This document discusses cerebral blood flow and stroke. It provides details on the anatomy and blood supply of the brain, different types of strokes including causes and locations. It describes the effects of infarctions in different arterial territories, focusing on deficits that can result from damage to areas supplied by the middle cerebral, anterior cerebral, and posterior cerebral arteries. Treatment options are also summarized, including both pharmacological interventions and surgeries.

1. Cerebral Blood
Flow & Stroke

2. Cerebral Circulation
Blood flow to CNS
delivers O2, glucose, nutrients
removes C O2, lactic acid, metabolites
Cerebral vasculature
unique anatomy & physiology
safety mechanisms
Brain highly vulnerable to disrupted
blood flow ~

3. Stroke
CVA: cerebrovascular accident
Failure of safety mechanisms
#3 cause of death for U.S. adults
#1 cause of chronic functional incapacity
about 2 million adults ~

4. CVAs
neurological symptoms and signs
usually focal
localized
acute
sudden onset
result from diseases involving
blood vessels. ~

5. Causes of CVAs
cardiac disease
trauma
infection
neoplasm (tumor)
exogenous toxins
arterio-venous malformations
(AVMs) ~

6. Types of CVAs
Occlusive CVA:
due to the closure of a blood vessel
-
usually due to atherosclerosis &
thrombosis.
Hemorrhagic CVA:
due to bleeding from a blood vessel
usually due to either hypertension or
an aneurysm. ~

7. Stroke: Ischemia
Insufficiency of blood supply
Glucose & O2 deprivation, build-up
of wastes
NOT synonymous Anoxia:
O2 deprivation only
Few seconds: little or no damage
6-8 minutes ---> Infarction
neurons & other cells die ~

8. Blood Supply of Brain
Arises from aortic arch
2 common carotid arteries
(extracranial)
give rise to external & internal carotid
2 vertebral arteries ~

9. aortic arch
external carotid
Posterior cerebral
basilar
vertebral
internal carotid
middle cerebral
anterior cerebral

10. Blood Supply: Arterial Territories
Internal carotid arteries
supply each cerebral hemisphere
branches:
anterior cerebral artery
middle cerebral artery
anterior choroidal artery ~

11. Anterior Cerebral Arteries
Surface branches
supply cortex and white matter of :
inferior frontal lobe
medial surface of the frontal and
parietal lobes
anterior corpus callosum ~

12. Anterior Cerebral Arteries
Penetrating branches supply:
deeper cerebrum
diencephalon
limbic structures
head of caudate
anterior limb of internal capsule ~

13. Middle Cerebral Arteries
Surface branches supply
cortex & white matter of
hemispheric convexity
(all four lobes and insula).
Penetrating branches
deep white matter
some diencephalic structures ~

14. Anterior Choroidal Arteries
Supply
anterior hippocampus &
posterior limb of the internal
capsule ~

15. Vertebral Arteries
Rise from subclavian artery
Branches
anterior spinal arteries &
posterior inferior cerebellar arteries.
2 vertebral arteries join at the junction of
the pons and medulla
form basilar artery
basilar divides into 2 posterior
cerebral arteries. ~

16. Posterior Cerebral Arteries
Surface branches supply
cortex and white matter of medial
occipital lobes
inferior temporal lobes
posterior corpus callosum
Penetrating branches supply:
parts of the thalamus
parts of the midbrain ~

17. Cerebral Artery Areas
1. anterior cerebral
2. Middle cerebral
3. Penetrating branches
of middle cerebral
4. anterior choroidal
5. Posterior cerebral
1
2
3
45
5

18. Anastomoses
Interconnections between blood vessels
overlapping blood supply
safety mechanism
retrograde filling
e.g., circle of Willis
Others between...
opthalmic artery & external carotid
surface branches of anterior, middle,
posterior ~

19. Functions of Cortical Areas

20. Frontal lobe
Prefrontal lobes
anterior to motor cortex
weigh consequences of future action
and plan accordingly (an executive
function);
performance of delayed responses
Inferior frontal lobes
emotional responding ~

21. Frontal lobe
Precentral gyri
control contalateral movement
Broca's area (L. Hemi.)
language production
R. Hemi.: may be more involved in
music production. ~

22. Parietal lobe
Postcentral gyrus
Anterior parietal lobe
primary somatosensory cortex (S1)
Posterior parietal cortex (PPC)
higher-order sensory areas
convergence from other sensory systems
left parietal lobe: reading and writing
right parietal lobe: spatial information. ~

23. Temporal lobe
Language & object recognition
memory
L. Hemi.: verbal information
R. Hemi.: nonverbal information
Inferior temporal lobes
higher-order visual perception ~

24. Temporal lobe
Superior temporal gyrus
primary auditory cortex (A1)
Superior temporal lobe
L. Hemi.: language comprehension
R. Hemi.: music comprehension
except trained musicians ~

25. Occipital Lobe
Analysis of visual information.
Primary visual cortex (V1)
Visual association cortex
color
movement
shape ~

26. Infarction in the territories of
the cerebral arteries

27. Middle cerebral artery
Most common stroke syndrome.
contralateral weakness
face, arm, and hand more than legs
contralateral sensory loss
face, arm, and hand more than legs
visual field cut
damage to optic radiations

28. Middle Cerebral Artery
Aphasia: language disturbances
more likely with L. Hemi. damage
especially men
Broca's: production
Wernicke's: comprehension ~

29. Middle Cerebral Artery
Impaired spatial perception
more likely after R. Hemi. damage
spatial neglect
dressing apraxia
constructional apraxia
topographagnosia ~

30. Anterior cerebral artery
Motor distrubance contralateral
distal leg
urinary incontinence
speech disturbance (may be more of
a motor problem)
apraxia of left arm (sympathetic
apraxia) if anterior corpus callosum
is affected
If bilateral may cause apathy, motor
inertia, and muteness ~

31. Posterior Cerebral Artery
Visual disturbances
contralateral homonymous hemianopsia
(central vision is often spared)
L. Hemi: lesions alexia
(with or without agraphia)
Bilateral lesions: cortical blindness
patients unaware they cannot see
(Anton's syndrome)
Memory impairment if temporal lobe is
affected ~

32. Posterior Cerebral Artery
Proximal occlusion
contralateral hemisensory loss,
spontaneous pain and dysesthesia if
thalamus affected
(thalamic pain syndrome)
contralateral severe proximal chorea
(hemiballism) ~

33. Treatment
Pharmacologic
anticoagulants
vasodilators
antihypertensives
steroids
antagonism of excitatory amino
acid neurotoxicity ~

34. Treatment
Surgery
remove aneurysms
remove pressure following
hemorrhage
Radiation to treat AVMs
Embolization therapy to
plug vessels of an AVM
or to treat an aneurysm
(direct surgery usually preferable)

35. Stroke Rescue?
Cell transplant - experimental
Inject immature nerve cells
grown from human cancer cells
Cells mature ---> bridge damaged areas
Rats: function restored
Human: June 23, 1998
no ill effects
no recovery yet ~