Cerebral Infarction Flashcards
(34 cards)
Define stroke
Sudden onset of focal or global neurological symptoms cause by ischaemia or haemorrhage and lasting more than 24hrs
Define TIA
Term used if the symptoms resolve within 24 hours
Name six causes of an ischaemic stroke
- Large artery atherosclerosis
- Cardioembolic
- Small artery occlusion
- Undetermined/cryptogenic
Rare causes
• Arterial dissection
• Venous sinus thrombosis
Name three causes of haemorrhage stroke
• Primary intracerebral haemorrhage
• Secondary haemorrhage
o Subarachnoid haemorrhage
o Arteriovenous malformation
What are the two types of strokes?
Ischaemic and haemorrhagic
What is the incidence and impact of stroke?
- 150 000 new strokes/year in UK
- 67 000 deaths/year in UK
- Stroke risk increases with age
Name four non-modifiable risk factors for stroke
- Previous stroke
- Elderly
- Male
- Family history
Name six modifiable risk factors for stroke
• Hypertension
- Smoking
- Cholesterol
- Diet, high BMI, sedentary
- Alcohol
- Diabetes
How does hypertension impact risk of stroke?
- Stroke risk is related to blood pressure level
- Chronic hypertension worsens atheroma and affects small distal arteries
- Hypertension is a major risk factor for haemorrhagic strokes as well
How does smoking impact risk of stroke?
- 2-fold increase risk of cerebral infarction
* 3-fold increase risk of sub-arachnoid haemorrhage
How does diabetes impact risk of stroke?
Increases incidence of stroke up to 3-fold in both sexes.
How do lipids impact risk of stroke?
- Increase serum lipids increase stroke risk due to blood vessel wall atheroma
- Increase plasma level of low density lipoprotein (LDL) results in excessive amounts of LDL within the arterial wall
- Hypertension, cigarette smoke and diabetes contribute to LDL-C deposition in arterial walls
How does alcohol impact risk of stroke?
- Small amounts of alcohol decrease stroke risk
* Heavy drinking increase risk 25-fold
What are other risk factors?
- Impaired cardiac function – recent heart attack, atrial fibrillation
- Oral contraceptives (+hormone replacement therapy) with a high oestrogen content – progesterone-only are ok.
- Hypercoagulable states – malignancy, genetic
Describe the pathophysiology of ischaemic stroke
- Failure of the cerebral blood flow to a part of the brain, caused by an interruption of the blood supply to the brain
• Can be transient (as in TIA)
• Results in varying degrees of hypoxia - Hypoxia stresses the brain cell metabolism. This is especially important in the ischaemic penumbra. If prolonged, the hypoxia -> anoxia (no oxygen).
- Anoxia -> infarction (complete cell death, leading to necrosis). This is a stroke.
How does further damage occur after a stroke?
- Oedema – depending on the size + location of the stroke
* Secondary haemorrhage into the stroke
What three cerebral arteries form the anterior circulation of the brain?
- Internal carotid arteries
- Anterior cerebral artery (ACA)
- Middle cerebral artery (MCA)
What three cerebral arteries form the anterior circulation of the brain?
• 2 vertebral arteries -> 1 basilar
• 3 cerebellar arteries
Posterior cerebral artery (PCA
What are the effects of an anterior cerebral artery occlusion?
Contralateral
• Paralysis of foot and leg
• Sensory loss over foot and leg
• Impairment of gait and stance
What are the effects of a middle cerebral artery occlusion?
• Contralateral
o Paralysis of face/arm/leg
o Sensory loss face/arm/leg
o Homonymous hemianopia
• Gaze paralysis to the opposite side
• Aphasia if stroke on dominant (left) side
• Unilateral neglect and agnosia for half of external space if non-dominant stroke (usually right side)
What are the effects if an occlusion of the middle cerebral artery occlusion occurs in the right hemisphere?
Left hemiplegia, homonymous hemianopia
Neglect syndromes (agnosia): • Visual agnosia • Sensory agnosia • Anosagnosia (denial of hemiplegia) • Prosopagnosia (failure to recognise faces)
What type of stroke occurs if a branch of the MCA supplying basal ganglia is occluded?
Lacunar stroke
What are the symptoms of a lacunar stroke?
- Devoid of cortical signs – i.e. no dysphasia, neglect, hemianopia
- Pure motor stroke
- Pure sensory stroke
- Dysarthria – clumsy hand syndrome
- Ataxic hemiparesis
What structures are supplied by the posterior circulation?
- Brainstem
- Cerebellum
- Thalamus
- Occipital lobe
- Medial temporal lobe
