stroke - + ila

Question 1

What is the definition of a stroke?

Answer 1

Definition = an acute neurological deficit lasting more than 24 hours and caused by cerebrovascular aetiology. It is subdivided into:

• Ischaemic stroke = caused by vascular occlusion or stenosis
• Haemorrhagic stroke = caused by vascular rupture, resulting in intra-parenchymal, subarachnoid, and/or intraventricular haemorrhage.

Question 2

define cardioembolic stroke

Answer 2

• when heart isn’t functioning properly - it results in a lack of blood flow to the brain eg arrhythmias, HF, embolisms
• most common way this happens is formation of blood clots in the LA which travel to brain

Question 3

define haemodynamic stroke

Answer 3

sudden drop in blood pressure which reduces the perfusion to the brain, leading to ischaemia and potential stroke

Question 4

explain what happens to the effected area in a stroke

Answer 4

• area directly affected by the artery undergoes irreversable damage
• the surrounding area - the penumbra - has lower oxygen levels but still viable neurons that can be salvaged with timely reperfusion

Question 5

causes of haemorrhagic stroke

Answer 5

high blood pressure
aneurysms
arteriovenous malformations

Question 6

where do vertebral arteries enter the skull

Answer 6

foramen magnum

Question 7

describe the terratories of the anterior, middle and posterior cerebral arteries

Answer 7

● Anterior cerebral arteries = supplies anteromedial portion of cerebrum.

● Middle cerebral arteries = supplies majority of lateral part of brain.

● Posterior cerebral arteries = supply both the medial and lateral parts of posterior
cerebrum.

Question 8

explain the symptoms and functions affected with occlusion of each artery

Answer 8

anterior cerebral artery:
- behavioural changes
- more common to see weakness in legs than arms
- mild sensory defect

middle cerebral artery:
- weakness
- face > arms > legs
- aphasia
- hemisensory defect
- homonymous hemianopia

posterior cerebral artery:
- homonymous hemianopia
- visual agnosia
- prosopagnosia

Question 9

What term is used to describe the transient visual disturbance this patient experienced and why does it occur?

Answer 9

amaurosis fugax
- can be in one or both eyes
- considered a TIA
- lasts from seconds to minutes followed by full recovery
- hypoperfusion of retina or optic nerve

Question 10

explain the pathophysiological process of raised ICP

Answer 10

CUSHINGS TRIAD
- ischaemic/necrosing tissue creates an inflammatory response
- blood also creates an inflammatory response in the case of haemorrhagic stroke
- CSF and arteries become squashed - pressure isnt high enough to perfuse the brain
- arterial smooth muscle increases blood pressure by vasoconstricting - baroreceptors in aorta get stressed and results in bradycardia

Question 11

explain the mechanism of Cushings reflex

Answer 11

1. cerebral ischaemia - sympathetic NS - VC - hypertension
2. HTN - stresses baroreceptors - parasympathetic - bradycardia
3. HTN - pressure of resp centre - irregular breathing