Cerebrovascular Disease Flashcards
Understand different functions of the brain
know the different cortexes
Go over the primary motor and sensory cortex
review image
Blood supply to the brain:
review carotid
internal cartoid
ect
Know circle of Willis
Know branches of circle of Willis
Functional areas of the brain
Blood supply by major divisions
Location of MCA
Location of Lacunar vessels
Location of watershed infarcts
ACA-MCA
MCA-PCA
Path of the midbrain
Posterior limb is location of corticospinal tracts; may see lacunar infarct here
Where is the pyramidal decussation?
In the brain stem
Review of corticospinal tract
note how lateral coticospinal crosses in the decussation (motor for distal muscle)
anterior doesn’t until level of spinal cord (proximal muscles and trunk muscles)
Damage here see contralateral paralysis: upper limb and face
Contralateral loss of sensation to upper limb and face
Aphasia if in dominant hemisphere
Hemineglect if lesion affects non-dominant (often right) side
MCA
(feeds motor and sensory cortex, Temporal lobe at Wernikes area and frontal lobe at Broca’s area)
Contralateral paralysis of Lower limb and Contralatera loss of sensation of lower limb
ACA supplies both motor and sensory cortex for lower limb
Contralateral hemiparesis/hemiplegia
Lenticulostriate artery: common location of lacunar infacts 2nd to unmanaged HTN!
lesion would be in the striatum, internal capsule
Contralateral hemiparesis–upper and lower limbs and decreased contralateral proprioception. Ispilateral hypoglossal dysfnx (tongue deviates ipsilaterally)
ASA supplies: lateral coticospinal tract and medial lemnisucs as well as caudal medulla (hypoglossal nerve)
***MEDIAL MEDULLAY SYNDROME (often bilateral stroke)
Vomit/nystagmus/vertigo with decreased pain and temp sensation from ipsilatareal face and contralateral body
Dysphagia, hoarsness and decreased gag with ipsilateral horner syndrome, ataxia and symetria
PICA
***Lateral medullary syndrome or Wallenburg syndrome
(Dont Pick A horse that can’t eat) PICA, horsness, dysphagia
Vomit/vertigo/nystagmus
paralysis of face, decreased lacrimiation, salivation, decreased taste from anterior 2/3 of tongue, decreased corneal reflex
FAce: decreased pain and temp
Ipsi decreased hearing and ipsi horner syndrome
ataxia and dymetria
AICA; facial nucleas effects specific to AICA lesions
**Lateral pontine syndrome
“FAcial droop means AICA’s pooped”
Contralateral hemianopia with macular sparing
PCA
supplies occipital cortex and visual cortex
Preserved consiousness adn blinking
quadriplegia, loss of voluntary facial, mouth and tounge movements
“Locked-in syndrome”
Basilar Artery stroke
supplies: pons/medulla, lower midbrain, corticospinal and bulbar tract, ocular cranial nerve nuclie, paramedian pontine reticular formation
CNIII palsy
eye is down and out with ptosis and pupil dilation
Pcom
*common site of saccular aneurysm, lesions are usually aneurysms, not strokes
Affect of Acom anuerysm
visual field defects: can lead to stroke: saccular or berry aneurysm can impinge cranal nerves
Hypoxia (deprivation of O2) - in brain occurs by several mechanisms: list 3
Low level of oxygen in blood (ex. respiratory arrest, near drowning, severe anemia, carbon monoxide poisoning)
Low blood flow to tissue-ischemia (ex. cardiac arrest, vessel obstruction, increased intracranial pressure)
Oxygen utilization by tissue is impaired (ex.-cyanide poisoning)
= low blood flow
causes more damage than hypoxia
Ischemia
Describe Global Ischemia
systolic pressure < 50 mmHg
Generalized reduction in cerebral perfusion, usually due tocardiac arrest, shock, or severe hypotension; outcome dependent upon severity & duration of ischemia
Where is damage the worst in Global ischemia?
Brain damage is most severe in watershed/borderzone territories
If severe, widespread neuronal death may result in :
Persistent vegetative state
Brain death
Case for Global Ischemia
infarction from obstruction of local blood supply (stroke)
Results most often from arterial stenosis and/or thrombosis, atheroemboli, or thromboemboli.
Focal Ischemia
What are the borderzone areas that are vulnerable in global cerebral ischemia?
Low flow areas between anterior, middle and posterior cerebral arteries
Certain brain cells and regions are more susceptible to hypoxia/ischemia than others
Most vulnerable cells (in decreasing order)
– neurons, oligodendrocytes, astrocytes
Most vulnerable regions to hypoxia and ischemia– adults (in decreasing order)
Hippocampus (CA1 sector – Sommer sector)
Lamina 3 and 5 of cerebral cortex (laminar necrosis)
Purkinje cells in cerebellum
What determines the selective vulnerability?
Variable oxygen/energy requirements of different neurons and neuronal populations
Glutamate receptor densities: Glutamate is neurotoxic when present in excess, as occurs in hypoxic/ischemic brain damage
Describe what you see on histology in acute hypoxia/ischemia
“Red is dead”
Pyknotic cell with shrunken & dark nucleus, no nucleolus visible
Red cytoplasm (no Nissl substance visible)
What area of brain is infarcted and why
Hippocampal infarct: selective vulnerability