2. Strokes - TIA, Ischaemic + Haemorrhagic Flashcards
What is the definition of TIA?
Transient Ischaemic Attack.
A brief episode of transient neurological dysfunction due to temporary focal cerebral ischaemia without infarction.
What is a crescendo TIA?
A crescendo TIA is where there are 2 or more TIAs within a week.
-> Carries a high risk of developing in to a stroke.
What is the duration of symptoms in a TIA? How long do these symptoms last in a TIA?
Symptoms are maximal at onset:
-> Usually last 5-15 minutes
Classical definition: lasts <24 hours.
Without intervention, 1 in 12 have a stroke within a week.
Explain the pathophysiology of TIA.
- Cerebral ischaemia
- Lack of oxygen + nutrients to the brain
- Cerebral dysfunction
- In TIA: period of ischaemia = short-lived
= Ischaemia without infarction (the tissue does not die)
What is the main cause of TIA?
Atherothromboembolism from the carotid artery
(listen for the carotid bruit!)
Other than atherothromboembolism, name 3 other causes of TIA.
- Cardioembolism
- In Atrial Fibrillation
- After an MI
2, Valve disease/prosthetic valve
- Hyperviscosity
- Polycythaemia
- Sickle cell anaemia
- Extremely raised white cell count
- Myeloma - Hypoperfusion
- Cardiac dysrhythmia
- Postural hypotension
- Decreased flow through atheromatous arteries
Name 5 risk factors for TIA.
Risk factors:
- Age - risk increases with age
- Hypertension
- Smoking
- Diabetes
- Obesity
- High alcohol intake
- Heart disease - valvular, ischaemic or atrial fibrillation
- Past TIA
- Raised packed cell volume (PCV)
- Peripheral arterial disease
- Polycythaemia vera
- Combined oral contraceptive pill (since increase risk of clots)
- Hyperlipidaemia
- Clotting disorder
- Vasculitis e.g. SLE, giant cell arteritis is rare risk factor
Describe the epidemiology of TIA.
- 15% of first strokes are preceded by TIA, they are also a foreshadowing of an MI.
- More common in MALES than females (M > F).
- Black ethnicity are at greater risk due to their hypertension and
atherosclerosis predisposition.
For the clinical presentation of a TIA, the features be categorised based on what?
Site of the TIA - the arterial territories affected:
- Carotid artery (anterior circulation) - 90% of TIAs
- Vertebrobasilar artery (posterior circulation) - 10% of TIAs
For a TIA affecting the carotid artery and the anterior circulation, describe the clinical presentation.
- Hemiparesis
- Weakness on an entire side of the body - Hemisensory loss
- Hemianopic visual loss
- Aphasia/Dysphagia
- Loss of language - Amaurosis fugax
- Sudden transient loss of vision in one eye
The occurrence of which symptom in TIA is often the first clinical evidence of an ICA stenosis?
Amaurosis fugax (sudden transient loss of vision in 1 eye)
What is amaurosis fugax and what causes it?
Sudden transient loss of vision in 1 eye (unilateral).
Occurs due to the temporary reduction in the retinal, opthalmic or ciliary blood flow, leading to a temporal occlusion, leading to temporary retinal hypoxia.
“Like a curtain descending.”
For a TIA affecting the vertebrobasilar artery and the posterior circulation, describe the clinical presentation.
- Diplopia (double vision), vertigo, vomiting
- Choking & dysarthria (unclear articulation of speech but
understandable) - Ataxia - no control of body movement
- Hemisensory loss
- Hemianopia vision loss
- Tetraparesis
- Muscle weakness affecting all 4 extremities - Loss of consciousness (rare)
What symptoms that occur on their own do not imply a TIA?
NOT a TIA if these occur on their own:
- Syncope
- Dizziness
- Temporary loss of consciousness
- Temporary memory loss
Gradual onset – suggests demyelination, tumour, migraine
Investigations for a TIA.
- Often solely based on its description
- Bloods:
* FBC - look for polycythaemia
* ESR - will be raised in vasculitis
* Glucose - to see if hypoglycaemic
* U+Es
* Cholesterol
* INR (prothombin time) - if on warfarin - Carotid artery doppler ultrasound
-> to look for stenosis/atheroma - Then: MR/CT angiography
-> if stenosis: to determine extent - Brain imaging: diffusion weighted CT / MRI
-> if stenosis: to determine extent - ECG:
-> Look for AF or evidence of MI ischaemia - Echocardiogram/cardiac monitoring
-> to assess for a cardiac cause
What is essential to do in someone who has had a TIA?
Assess their risk of having a stroke in the next 7 days - ABCD2 score.
What is the ABCD2 score?
It is used in patients who have had TIA’s to assess their risk of stroke in the next 7 days.
- Age > 60. (1 point)
- BP > 140/90 mmHg. (1 point)
- Clinical features: unilateral weakness (2 points), speech disturbance (1 point)
- Duration of symptoms: > 1h or 10-59 mins. (10 mins+ = 1; 1h+ = 2)
- Diabetes?
If more than 6 -> refer patient specialist immediately
If more than 4 -> assessed by specialist within 24hr
What specific investigation would you carry out if you suspected that atherosclerosis had caused your patient’s TIA?
Carotid artery Doppler ultrasound.
Then: MR/CT angiography.
Name 3 differential diagnoses of a TIA.
Until there is a full recovery, it is IMPOSSIBLE to differentiate from a stroke.
- Hypoglycaemia
- Migraine aura
- Focal epilepsy
- Vaculitis
- Syncope
- e.g. due to arrhythmia - Retinal bleed
What is the immediate management of a TIA?
- Immediate loading dose: Aspirin 300mg
-> For 2 weeks
-> Then lower dose - Refer to specialist – to be seen within 24h of symptom onset.
What is the long term treatment for a TIA?
- Antiplatelet therapy
- Standard treatment is Aspirin 75mg daily
- With modified-release Dipyridamole
- OR Clopidogrel daily - Anticoagulation
- e.g. Warfarin
- For patients with Atrial Fibrillation - Statins
- e.g. Simvastatin - Control CV risk factors
- Antihypertensives e.g. ACEi (Ramipril) or ARBs (Candesartan)
- Improve diet, stop smoking - No driving for at least 4 weeks after a TIA
How does warfarin work to reduce platelet aggregation?
Inhibits vitamin K dependent synthesis of clotting factors 2, 7, 9 and 10
What is the surgical treatment for a TIA?
- Endarterectomy if 70% or more stenosis
-> Reduces stroke/TIA risk by 75% - Stent e.g. carotid stent
At what point, do symptoms become a stroke rather than a TIA?
If they last over 24h.