Acute stroke Flashcards
What percentage of total blood volume circulates through the brain, and at what rate?
20% of total blood volume at approximately 750mL/minute.
What is the definition of ischaemic stroke?
An episode of neurological dysfunction caused by focal cerebral, spinal, or retinal infarction.
What is the definition of stroke caused by intracerebral haemorrhage?
Rapidy developing clinical signs of neurological dysfunction attributable to a focal collection of blood within the brain parenchyma or ventricular system that is not caused by trauma
What is the definition of stroke caused by subarachnoid haemorrhage?
Rapidly developing signs of neurological dysfunction and/or headache because of bleeding into the subarachnoid space (space between the arachnoid membrance and the pia mater of the brain or spinal cord) which is not caused by trauma
What is the definition of stroke, not otherwise specified?
An episode of acute neurological dysfunction presumed to be caused by ischemia or haemorrhage, persisting 24 hours or more or until death, but without sufficient evidence to be classified as one of the above.
What is a transient ischaemic attack?
A neurological deficit that resolves, usually within 24 hours
How many TIAs progress to stroke?
One third
What percentage of strokes can be prevented?
More than 80%
Approximately ____% of acute strokes are ischaemic
80%
Approximately ____% of acute strokes are haemorrhagic
20%
Approximately 20% of ischaemic strokes are clots travelling from the ____.
Heart
Where does thrombus formation typically occur?
Origin or bifurcation of arteries
What are the causes of embolism?
- Vascular stasis (stenotic vessels, AF, MI, un-ruptured aneurysms)
- Thromboembolism
- Gas embolism
- Amniotic fluid embolism
- Fat embolism
What are the thrombotic risk factors?
- Hypertension
- Hyperlipidaemia
- Diabetes
- Smoking
- Obesity
- Systemic atherosclerosis
- Hypercoagulable states
What are the embolic risk factors?
- AF
- Endocarditis
- Dilated cardiomyopathy
- Recent MI
- Heart valve replacement
- Rheumatic heart disease
- Patent foramen ovale
What are the most severe strokes?
Large vessel occlusion
What percentage of haemorrhagic strokes are intracerebral?
15%
What percentage of haemorrhagic strokes are subarachnoid?
5%
What are the signs/symptoms of sub-arachnoid haemorrhage?
- Severe headache
- Hx of head trauma/lifting/straining
- 50% have mild headache hours/days prior that resolves with analgesia
- Upper neck pain
- Photophobia
- N+V not relieved with antiemetics
- Hypertension
- Bradycardia
What are the six types of cerebral herniation?
- Uncal
- Central
- Cingulate
- Transcalvarial
- Upward
- Tonsillar
What should any trauma with neck pain and neurological symptoms should lead you to suspect?
Arterial dissection
Describe the events leading up to aortic dissection
- Tear in the tunica intima
- Blood forces its way into the tear causing the intima to separate
- False lumen is created
- Weakened wall fails under pressure
What are the non-modifiable risk factors for stroke?
- Age
- Gender
- Family hx
What are the modifiable risk factors for stroke?
- TIAs
- Hypertension
- Smoking
- High cholesterol
- Poor diet
- Lack of exercise
- Obesity
- Diabetes
- Alcohol
- AF
What criteria does the QAS use for identifying stroke?
Modified MASS
What are the contraindications for acute stroke referral?
- Hx of serious systemic disease (advanced/terminal cancer, severe liver/kidney disease)
- Resident of an aged care facility requiring significant assistance with ADLs
- Symptoms suggestive of stroke in the setting of acute trauma
- Hx of seizures or epilepsy
- BGL <2.8 or >22.1
What would a differential diagnosis for acute stroke include?
- Intracranial space-occupying lesion
- Subdural haematoma
- Multiple sclerosis
- HI
- Hypoglycaemia
- Seizure disorders
- Complex migraine
What is the treatment window for thrombolysis?
4.5 hours
Endovascular clot removal benefits what kind of stroke patients?
Large vessel occlusion, out to 6 hours
