Vasculature To The Brain And SC

Question 1

What is the primary blood supply to the brain?

Answer 1

ICA’s (80%) and vertebral arteries (20%)

Question 2

What is the course of the ICA and vertebral arteries?

Answer 2

Pierce dura mater -> run in subarachnoid space and their branches penetrate into the brain parenchyma
Surrounded by perivascular (Virchow-Robin) space

Question 3

What are the components of the BBB?

Answer 3

Endothelial cell layer, basement membrane, pericyte, perivascular processes of astrocytes and oligodendrocytes

Question 4

Which arteries form the circle of Willis?

Answer 4

Anterior communicating, posterior communicating, anterior cerebral, posterior cerebral and ICA

Question 5

What is the clinical significance of the variation seen in the circle of Willis?

Answer 5

The ability of the unaffected portion of the circulation to hyper-perfuse the affected circulation is problematic -> may result in hypo-perfusion with associated ischemia or cerebral edema -> serious manifestations of diminished cerebral blood flow and may result in ischemic stroke or death

Question 6

Describe regional or focal ischemia

Answer 6

Seen in strokes where there is occlusion of a large nutrient artery
Results in ischemic penumbra (the tissue surrounded the ischemic territory which is too ischemic to function but critically viable)

Question 7

Describe treatments for regional/focal ischemia and the ischemic penumbra that results

Answer 7

Stroke therapy is directed at rescuing the penumbra by improving tissue acidosis and O2 delivery
Ca channel and NMDA receptor blocking drugs may prevent further neuronal damage
Autoregulation dysfunction and edema due to ischemic tissue acidosis and resultant luxury perfusion or adjacent normal tissue

Question 8

What occurs in global ischemia?

Answer 8

Distal areas of cerebral arterial circulation are hypoperfused and vulnerable to watershed infarction

Question 9

Which areas of the brain are consistently damaged in severe ischemic injury?

Answer 9

Certain areas of the brain (distal branches of the cerebral arteries) and particular neuronal populations (pyramidal cells of the hippocampus especially the CA1 or Sommer’s sector)

Question 10

Ischemia of the arterial supply of the SC most commonly occurs adjacent to what?

Answer 10

The enlargements at C2-3, T1-4 and L1

Question 11

What are watershed regions in the cerebrum?

Answer 11

Border zone regions supplied by major cerebral arteries where blood supply is decreased (due to infarctions)
The farthest regions supplied by arterial blood supply

Question 12

Ligation of which artery is being used for treatment of Parkinson’s?

Answer 12

AChA

Question 13

Infarction of the AChA is characterized by what?

Answer 13

Triad of hemiplegia, hemianesthesia and contralateral hemianopia
May also be associated with left neglect syndrome (right sided lesions) and speech disorders

Question 14

What does the PCoA supply?

Answer 14

Internal capsule and basal ganglia

Question 15

Which CNs is the ACA located near and what does it supply?

Answer 15

Located next to olfactory and optic nerves

Supplies anteromedial frontal cortex, anterior cingulate gyrus and paracentral lobe

Question 16

What is the clinical significance of the anterior cerebral A?

Answer 16

Occlusion of the ACA or superior sagittal sinus may result in sensory and/or motor deficits in the contralateral leg and foot
Highest incidence of cerebal aneurysm (35%)

Question 17

What does the middle cerebral A supply?

Answer 17

Internal capsule, corpus striatum, thalamus, primary auditory cortex, association cortex primary motor and primary somesthetic cortices, premotor and prefrontal cortices, Broca’s area, supramarginal and angular regions, Wernicke’s region

Question 18

What does a thrombosis in the central artery (of the MCA) cause?

Answer 18

Contralateral spastic paralysis and/or paresthesia of the face and upper 1/2 of body

Question 19

What causes Wernicke’s aphasia?

Answer 19

Caused by damage to the angular A (of the MCA)/obstruction of the MCA in the dominant hemisphere

Question 20

What is Wernicke’s aphasia?

Answer 20

A receptive language disorder in which pts are talkative/fluent but lack content or meaning in spoken and written language
Language pattern tends to have numerous inappropriate word choices and neologisms (new word creations)

Question 21

Occlusions in the MCA may result in what?

Answer 21

Sensory and/or motor deficits in the contralateral upper limb and head

Question 22

A thrombosis in the MCA results in what?

Answer 22

Expressive or Broca’s aphasia
A motor language disorder in which pts have a frustrating problem in initiating speech motor patterns
Certain automatic sometimes profane speech patterns may persist

Question 23

Which arteries are of the anterior circulation?

Answer 23

Branches of the ICA including AChA, PCoA, ACA and MCA

Question 24

Which arteries are of the posterior circulation?

Answer 24

Vertebral A, PICA and basilar A

Question 25

What does the anterior spinal A supply?

Answer 25

Central gray matter and anteromedial portion of white matter of the SC

Question 26

Which artery can be compromised during AAA repair or secondary to thoracolumbar fracture?

Answer 26

Greater anterior A of Adamkiewicz

Question 27

What does the posterior spinal A supply?

Answer 27

Dorsal roots, posterior 1/3 of spinal cord (most of the posterior column)

Question 28

An angiogram showing PICA displacement may indicate what?

Answer 28

A tumor

Question 29

What does the posterior inferior cerebellar A supply?

Answer 29

Posteroinferior portion of cerebellum, some medulla, choroid plexus of 4th ventricle

Question 30

Thrombosis of the posterior inferior cerebellar A may result in what?

Answer 30

Lateral medullary (Wallenberg) syndrome

Question 31

What does the posterior cerebral A supply?

Answer 31

Internal capsule, thalamus, choroid plexus of lateral ventricle and upper midbrain
Also supplies the inferior temporal cortex, visual association cortex and primary visual cortex

Question 32

All veins of the SC drain into what?

Answer 32

The internal venous plexus of Bateson (located in the epidural surface)

Question 33

Describe the superficial venous drainage of cerebral hemispheres

Answer 33

Drains most of the cortex of the lateral cerebral hemispheres
Empties into the cavernous sinus, superior sagittal sinus, transverse sinus via the superior and inferior anastomotic veins

Question 34

Thrombosis of the superior sagittal or right transverse sinus results in what?

Answer 34

Cortical ischemia and/or necrosis

Question 35

Thrombosis of the straight sinus or left transverse sinus results in what?

Answer 35

Ischemia/necrosis of deep cerebrum

Usually fatal