202 - Stroke

Question 0

What are the two types of stoke and how common is each?

Answer 0

Ischaemic (85%) - embolic (lodging of a blood clot fat or gas in blood stream) and ‘in situ thrombotic (forming of a blood clot in place)

Haemorrhagic (15%) - burst blood vessel

Question 1

Define a stroke

Answer 1

A neurological deficit related to a non traumatic vascular event

Question 2

Define a Transient Ischaemic Attack

Answer 2

A neurovascular event with symptoms lasting less than 24 hours

Question 3

what are the cardinal features of strokes?

Answer 3

• Focal - particular location
• Negative clinical phenomena - no added signs like twitching
• Relate to arterial anatomy (i.e. not veins)
• Sudden onset
• Px has identifiable vascular risk factors - poor diet, smoking, no exercise

Question 4

What are the risk factors for embolic strokes?

Answer 4

• Atheromatous disease - smoking, family Hx, diabetes, hypertension
• Cardiac causes - AF, endocarditis, shunts, cardiomyopathy
• Low cardiac output states

Question 5

What are the risk factors for ‘In Situ’ thrombotic strokes?

Answer 5

• Atheromatous Disease
• Hyperviscosity -excess RBCs
• Vasculitis
• Thrombophilic states - F5 leiden (blood clotting disorder), pregnancy, oral contraceptive pill
• Incr. alcohol intake

Question 6

What are the risk factors for Haemorrhagic strokes?

Answer 6

• Hypertension
• on anti coagulation drugs
• on thrombolysis drugs

Question 7

What are the risk factors for venous strokes?

Answer 7

• Dehydration
• Infection
• Heart Failure
• Thrombophilic states - CA, pregnancy, OCP

Question 8

Describe a Primary Intracranial haemorrhage (PICH)

Answer 8

• Hyper acute and sometimes LOC & headache due to incr. in Intracranial pressure (cushing’s reflex)
• A ruptured vessel in R hemisphere would cause L hemiparesis

Question 9

Describe a Sub Arachnoid Haemorrhage (SAH)

Answer 9

• Hyper acute & meningism (neck stiffness) & LOC
• Extra-cerebral anuerysm
• Thunderclap headache

Question 10

Describe Cerebral Venous Sinus Thrombosis (CVST)

Answer 10

• DVT of the brain
• Sub acute / evolving - back pressure in the veins
• Secondary bleeding, incr. in ICP
• Don’t respect arterial territories
• Affects young people, women on OCP

Question 11

Describe Brainstem and spinal strokes

Answer 11

• Ataxia, diplopia (double vision), dysarthria, lower CNS hemiparesis
• Ipsilateral on face and contralateral on arms and legs

Question 12

What does optic disc selling indicate?

Answer 12

Incr. BP caused over a long time - therefore not a stroke

Question 13

Describe the autoregulation of cerebral blood flow.

Answer 13

CBF is maintained at the same rate over a range of blood pressures (50-170 mmHg) by variation in arteriolar control

Question 14

How does chronic hypertension affect affect autoregulation of CBF?

Answer 14

The range is reset to a higher level. If BP too low arteriolar system no longer compensates and Px blacks out (CBF inadequate for metabollic demands, impaired cellular metabolism & decr. neuronal activity). If BP too high leads to cerebral oedema, hypertensive encephalopathy and hyperaemia.

Question 15

What can cause the failure of autoregulation?

Answer 15

• Incr. age
• Head Trauma
• SAH or Ischaemic stroke
• Cerebral Hypoxia
• High pCO2

Question 16

At what percentage fall from the normal range of CBF will tissue be at a risk of ischaemic damage?

Answer 16

50%

Question 17

Describe what glial cells are and how they metabolise

Answer 17

They are non-neuronal support cells that maintain homeostasis, form myelin and supply lactate to adjacent neurons. They metabolise aerobically and anaerobically.

Question 18

Describe what neurons metabolise and how they metabolise

Answer 18

They can metabolise glucose but mostly metabolise lactate from the glia. They are obligate aerobes and are very sensitive to ischaemia, suffering irreversible damage after 5-7 mins of hypoxia.

Question 19

What is the difference between ischaemia and hypoxia?

Answer 19

Ischaemia is a restriction in blood supply that leads to dysfunction +/- damage.
Hypoxia is oxygen deprivation due to low 02 in inspired air, airway obstruction, lung disease, reduced O2 carrying capacity of blood, ischaemia & inhibition of aerobic respiration

Question 20

What are the effects of ischaemia/hypoxia dependent on?

Answer 20

The degree and duration of ischaemia/hypoxia, temp (low temp prevents damage) and blood glucose (incr. glucose causes incr. damage due to build up of lactic acid that cannot be metabolised.

Question 21

What is global ischaemia?

Answer 21

Interruption of circulation and general reduction in cerebral profusion due to:

• Cardiac arrest
• Severe hypotension
• Shock

Question 22

What does global ischaemic lead to?

Answer 22

• Selective neuronal necrosis
• Cortical Laminar Necrosis
• Watershed infarcts - at areas between different arterial supplies due to poor blood supply from distal end arteries

Question 23

What does global ischaemia cause clinically?

Answer 23

• Transient confusion
• Focal deficits
• Non perfused brain and brain death (ICP>arterial BP)

Question 24

How is the risk of a stroke affected if a Px has a TIA?

Answer 24

7-10% risk

Question 25

Where do intracerebral haemorrhages most commonly found?

Answer 25

Thalamus/basal ganglia

Question 26

What most commonly causes sub arachnoid haemorrhages?

Answer 26

Rupture of saccular Aneurysms. Aneurysm most commonly occur in anterior circle of willis

Question 27

What is a Lacunar Infarction?

Answer 27

Ischaemic stroke cause by occlusion of lenticulostriate arteries (arise off MCS). Associated with chronic hypertension and affect the basal ganglia, thalamus, internal capsule and pons leading to formation of a small lacuna (holes)

Question 28

what causes a stroke secondary to cerebral vasculitis and how is it treated?

Answer 28

inflammation of blood vessel walls in brain often due to rheumatoid arthritis, SLE or drug abuse. Treated by immunosupression (glucocorticoids)

Question 29

What is Binswager's disease?

Answer 29

Multi-infarct dementia caused by a combiation of artherosclerosis, embolism, chronic HTN

Question 30

What imaging technique works best for venous strokes?

Answer 30

CT venography

Question 31

How are venous strokes treated?

Answer 31

Anticoagulation even if small haemorrhages present as you must remove the thrombus to remove the back pressure first. Thrombolysis if anticoagulation not working.