Transient Ischaemic Attack (TIA) Flashcards
What is the definition of a transient ischaemic attack?
Neurological deficit lasting less than 24 hours attributable to cerebral or retinal ischaemia
(there is a reduced blood supply to both the brain and the retina)
How long do most TIAs last for?
Most TIAs only last for a few minutes
The vast majority last for under 60 minutes
A TIA can sometimes be associated with brain damage, even if the symptoms only last for 5-10 minutes
What type of scan can be used to identify damage caused as a result of TIA?
Diffusion-weighted MRI imaging shows areas of cytotoxic oedema
How are the causes of TIA and stroke related?
The causes are the same
- Carotid artery / large artery disease e.g. atherosclerosis
- Cerebral small vessel disease
- Cardiac embolism
Patients with TIA have the same vascular risk factors as stroke
e.g. diabetes, hypertension, high cholesterol, etc.
If symptoms resolve within 24 hours, what type of scan should be conducted?
If symptoms resolve within 24 hours, you can be certain that there is not a bleed so a scan is not needed
the only way to distinguish between haemorrhage and infarct is a CT brain scan
Why is it important to identify a TIA and distinguish it from a stroke?
TIAs represent a window of opportunity to treat
20% of strokes are preceded by a TIA
If someone has a TIA, there is an opportunity to try and prevent stroke
How common are TIAs?
In one year, approximately how many cases would be seen by a GP?
The incidence is 50 / 100,000 population
this mirrors the incidence of stroke
on average, a GP will see 5 TIA cases in a year
Why may a GP often suspect that they see more than 5 TIA cases in a year?
TIAs can overlap with other conditions
more common conditions which are seen in clinic may be a TIA mimic
these conditions mimic TIA symptoms, but are not actually a TIA
What is meant by positive and negative symptoms?
Which line represents a TIA?
Positive symptoms include tingling, flashing lights, etc. - things that aren’t actually present
negative symptoms include loss of movement, vision etc.
Line C represents a TIA
it comes on suddenly and is associated with loss of function (negative symptoms)
it lasts a few minutes and then symptoms improve
What do lines A and B represent?
A - migraine with aura:
- both positive and negative symptoms
- they start gradually and fluctuate
B - epilepsy / seizure:
- sudden onset
- starts with positive symptoms, such as limb shaking
- this subsides and then there are negative symptoms - e.g. unable to move arms
- This is Todd’s paresis
What is Todd’s paresis?
Focal weakness in a part or all of the body after a seizure
It usually subsides within 48 hours
What are the 5 main conditions which act as TIA mimics?
- Seizures
- Syncope
- Hypoglycaemia
- Migraine
- Acute confusional states
What symptoms of a migraine aura often lead it to becoming confused with a TIA?
If the content of the speech is abnormal i.e. words are strung together that don’t make sense (dysphasia)
slight facial asymmetry
After confirming a TIA, what is the first part of the assessment?
Working out which part of the brain or vascular territory that the event has occurred in
i.e. Is it in the anterior or posterior circulation?
What symptoms would you see if the TIA was in the anterior circulation?
- Dysphasia
- Amarausis fugax
this involves the internal carotid arteries
What is amarausis fugax?
Which artery is implicated in order for this to be present?
The opthalmic artery, which is a branch of the internal carotid artery
this is ischaemia of the retina
patients complain of seeing a veil coming down over their eye
altitudinal field defect - the patient cannot see above and/or below horizontal
What types of symptoms would be present if the cause of TIA affected the posterior circulation?
Which vessels are involved?
Involves the vertebral arteries
these supply the brainstem, cerebellum and visual cortex
- ataxia
- diplopia
- vertigo
- bilateral symptoms
How does having a TIA influence risk of having a stroke?
Patients who have had a TIA are at high risk of having a stroke within a few days
What does the ABCD2 score tell you about the risk of stroke?
Low risk is < 4
Moderate risk is 4 or 5
High risk is > 5
How reliable is the ABCD2 score in clinical practice?
There is a margin for error as some people may do it wrong or may misclassify a symptom
What types of medication are given in medical secondary prevention to reduce stroke risk?
- Aspirin and/or clopidogrel
- Statins
- Blood pressure treatment
they are given for the rest of the patient’s life
- Warfarin or anticoagulant is given if atrial fibrillation is present
These factors all have an additive effect
When is a carotid endarterectomy used as a mechanism of secondary vascular prevention?
For carotid territory TIA above ICA stenosis > 70%
this involves surgical removal of a clot within the internal carotid artery to reduce the risk of stroke in that vascular territory
When should the carotid endarterectomy be performed in order to be effective in preventing further strokes?
An early carotid endarterectomy is more effective in preventing further strokes
you need to operate on patients close to the time they had a TIA (within 0 - 2 weeks)
if you wait for 3 months after the TIA, there is no benefit to having the surgery
they are unlikely to have a stroke and you are exposing them to potentially dangerous surgery
What types of medications should be given following TIA to reduce stroke risk?
- Aspirin +/- clopidogrel
- blood pressure lowering medication
- statin
- tests
- carotid surgery
immediate medial management can reduce subsequent stroke risk by 80%
treatment should be started within days or hours of the initial event
What is worse:
a carotid artery being 75% or 100% blocked?
Why?
An artery being 75% blocked is WORSE than the artery being 100% blocked
if an artery is completely blocked, they must have a strong collateral supply (circle of Willis) in order to survive
once the artery is blocked, no more clots can pass through the blockage
in a 75% blockage, clots can develop and travel elsewhere, increasing risk of stroke
