
Septic emboli can interrupt blood flow or lead to infection, which can…
This can weaken the vessel wall and lead to a mycotic aneurysm
An air embolism can arise from _____
Dural venous sinus opened in surgical procedures
What is a penumbra?
Area immediately surrounding an ischemic or occlusive stroke which may be salvaged (“Time is brain”)
How do we treat penumbras?
- Tissue plasminogen activator within 3-4.5 hrs. (EXCEPT in hemorrhagic strokes)
- Endovascular clot removal within 8 hours
What is an arteriovenous malformation?
Lesions that consist of masses of tortuous larger arteries connected with large veins (no intervening capillary beds) with little/no brain tissue in mass
Why are arteriovenous malformations dangerous?
Dynamic lesions; lead to additional deficits. Can also lead to hemorrhage.
What is the treatment for arteriovenous malformations?
Surgical removal or endovascular embolization.
What are symptoms of an arteriovenous malformation?
- Hemorrhage (silent or defective)
- Seizures
- Mass effect (cranial nerve signs)
- Increased intracranial pressure
- Hydrocephalus
What is a hamartoma?
A benign, focal malformation. Tissue is the same as surrounding tissue, just malformed. Arteriovenous malformation is an example.
What is a malformation of the great cerebral vein of Galen?
(Special type of AVM) - Usually seen in newborns infants such that vein of Galen is GREATLY enlarged and fed by abnormal branches of cerebral and cerebellar aa.
What are symptoms of malformation of vein of Galen?
- Bulging fontanelles
- Progressive hydrocephalus
- Dilated veins on face/scalp
- HELLA big veinous blob on angiogram
Spinal AVMs:
- Usually larger in children
- Bleed less frequently; more localizing signs/symptoms
- Lower back pain, impaired micturition, sensory/motor
What are some consequences of ophthalmic artery occlusion?
- Significant visual loss ipsilateral
Ophthalmic-carotid intersection aneurysm can lead to visual loss from pressure on optic n.
What is Anterior Choroidal Artery Syndrome?
Occlusion of anterior choroidal artery
- Visual deficits
- Weakness of opposite upper and lower extremities (posterior limb of internal capsule)
(Hemiplegia, hemianesthesia, hemianopia)
What are some consequences of aneurysms on anterior communicating a. or anterior cerebral a.?
- Common visual deficits due to optic chiasm proximity (rupture collect blood in interhemispheric fissure)
- Distal ACA serves lower somatosensory/sensory cortex –> hemimotor and hemisensory deficits in lower extremity
What happens when M4 is occluded?
Serves trunk, upper extremity, face of somatomotor/sensory cortex, so associated deficits.
How do you treat carotid stenosis?
Endarterectomy within bifurcation.
Aneurysm of AICA may cause ______ symptoms (CN) since it crosses adjacent to them.
7 and 8
Aneurysms of anterior basilar bifurcation frequently affects _____
Oculomotor nerve (3)
What is vertebrobasilar insufficiency?
In hypertension, vertebral a. can be compressed between occipital bone and posterior arch of atlas (or extreme rotation can put torsion on artery) –> restrict blood flow
Occlusion of the P4 branch (mainly calcarine a.) lead to _____
Defect of primary visual cortex –> homonymous hemianopia of opposite visual fields (also seen in occlusion of more proximal PCA)
What is homonymous hemianopia?
Visual field loss on R or L side of vertical midline
What is a watershed infarct?
In cases of hypotension or embolic showers, border of perfusion between major aa. are particularly dangerous zone for hypoperfusion of distal vascular beds
ACA/MCA watershed infarct is “Anterior Watershed Infarct” and will result in:
- Contralateral hemiparesis of lower extremity
- Expressive language deficits, behavioral changes
MCA/PCA watershed infarct is “Posterior Watershed Infarct” and will result in:
- Partial visual loss
- Variety of language problems
Aneurysm of internal carotid a. in cavernous sinus will result in:
- Deficits in CN 3, 4, 6, V1, V2
- Partial/complete paralysis of eye movements
- Loss of corneal reflex
- Paresthesias or pain within V1 or V2
What causes a carotid-cavernous fistula?
Rarely results from ruptured aneurysm but may occur from secondary trauma
What is a cavernous sinus thrombosis?
Tumor or infection in orbit that can cause venous blood to flow toward cavernous sinus and potentially other parts of brain. Infection/tumor can spread from eye.
What is cerebral venous thrombosis? What is a symptom?
Blood clots within the venous structures of the CNS (resulting infarct is a venous infarct)
Increased intracranial pressure.
Where does cerebral venous thrombosis usually occur?
Sinuses, usually superior/inferior sagittal, straight, cavernous
What can cause cerebral venous thrombosis?
Severe dehydration, cachexia (weakness/wasting), hypercoagulable condition, birth control pills, sickle cell, diabetes mellitus, brain surgery, meningitis, traumatic injury
What are some complications of cerebral venous thrombosis?
Upstream to blockage becomes engorged and potentially edematous (maybe enough to hemorrhage)
Why must the artery of Adamkiewicz be protected in surgery?
Spinal medullary at T12, L1, L2 on left (large) that is major source of blood to lower thoracic and upper lumbar spinal cord
