Transient Ischaemic Attack (TIA)

Question 1

What is the definition of a transient ischaemic attack?

Answer 1

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)

Question 2

How long do most TIAs last for?

Answer 2

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

Question 3

What type of scan can be used to identify damage caused as a result of TIA?

Answer 3

Diffusion-weighted MRI imaging shows areas of cytotoxic oedema

Question 4

How are the causes of TIA and stroke related?

Answer 4

The causes are the same

1. Carotid artery / large artery disease e.g. atherosclerosis
2. Cerebral small vessel disease
3. Cardiac embolism

Patients with TIA have the same vascular risk factors as stroke

e.g. diabetes, hypertension, high cholesterol, etc.

Question 5

If symptoms resolve within 24 hours, what type of scan should be conducted?

Answer 5

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

Question 6

Why is it important to identify a TIA and distinguish it from a stroke?

Answer 6

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

Question 7

How common are TIAs?

In one year, approximately how many cases would be seen by a GP?

Answer 7

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

Question 8

Why may a GP often suspect that they see more than 5 TIA cases in a year?

Answer 8

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

Question 9

What is meant by positive and negative symptoms?

Which line represents a TIA?

Answer 9

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

Question 10

What do lines A and B represent?

Answer 10

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

Question 11

What is Todd’s paresis?

Answer 11

Focal weakness in a part or all of the body after a seizure

It usually subsides within 48 hours

Question 12

What are the 5 main conditions which act as TIA mimics?

Answer 12

1. Seizures
2. Syncope
3. Hypoglycaemia
4. Migraine
5. Acute confusional states

Question 13

What symptoms of a migraine aura often lead it to becoming confused with a TIA?

Answer 13

If the content of the speech is abnormal i.e. words are strung together that don’t make sense (dysphasia)

slight facial asymmetry

Question 14

After confirming a TIA, what is the first part of the assessment?

Answer 14

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?

Question 15

What symptoms would you see if the TIA was in the anterior circulation?

Answer 15

1. Dysphasia
2. Amarausis fugax

this involves the internal carotid arteries

Question 16

What is amarausis fugax?

Which artery is implicated in order for this to be present?

Answer 16

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

Question 17

What types of symptoms would be present if the cause of TIA affected the posterior circulation?

Which vessels are involved?

Answer 17

Involves the vertebral arteries

these supply the brainstem, cerebellum and visual cortex

• ataxia
• diplopia
• vertigo
• bilateral symptoms

Question 18

What is ataxia?

Answer 18

a neurological sign consisting of lack of voluntary coordination of muscle movements that can include gait abnormality, speech changes, and abnormalities in eye movements

Question 19

What are the 3 signs / symptoms which can occur in a TIA in either the posterior or anterior circulation?

Answer 19

• Visual field disturbances (e.g. hemianopia)
• hemiparesis
• hemisensory loss

weakness or hemisensory loss pathways run from the anterior cerebral cortex, through the brainstem (posterior circulation), so you cannot distinguish which circulation is affected by these symptoms

Question 20

What is hemianopia?

Answer 20

Blindness over half the field of vision

Question 21

What is meant by hemiparesis and hemisensory loss?

Answer 21

Hemiparesis:

• weakness of one entire side of the body

Hemisensory loss:

• loss of sensation on one side of the entire body

Question 22

How does having a TIA influence risk of having a stroke?

Answer 22

Patients who have had a TIA are at high risk of having a stroke within a few days

Question 23

What tool is used to work out the risk of stroke following TIA?

Answer 23

ABCD² Score for TIA

Age - 1 if over 60

Blood pressure - 1 if over 140/90

Clinical features - 2 if unilateral weakness, 1 if speech disturbance

Duration of symptoms - 2 if > 60 mins, 1 if 10-59 mins, 0 if < 10 mins

Diabetes - 1 if yes, 0 if no

Question 24

What does the ABCD² score tell you about the risk of stroke?

Answer 24

Low risk is < 4

Moderate risk is 4 or 5

High risk is > 5

Question 25

Why should you not rely on ABCD2 score to diagnose TIA or minor stroke?

Answer 25

This is a prognostic tool and not a diagnostic tool You may have a high ABCD2 score and not have a stroke or TIA Someone with a TIA may have a lower ABCD2 score

Question 26

How reliable is the ABCD2 score in clinical practice?

Answer 26

There is a margin for error as some people may do it wrong or may misclassify a symptom

Question 27

What are the stroke guidelines? What do they suggest about use of ABCD2 score and referring patients with suspected TIA?

Answer 27

Patients with suspected TIA should have a full diagnostic assessment urgently (\<24 hours) without further risk stratification patients presenting with symptoms more than a week ago are considered at lower risk ABCD2 score is falling out of favour and a patient with suspected TIA or minor stroke should be referred urgently

Question 28

What tests are involved in investigating a TIA?

Answer 28

1. History 2. Examination - particularly cardiovascular 3. Cardiovascular tests - ECG, blood tests, echo 4. Blood glucose 5. Brain imaging to distinguish between TIA and TIA mimic

Question 29

What types of medication are given in medical secondary prevention to reduce stroke risk?

Answer 29

1. Aspirin and/or clopidogrel 2. Statins 3. Blood pressure treatment they are given for the rest of the patient's life 4. Warfarin or anticoagulant is given if atrial fibrillation is present These factors all have an additive effect

Question 30

What is meant by the 'polypill'? Why would it be used?

Answer 30

A combination of: 1. Statin 2. Aspirin 3. Antihypertensives 4. Folic acid these are suspected to reduce vascular events by 80% it improves patient compliance by only needing to take a single pill

Question 31

When is a carotid endarterectomy used as a mechanism of secondary vascular prevention?

Answer 31

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

Question 32

What are the complications associated with carotid endarterectomy?

Answer 32

* There is a 3 - 5% risk of stroke / death during surgery * nerve palsy of superior laryngeal / hypoglossal / greater auricular nerve these are located close to the carotid artery in the neck can lead to pain, hoarse voice and damage to the lower cranial nerves

Question 33

When should the carotid endarterectomy be performed in order to be effective in preventing further strokes?

Answer 33

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

Question 34

What types of medications should be given following TIA to reduce stroke risk?

Answer 34

* 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

Question 35

What is worse: a carotid artery being 75% or 100% blocked? Why?

Answer 35

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