Anatomy of blood flow in CNS and consequences of disruption

Question 1

Define stroke

Answer 1

Cerebrovascular accident (CVA)
Rapidly developing focal disturbance of brain function of presumed vascular origin lasting more than 24 hours

Question 2

Define transient ischaemic attack

Answer 2

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

Question 3

What percentage of stroke is due to infarction and haemorrhage?

Answer 3

85% - infarction

15% - haemorrhage

Question 4

Define infarction

Answer 4

Degenerative changes that occur in tissue following occlusion of an artery

Question 5

Define cerebral ischaemia

Answer 5

Lack of sufficient blood supply to nervous tissue resulting in permanent damage if blood flow is not restored quickly due to hypoxia/anoxia

Question 6

What are the causes of occlusion?

Answer 6

Embolism - plugging of small vessel by material carried from larger vessel e.g. thrombi from the heart or atherosclerotic debris from the internal carotid

Thrombosis - formation of a blood clot (thrombus)

Question 7

Where does the posterior cerebral artery supply?

Answer 7

Supplies the lateral and medial parts of the posterior part of the hemisphere

Question 8

What does the anterior cerebral artery supply?

Answer 8

The medial part of the hemisphere

Question 9

What is associated with the disturbance of the anterior cerebral artery?

Answer 9

• Paralysis of contralateral leg > arm, face
• Disturbance of intellect, executive function and judgement (abulia)
• Loss of appropriate social behaviour

Question 10

What is associated with the disturbance of the middle cerebral artery?

Answer 10

• “Classic stroke”
• Contralateral hemiplegia: arm > leg
• Contralateral hemisensory deficits
• Hemianopia
• Aphasia (L sided lesion)

Question 11

What is associated with the disturbance of the posterior cerebral artery?

Answer 11

• Visual deficits
• homonymous hemianopia (loss of visual field on the same side in both eyes)
• Visual agnosia

Question 12

Define hemianopia

Answer 12

Blindness in over half the field of vision

Question 13

Define Aphasia

Answer 13

Loss in being able to speak

Question 14

What are lucunar infarcts?

Answer 14

Stroke that causes small holes to appear in the brain tissue. They appear in deep structures as a result of small vessel occlusion therefore symptoms can vary depending on the anatomical location of the vessel that has been occluded

Caused by hypertension

Question 15

What are the types of haemorrhagic stroke?

Answer 15

Extradural - Trauma, immediate effects. Arterial blood
Subdural - Trauma, delayed effects. Venous blood
Subarachnoid - usually caused by a ruptured aneurysm
Intracerebral - spontaneous hypertensive rupture of small vessels

Question 16

What are the differences in the dura between the skull and in the spine?

Answer 16

Skull two layers - periosteal and meningeal

Spine one layer

Question 17

What is the superior sagittal sinus formed by?

Answer 17

The peeling apart of the two layers of the dura in the skull

Question 18

What can found in the SSS?

Answer 18

Arachnoid granulations - subarachnoid space that protrude into the SSS.

Question 19

Why do extradural haemorrhages have a rapid onset?

Answer 19

Because it is usual due a rupture of a meningeal artery. Arteries carry blood at a high BP whereas veins are at a lower pressure so onset of symptoms is much slower

Question 20

What is the difference in vessels that rupture between a subdural and extradural haemorrhage?

Answer 20

Subdural - vein. Between dura mater and arachnoid layer

Extradural - artery. Between the dura mater and the skull

Question 21

What are the main risk factors for stroke?

Answer 21

• Age
• Hypertension
• Cardiac disease
• Smoking
• DM

Question 22

Draw and describe the arterial and venous blood supply to the brain.

Answer 22

Kenhub/Netters/slides

Question 23

Where does the middle cerebral artery supply?

Answer 23

The lateral parts of the hemisphere