3. Anatomy of the blood supply
of the brain
Abdullah Ismail Alwehaibi
433025171
4. • Normal blood supply of the
brain is achieved by 2 systems
1. Anterior system ( carotid
system)
2. Posterior system
(Vertebrobasilar system)
5.
6. Anterior system ( carotid system)
• Right Common Carotid Artery:
– Begins at the bifurcation of the
brachiocephalic (Innominate) artery
behind the right sternocostal joint.
– Has only a cervical portion.
7. • Left Common Carotid Artery:
– Springs from the highest part of the arch of the
aorta to the left.
– Has a thoracic and cervical portion.
– The CCA bifurcates into the internal and external
divisions at the level of the second or third
cervical vertebrae
8. Identify A ,B and C
A
C
B
A-Common Carotid Artery
B- External Carotid Artery
C-Internal Carotid Artery
9. Internal Carotid Artery:
• Begins at the level of the upper border of the
thyroid cartilage.
• The ICA has a tortuous course through the
carotid canal & inside the cranium (with 6 bends)
• The bended intracranial part is known as the
carotid siphon which is clearly seen in
radiographs
• Consist of four portions.
– Cervical
– Petrous
– Cavernous
– Cerebral
11. • Internal Carotid Artery branches:
– Hypophysial arteries: further splits into
• anterior hypophysial artery:
– hypothalamus
• –posterior hypophysial artery:
– neural lobe of the pituitary
– Ophthalmic artery:
• eyes, paranasal sinuses and parts of the nose
– Posterior communicating artery:
• runs backward to join the posterior cerebral artery
– Anterior choroidal artery:
• choroid plexus of temporal horn of lateral ventricles and optic tract,
hippocampus
• Terminal Branches
– Middle Cerebral Artery
– Anterior Cerebral Artery
12. Posterior system (Vertebrobasilar system)
• The right and left vertebral
arteries arise from
the subclavian
• Pass through foramen
transverse C6- C1
• Enters through foramen
magnum
• the two vertebral arteries join
to form the basilar artery at
the lower Pons border
13. • Branches off the vertebral artery
1. spinal artery:
• anterior spinal artery:
• posterior spinal artery:
2. posterior inferior cerebellar artery (PICA):
• largest branch off vertebral artery, supplies
cerebellar hemisphere, inferior vermis, etc.
14. • Basilar Artery:
– Formed by the junction of the two vertebral
arteries.
– Extends from lower to upper border of the pons,
lying in its median groove.
15. • Branches of basilar artery
1. anterior inferior cerebellar
artery (AICA)
• supplies inferior surface of the
cerebellum
2. labyrinthine artery
• supplies the membranous
labyrinth of the internal ear
3. Pontine arteries
• supply pons and pontine
tegmentum
4. superior cerebellar artery
• supplies pons, superior cerebellar
peduncle.
• Basilar artery Ends by dividing into
the two Posterior Cerebral arteries.
16. Circle of Willis
• Circle of Willis
– Consists of :
• anterior cerebral
• anterior communicating
• internal carotid
• posterior communicating
• posterior cerebral arteries.
17. CEREBRAL blood supply
• Normal blood supply of the brain is achieved
by:
– Anterior cerebral artery.
– Middle cerebral artery.
– Posterior cerebral artery.
18. Anterior Cerebral Artery
• The anterior cerebral artery
extends upward and forward
from the internal carotid
artery.
• It supply most of the medial
and superior surfaces of the
brain and the frontal pole.
• The parts of the brain that
control logical thought,
personality, and voluntary
movement
19. Middle Cerebral Artery
• The middle cerebral artery is
the largest branch of the
internal carotid.
• Origin:
– Continuation of internal
carotid artery
• The artery supplies a portion
of the frontal lobe and the
lateral surface of the
temporal and parietal lobes
• Left middle cerebral artery
supplies language center.
20. Posterior cerebral artery
• Origin:
– Terminal branch of
basilar artery
• The artery supplies
the occipital and
temporal lobe
auditory
21.
22.
23. • Which of the following is not a part of circle of
Willis:-
A. Anterior cerebral artery
B. Posterior cerebral artery
C. Middle cerebral artery
D. Posterior communicating artery
E. None of the above
26. • The brain requires 20 % of the total blood
pumped by the heart.
• The brain Requires constant supply of oxygen
and glucose
• glucose and oxygen can’t be stored!!
27. • Stroke :
– Defined as an acute neurological deficit lasting
more than 24 hours caused by cerebrovascular
aetiology.
– Stroke is a leading cause of morbidity and
mortality.
28. • Type of stroke :
– ischaemic stroke
• (caused by vascular occlusion or stenosis
• 85% of strokes
– haemorrhagic stroke
• caused by vascular rupture, resulting in
intraparenchymal and/or subarachnoid
haemorrhage.
– Transient ischaemic attack (TIA)
• defined as a transient episode of
neurological dysfunction caused by focal
brain, spinal cord, or retinal ischaemia,
without acute infarction
33. Etiology
• Result from events that limit or stop blood
flow:
• Thrombotic embolism
• Thrombosis in situ
• Large Artery Stenosis
• Relative hypoperfusion
34.
35. RISK FACTORS
• Age: 40+
• Race: more in blacks
• Gender: less in female pre-menopause more
post-menopause
• Family history of strokes
• Previous history of strokes
36. Signs And Symptoms
• Hemiparesis, monoparesis
• Hemisensory deficits
• Monocular or binocular visual loss
• Visual field deficits
• Dysarthria
37. Sign And Symptoms
• Aphasia
• Sudden decrease in the level of consciousness
• Facial droop
• Ataxia
41. Investigations
• Non-contrast CT head (STAT):
• To rule out hemorrhage and assess extent of
infarct
• MRI
• ECG
• Lab:
• CBC, electrolytes, creatinine, PTT/INR, blood
glucose
• Carotid Doppler
• MRA
42.
43. Medical management of stroke
• Initial Treatment
• The goal for the acute management of
patients with stroke is to stabilize the patient
and to complete initial evaluation and
assessment, including imaging and laboratory
studies, within 60 minutes of patient arrival.
44. Table 1. NINDS* and ACLS** Recommended Stroke
Evaluation Time Benchmarks for Potential
Thrombolysis Candidate
Time Interval Time Target
Door to doctor 10 min
Access to neurologic expertise 15 min
Door to CT scan completion 25 min
Door to CT scan interpretation 45 min
Door to treatment 60 min
Admission to stroke unit or ICU 3 h
*National Institute of Neurological Disorders and Stroke
**Advanced Cardiac Life Support guidelines
45. Ischemic stroke
• To treat an ischemic stroke, doctors must quickly
restore blood flow to your brain.
•
Emergency treatment with medications. Therapy
with clot-busting drugs must start within 4.5
hours if they are given into the vein. Quick
treatment not only improves your chances of
survival but also may reduce complications .
50. Carotid Endarterectomy
• A carotid endarterectomy is a surgical procedure to
open or clean the carotid artery from the stenotic
plaque with the goal of stroke prevention.
Indications:
• Symptomatic patients with 50-99% stenosis .
• Asymptomatic patients with greater than 60%
stenosis .
51. Asymptomatic with >60 %
stenosis:
Ipsilateral 5-year stroke
rate was:
Patients undergoing CEA
5.1%
Patient receiving best
medical therapy 11%
Symptomatic with >70%
stenosis:
Ipsilateral 2 year stroke rate
was:
Patients undergoing CEA:
9%
Patient receiving best
medical therapy: 26%
52. • Rarely, endarterectomy is performed on patients with completely
occluded carotid arteries. Candidates for surgery include those who
have:
1. Recent endarterectomy with immediate postoperative thrombosis.
2. Bruit disappears under observation while remaining asymptomatic.
3. Recent occlusion with fluctuating or progressive symptoms.
4. New internal carotid occlusion that can be operated on within 2 to
4 hours of the onset of symptoms.
53. Contraindications
• Patients with a severe neurologic deficit after a
cerebral infarction
• Patients with an occluded carotid artery
• Concurrent medical illness that would significantly
limit the patient’s life expectancy
54. Techniques
• Anesthesia for CEA can be general endotracheal
anesthesia, regional cervical block, or local
anesthesia.
• The choice of anesthesia depends on a combination
of patient factors and surgeon expertise.
• No single method of anesthesia has been
demonstrated superior.
60. Postoperative care
• Immediately after endarterectomy, neurologic function
and blood pressure (BP) alterations should be
monitored.
• Hypertension and hypotension are common after
endarterectomy and may cause neurologic complications.
• The extremes of BP should be treated with either sodium
nitroprusside or phenylephrine (Neo-Synephrine) to keep
the systolic BP between 140 and 160 mm Hg (slightly
higher in chronically hypertensive patients)
61. Postoperative care
• The wound should be examined for hematoma formation.
• Aspirin is resumed in the immediate postoperative period.
• Some advocate the use of dextran-40 (up to 20 mL/kg/day
for up to 72 hours) as an additional antithrombotic agent,
which can be started intraoperatively and continued into
the early postoperative period.
62. Patient follow-up
• A baseline duplex scan is obtained 3 months after
the procedure and again at 12 months. Patients can
then be followed yearly.
• Patients who can tolerate aspirin are given 325
mg/day.
63. Complications
• Myocardial infarction (MI) remains the most common
cause of death in the early postoperative period.
As many as 25% of patients who undergo endarterectomy
have severe, correctable coronary artery lesions.
• Cranial nerve injuries occur in 5% to 10% of patients who
undergo CEA.
The most commonly injured nerve is the marginal mandibular,
followed by the recurrent laryngeal, superior laryngeal, and
hypoglossal nerves.
• Recurrent carotid stenosis has been reported to occur in
5% to 10% of cases, although symptoms are present in
fewer than 3%.
64. Carotid Angioplasty and Stenting
• The indications for CAS are the same as those for a
CEA
Have higher risk of stroke!!!
65. • Because CEA is well tolerated and has a very low
risk of complications, CAS is commonly reserved
for high-risk patients, including patients with the
following conditions:
a. Severe cardiac disease.
b. Severe chronic obstructive pulmonary disease
(COPD).
c. Severe renal insufficiency or end-stage renal
disease (ESRD) requiring hemodialysis.
d. Prior ipsilateral neck surgery.
e. Prior neck radiation.
f. Contralateral vocal cord paralysis.
g. Surgically inaccessible lesion
66. contraindications to CAS include the
following:
• a. Severe tortuosity of common and ICA.
b. Complex aortic arch anatomy (increasing
difficulty as great vessels arise from ascending
rather than transverse aortic arch).
c. Severe calcification or extensive thrombus
formation.
d. Near-complete or complete occlusion.
67.
68.
69. How can we stop Embolization??
• Embolization of plaque debris has been shown to occur with almost
any endovascular manipulation of a carotid artery lesion.
• Consequently, embolic protection devices have been developed
that significantly reduce the risk of stroke during CAS.
• The typical device used today is a filter-like device that is advanced
across the lesion and then opened in the distal ICA prior to
angioplasty and stent deployment.
70.
71.
72. complications
• Embolic stroke is the most common complication of
CAS
Risk factors
• include lack of a cerebral protection device
• long or multiple lesions
• age older than 80 years
• Thrombolysis may be a successful treatment option,
especially if the source of emboli is an acute
thrombus.
73. complications
• Hemodynamic instability may occur during
manipulation and angioplasty of the carotid
bifurcation.
• Bradycardia should be anticipated and treated
with atropine prior to dilation of the carotid
bifurcation.
• Postoperatively, as with CEA, patients should
be monitored to avoid extremes of BP.
74. complications
• Restenosis occurs in approximately
5% of patients at 12 to 24 months
and is typically secondary to intimal
hyperplasia
75. Follow-up
• using duplex ultrasound is important to identify
patients with restenosis and is usually performed
at baseline following CAS and then at 3, 6, and 12
months and every year thereafter.