3: Blood supply of the brain

Question 1

For which percent of the body weight and cardiac output does the brain makes up?

Answer 1

Only 2% of body weight but

10- 20% of cardiac output

Question 2

Which two major arteries supply the brain with blood?

Answer 2

• Internal carotid artery
• Vertebral arteries

Question 3

What is the circle of Willis?

Answer 3

Anastomosis of arteries supplying the brain

–> allows collater circulation in the cerebral circulation

Question 4

Answer 4

Question 5

Answer 5

Question 6

Answer 6

Question 7

Answer 7

Question 8

Answer 8

Question 9

Answer 9

Question 10

Answer 10

Question 11

Summarise the overall venous drainage of the brain

Answer 11

—Cerebral veins

—–> Venous sinuses (in subarachidonic space) –>

— –> Dura mater

—Internal jugular vein

Question 12

What is a —Cerebrovascular accident (CVA)?

Answer 12

A Stroke

rapidly developing focal disturbance of brain function of presumed vascular origin and of >24 hours duration

–> 85% infarction, 15% hemmorage

Question 13

What is a Transient Ischaemic Attack (TIA)?

Answer 13

rapidly developing focal disturbance of brain function of presumed vascular origin that resolves completely within 24 hours

–> warning sign: patients are at hight risk of getting a stroke!

Question 14

What is an infarction?

Answer 14

—Degenerative changes which occur in tissue following occlusion of an artery

Question 15

What is cerebral ischemia?

Answer 15

—Lack of sufficient blood supply to nervous tissue resulting in permanent damage if blood flow is not restored quickly

—

— hypoxia/anoxia

Question 16

What are posiible causes for an occlusion

Answer 16

• Thrombus (blood cloth at site of formation)
• Embolus (any other substance or other blood cloth formed in another place)

Question 17

What are the main risk factors for stroke?

Answer 17

• Age
• Hypertension
• Cardiac disease
• Smoking
• Diabetes mellitus

Question 18

Which part of the brain is supplied by the anterior cerebral artery?

Answer 18

Medial two thirds of the Cortex

• Medial prtions of frontal lobes
• Superior medial parietal lobes

Question 19

Which part of the brain is supplied by the middle cerebral artery?

Answer 19

Lateral 2/3 of cortex + forebrain

Question 20

Which part of the brain is supplied by the posterior cerebral artery?

Answer 20

The occipital lobe (posterior part)

Question 21

Which symptoms might occur when ther is a blockage to the anterior cerebral artery?

Answer 21

Paralysis of

• contralateral leg (more than arm)
• face

Disturbance of intelect, executive function and judgement (–>abulia)

Loss of appropirate social behaviour

Question 22

Which symptoms might occur when there is a occlusion of the middle cerebral artery?

Answer 22

“Classic stroke”—

• Contralateral hemiplegia (=hemiparesis): arm rather than leg
• —Contralateral hemisensory (=altered sensation) deficits
• —Hemianopia (optical disturbance (blurred/blindness)
• —Aphasia (L sided lesion) (loss of speach)

Question 23

What is hemiplegia?

Answer 23

Hemiparesis

(half sided paralysis)

Question 24

What is hemianopia?

Answer 24

Visual field loss in a vertical line

Question 25

What is Aphasia

Answer 25

Loss of speach (can also be eiter efferent (understanding) or afferent (speaking))

Question 26

What is Broca's aphasia?

Answer 26

It is expressice loss of speach due to damage to the **broca region**

Question 27

What is Wernicke's aphasia?

Answer 27

Receptive aphasia * loss of understnading of speech --\> due to damage to the Wernicke region of the brain

Question 28

How does a paitent with blockafe of the posterior cerebral artery might present?

Answer 28

—Visual deficits * **homonymous hemianopia** (hemianopic visual field loss on the same side of both eyes) * visual agnosia (impaired visual perception)

Question 29

What is a Lacunar Infarct?

Answer 29

* —Lacune is a small cavity formed by tissue loss due to former strokes * —Appear in deep structures as a result of small vessel occlusion * —Deficit is dependent on anatomical location * Main risk factor: —Hypertension

Question 30

What are the characteristice of a subarachnoid hemorrhage?

Answer 30

Usually ruptured aneurysm * Rupture can be due to trauma * or spontaneous

Question 31

What are the characteristics of a intercerebral hemorrhage?

Answer 31

Usually spontaneous * closely linked to hypertension

Question 32

Explain the organisation of the dura mater in relation to the cerebral sinuses?

Answer 32

Dura surrounds the sinuses

Question 33

Compare a subdural vs. an extradural (epidural) haematoma

Answer 33

Subdural: * venous * slow * can be traumatic or spontaneous (more common in eldrely) Extradural * arterial * quicker * usually traumatic (more common in young patients)

Question 34

Which symptoms would you expect with and occlusion of the anterior cerebral artery?

Answer 34

Supplies part of motor cortex to legs: * paralysis/weakness in contralateral leg * loss of sensation in contralateral leg * Abulia --\> no motivation * inability to initiate the process of walking (gait appraxia) * urinary incontinence

Question 35

Where would you suspect someone to have a leasion if one presents with following symptoms: * paralysis/weakness in contralateral leg * loss of sensation in contralateral leg * Abulia --\> no motivation * inability to initiate the process of walking (gait appraxia) * urinary incontinence

Answer 35

In the anterior cerebral artery

Question 36

Which symptoms would a patient present with when having an occklusion in the basilar artery?

Answer 36

Present with locked-in syndrome

Question 37

Which part of the brain dos the middle cerebral artery supply?

Answer 37

* A lot of the lateral surface of the hemisphere * (location of Broca's area i.e. language expression) * Inferior division supplies lateral temporal lobe (location of Wernicke's area i.e. language comprehension) * Deep branches supply the basal ganglia as well as the internal capsule

Question 38

Which symptoms might someone present when there is an occlusion of the middle cerebral artery?

Answer 38

* Paralysis + sensory loss of contralateral face and arm * Aphasia (dependant of side of brain if Broca of Wernicke) --\> usually left * contralateral neglect syndrome * Contralateral homonymous hemianopsia is often present

Question 39

When someone presents with following symptoms: Where would you supect a leasion to be? * Paralysis + sensory loss of contralateral face and arm * Aphasia (dependant of side of brain if Broca of Wernicke) --\> usually left * contralateral neglect syndrome * Contralateral homonymous hemianopsia is often present

Answer 39

Middle cerebral artery

Question 40

When someone is haveing an occulusion in the posterior cerebral artery, what do you expect the symptoms to be?

Answer 40

Supplies the: Occipital lobe, Basal ganglia in temporal lobe, Thalamus, lateral+3rd ventricle * Contralateral loss of pain and temperature sensations. * Visual field defects (contralateral hemianopia with macular sparing). * Prosopagnosia --\> no recognition of faces * Ipsilateral deficits of oculomotor nerve, * Contralateral deficits of facial nerve (only lower face, upper face receives bilateral input), vagus nerve and hypoglossal nerve

Question 41

Someone presenting with following symptoms: Where do you expect the leasion to be? * Contralateral loss of pain and temperature sensations. * Visual field defects (contralateral hemianopia with macular sparing). * Prosopagnosia --\> no recognition of faces * Ipsilateral deficits of oculomotor nerve, * Contralateral deficits of facial nerve (only lower face, upper face receives bilateral input), vagus nerve and hypoglossal nerve

Answer 41

Posterior cerebral artery

Question 42

What is a Berry aneurism? What does it cause?

Answer 42

It is a saccular aneurism in the brain * most common cause for sub-arachnoid haemorrhage