Strokes/TIA Flashcards
Definition
sudden onset of neuroloigcal deficits due to loss of circulation to the brain resulting in an infarction or haemorrhage
Different types of strokes
TIA (mini stroke)
Ischaemic strokes (80%):
– cerebral thrombosis
– cerebral embolism
– hypoperfusion
– small vessel disease
– large artery stenosis
Cerebral haemorrhage (17%) most serious type of stroke
Other (3%):
– arterial dissection
– venous sinus thrombosis
– vasculitis
TIA
Otherwise known as a mini stroke
– where there is temporary loss of blood flow to the brain causing a temporary brain perfusion
– to be classed as a TIA, the symptoms have to go within 24 hours
– usually lasts 10-20 mins and rarely goes up to 24 hours
Pathophysiology:
– temporary reduction of the cerebral blood flow
– carotid stenosis/atherosclerosis may cause thrombus/emboli that may temporarily block the blood flow to the brain
– atherosclerosis may increase the likelihood
Prevalence:
– 2% of adult population aged 55-65
– 5% of the population over the age of 85
– male 2:1 female
– black and Hispanic men have higher risk
Symptoms:
– variable depending on region of the brain involved
– may complain of sudden severe headache
– sudden short duration numbness in face or limbs, particularly down one side of the body, possible drop attack (sudden leg weakness)
– confusion, trouble talking or understanding conversations
– brief changes in vision
– TIA can cause an episode of amaurosis fujax
Imaging:
– CT
– diagnostic ultrasound
– angiography
TIA;s can lead to micro-infarctions, where tiny amounts of brain tissue due leaving microscopic infarctions.
– Common in older people, and over time the repeated loss of small amounts of neural tissue is cumulative and can lead to dementia (multiple infarction dementia).
– may be a forerunner for a more serious type of stroke
Ischaemic stroke
Cerebral thrombosis:
type of ischaemic stroke (80%) of all strokes
– strokes caused by a thrombus that develops in the arteries leading to the stoppage of blood flow to the brain
RF:
– atherosclerotic changes and things that can cause that
– virchows triad
– pregnancy
Carotid and vertebral artery dissection:
– accounts for around 1 in 5 strokes below the age of 40
– Genetic predisposition, neck manipulation,
Venous stroke:
– only 1% of strokes are venous
Epidemiology of strokes (not TIA)
incidence- 130/100’000
age- increased risk with age over 45 (highest risk in 60s and 70s)
Gender- men 3x more likely than women. (evens out after the menopause)
Genetics- positive family history of stroke can increase risk up to 30%
Cerebral embolism
Most common type of embolic stroke. where a thrombus in another part of the body moves up to the brain as an emboli to block the blood flow to the brain
– very rare complication of DVT (only if there is an atrial septal deviation).
RF:
– common in patients with atrial fibrillation
– emboli may be secondary to mitral valve pathology
– there may be increased risk with small vessel diseases (diabetes and hypertension)
Cerebral haemorrhage
Most severe type of stroke- occurs when the blood vessel in the brain ruptures, allowing blood to leak and causing damage to an area of the brain (raising intracranial pressure, killing the brain cells)
30 day mortality rate 40-80%
50% of all deaths occur within the first 48 hours
2 subtypes:
– intracranial haemorrhage (more common)- bleeding within the brain tissue itself
– subarachnoid haemorrhage- occurs in the space around the brain
RF:
– major risk is hypertension, as it places the cerebral arteries under more pressure
– can cause a weakening of the aortic wall leading to an aneurysm (berry aneurysm is seen in the brain)
Astrocytes and the blood brain barrier:
– most of the smaller blood vessels of the cerebral circulation are developed by neuroglial cells called astrocytes
– astrocytes form the blood brain barrier:
—- when a cerebral haemorrhage occurs, the BBB is breached so toxic materials such as urea, uric acid etc within the blood can damage the neural tissue within the brain
—— this inflicts widespread damage
Areas strokes can occur in the brain
Any region can be affected by any type of stroke
Brain stem (10% of strokes)
– midbrain, pons and medulla
– home to vital centres like the cardiac, respiratory and the vasomotor centres
– if these are damaged during the stroke and the treatment isn’t imminent, then the chances of survival are low
– locked in syndrome:
– where the pt is aware of what is going on around them but isnt able to communicate
Cerebellum:
– 3-5% of all strokes
– plays an important role in balance and coordinated movement, also speech
Cerebral hemispheres:
– over 80%.
– present contralaterally
– depending on the symptoms depends on what lobes have been damaged
– frontal lobe (somatomotor cortex)
—- hemiplegia
– parietal lobe (somatosensory cortex)
—- hemiparasthesia
– occipital lobe (visual cortex)
—- loss of vision
—- cortical blindness (blindness that results from a CVA)
– temporal lobes (auditory cortex), essential to visual memory or long term memory function
—- amnesia, personality changes etc
Symptoms of a stroke in general
Sudden appearance of symptoms
Sudden numbness in face or limbs, particularly down one side of the body
Confusion, trouble talking or understanding conversation or verbal instruction
Trouble walking or maintaining balance
Seizures or loss of consciousness can occur but are VERY RARE
