Transient Ischaemic Attack – a medical emergency
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Key Reviewer: Dr Edward Wong, Stroke Neurologist, Middlemore Hospital and Auckland City Hospital, Auckland
TIA is a warning
In one in four people a transient ischaemic attack (TIA) is a forerunner for a stroke,2,3 most of which occur in the first few days after a TIA.4 Emergency referral for high-risk patients, urgent investigations and prompt treatment may prevent these strokes from occurring.
85% of strokes that follow a TIA will be fatal or disabling.5 People with TIAs are also at high risk of non-stroke cardiovascular events e.g. myocardial infarction.
There are several effective interventions for preventing stroke and other cardiovascular events following a TIA. Rapid diagnostic workup, appropriate early interventions such as carotid endarterectomy and commencement of secondary prevention have shown significant reduction in the 90 day risk of stroke following TIA (approximately 80% relative risk reduction).6
Guidelines for managing TIA and stroke may not be applicable to people with severe co-morbidities or a terminal illness but for most people the aim is to identify a TIA, start antiplatelet therapy and refer.
A TIA may be thought of as a small stroke and shares similar signs and symptoms (Table 1):
- Rapid onset of symptoms – usually the patient or witness is certain when the event started
- Maximal neurological deficit at onset – progressive symptoms imply other diagnoses
- Focal symptoms typical of loss of blood supply to part of the brain
- Negative neurological symptoms (loss of function e.g. paralysis, weakness)
Most TIAs resolve within 60 minutes
Traditionally a TIA is defined as stroke signs and symptoms that resolve within 24 hours. However modern brain imaging now shows that most transient symptoms that last for more than one hour, are associated with detectable brain damage, and are in fact small strokes.
The clinical implications are that if symptoms are still present beyond one hour, then it can be assumed that this is likely to be a stroke.
|Table 1: TIA symptoms (Adapted from NZ TIA Guideline 2008)7|
|Symptoms typical of TIA||Symptoms not typical of TIA*|
Unilateral altered sensation
Dysphasia (speech deficit)
|Generalised weakness or sensory symptoms
Confusion (exclude dysphasia)
Impaired consciousness or syncope
Dizziness or light headedness
Incontinence – bladder or bowel
Bilateral blurred vision or scintillating scotoma
*If symptoms occur in isolation, without typical symptoms
|Note – ataxia, vertigo, dysphagia, dysarthria and sensory symptoms to part of one limb or the face may be consistent with TIA if they occur in conjunction with other typical symptoms|
The history of the event is crucial in making a diagnosis as often focal neurological signs have resolved by the time the patient presents. A witness’s account can be invaluable.
A quick screening tool to aid the diagnosis of stroke or TIA is Face Arm Speech Test (FAST).1 This may be performed on examination or retrospectively on history if the symptoms have resolved.
If time permits, further neurological examination to assess gaze and visual fields, limb ataxia and any sensory signs may be appropriate.
Likewise cardiovascular examination may be helpful to identify known risk factors:
- Neck bruit
- Atrial fibrillation
- Raised blood pressure
- Reduced or absent peripheral pulses
- Heart murmurs
|If possible check blood glucose. If <3.5 mmol/L treat and reassess once blood glucose is normal.|
FACIAL WEAKNESS – Can the patient smile?Ask patient to smile or show teeth.
ARM WEAKNESS – Can the person raise both arms?Lift the patient’s arms together at 90 degrees if sitting, or 45 degrees if supine, and ask them to hold in position for five seconds. Then let go.
SPEECH PROBLEMS – Can the person speak clearly?If the patient attempts conversation.
TIME TO REFERIf there is any neurological deficit, consistent with stroke or TIA, do not delay: Arrange to transfer the patient acutely to secondary care.
Step 1 – Medication
For those people with suspected TIA and no neurological deficit on examination, start aspirin (300 mg stat, and then 75–100 mg daily) if tolerated.8
If the patient is already on aspirin, special authority may be applied for to add dipyridamole.
Blood pressure reduction in the acute phase (prior to diagnosis being confirmed) is not recommended.
Step 2 – Speed of referral based on stroke risk
Urgency of referral depends on the stroke risk. This can be assessed with the ABCD2 tool.9,10
High risk (≥4) – very rapid referral within 24 hours
ABCD2 scores of four and above are associated with higher likelihood of a true diagnosis of TIA and high risk of subsequent stroke (3.5% at two days and 5% at seven days.11 Other high-risk patients include those with; symptoms at the time of assessment, more than one TIA in a week (crescendo TIAs), atrial fibrillation or those taking warfarin. High-risk patients require urgent assessment at a specialist centre, with access to brain and carotid imaging, within 24 hours of onset of symptoms.12
Low risk (≤3) – urgent referral within seven days
ABCD2 scores of three or less have a lower risk of stroke. These patients, plus those with higher scores but presenting more than one week following the TIA, may initially be managed in the community followed by specialist assessment and investigations within seven days of onset of symptoms. If the treating doctor is certain of the diagnosis, confident of initiating treatment and has ready access to brain and carotid imaging then specialist review may not be required.
|ABCD2 – prediction of stroke risk after TIA|
|ABCD2 items (score: 0–7)||Points|
|A||Age: ≥ 60 years||1|
|B||Blood Pressure: ≥ 140/90mm Hg||1|
|unilateral weakness or||2|
|speech impairment without weakness||1|
|D||Duration of symptoms:|
|≥ 60 minutes or||2|
|D||Diabetes: on medication/insulin||1|
Specialist review will confirm a diagnosis of TIA in approximately 50–80% of patients referred from the community.13
Initial investigations of TIA in primary or secondary care should include CBC, electrolytes, creatinine, fasting lipids, CRP, ESR (to rule out temporal arteritis) random glucose, INR (if on warfarin) and ECG.
Other possible investigations, usually performed in secondary care, are echocardiology, angiography, CXR, syphilis serology, vasculitis screen (ANA) and prothombotic screen (aPTT, PT).
Since TIA is a clinical diagnosis investigations include brain imaging to confirm cerebral ischaemia or haemorrhage and to exclude stroke mimics. Brain imaging is mandatory, to exclude intracranial haemorrhage as the cause of the current event, prior to commencing warfarin for atrial fibrillation.
Carotid imaging is appropriate in people, with carotid circulation symptoms (Table 2) who are fit for surgery. Urgent endarterectomy may be recommended for people with symptomatic severe stenosis of the internal carotid artery.
|Table 2: Carotid and vertebrobasilar TIA symptoms|
|Carotid TIA||Vertebrobasilar TIA|
Step 3 – Begin early treatment as soon as TIA confirmed
As soon as a diagnosis of TIA is confirmed by a specialist, preventive measures to modify risk should be commenced. Antiplatelet and statin therapy should continue.
All patients should be offered information and personalised advice about how they can reduce their modifiable risks.19 Any co-morbidities such as atrial fibrillation, diabetes, hypercholesterolaemia and hypertension should be intensively treated20 (Table 3).
Secondary prevention to modify risk factors can reduce the risk of stroke by up to 80%.21
|Table 3: Modifiable risk factors for stroke following a TIA (excluding carotid endarterectomy). Adapted from LaRocque et al, 2008.14|
|Lifestyle factors||Smoking||Smoking doubles stroke risk. All people who smoke should be strongly encouraged to stop immediately. (see BPJ 10 and smoking cessation guidelines)|
|Alcohol||Avoid excessive alcohol: no more than two drinks/day for men and one drink/day for women.|
|Body mass index||Encourage weight loss in those who are overweight. Aim for BMI of <25 kg/m2 and waist circumference of <100 cm in men and <90 cm in women.|
|Diet||Encourage a low fat, low sodium diet with 5+ portions a day of fruit and vegetables.|
|Physical activity||Encourage an increase in physical activity to regular exercise 30–60 minutes most days of the week.|
|Medical therapies||Blood pressure lowering||Even small decrease in blood pressure reduces stroke risk by 20–25%. All people, whether normotensive or hypertensive should start antihypertensives within the first week, if tolerated. No specific blood pressure target can be recommended for all people.|
|First-line ACE inhibitor +/– thiazide diuretic.|
|Long term antiplatelet therapy should be prescribed to all people who are not on an anticoagulant.|
|First-line aspirin plus modified release dipyridamole16 (currently dipyridamole is only subsidised if a person continues to have TIAs while on aspirin, however this restriction is currently under review).|
|Second-line aspirin or clopidogrel alone (not currently subsided for non-aspirin allergic patients).|
|Should be used in all people who have atrial fibrillation, cardioembolic stroke from valvular heart disease or recent myocardial infarction once brain imaging has excluded intracranial haemorrhage.|
|Cholesterol lowering||Statins should be prescribed for all people able to tolerate therapy. Aim for LDL <2.5 mmol/L.|
|Diabetes management||Check for diabetes and manage in–line with national guidelines.18|
There is a wide differential diagnosis for a patient who presents with a history of transient neurological symptoms. Symptoms that make the diagnosis less likely are:
- Positive neurological symptoms – such as pins and needles, limb shaking or scintillating visual field abnormalities
- Global symptoms – such as confusion, faints, generalised numbness, bilateral blurred vision, isolated dizziness
Differential diagnoses of TIA:7
- Migraine aura, with or without headache
- Hypotension and/or syncope
- Transient episodes of non focal symptoms e.g. confusion
- Peripheral vestibular disorders – isolated vertigo that may have associated nausea and ataxia
- Partial (focal) epileptic seizures
- Anxiety and/or hyperventilation
- Transient global amnesia
- Drop attacks – sudden transient loss of postural tone causing falls
In general driving is not safe in the early days and weeks after a TIA because of the significant risk of a stroke.
The Land Transport and Safety Agency recommend:
- Private licence: no driving for minimum of one month
- Commercial licence: no driving for minimum of six months and then specialist review.
More than one TIA
- Private licence: no driving for minimum of three months and return only if cause adequately investigated and treated.
- Commercial licence: no driving. Appeal possible with specialist support.
- Stroke Foundation of New Zealand TIA guideline 2008. www.stroke.org.nz
- New Zealand Guidelines Group. New Zealand smoking cessation guidelines, 2007. www.nzgg.org.nz
- New Zealand Guidelines Group. Assessment and management of cardiovascular risk, 2003. www.nzgg.org.nz
- New Zealand Guidelines Group. Management of type 2 diabetes, 2003. www.nzgg.org.nz
- Land Transport Safety Authority. New Zealand Medical fitness to drive, 2002. www.ltsa.govt.nz/licensing/docs/ltsa-medical-aspects.pdf
- National Collaborating Centre for Chronic Conditions. Stroke: National clinical guideline for diagnosis and initial management of acute stroke and transient ischaemic attack (TIA). London: Royal College of Physicians, 2008. Available from http://www.nice.org.uk/CG068 (accessed January, 2009).
- Wu CM, McLaughlin K, Lorenzetti DL, et al. Early risk of stroke after transient ischemic attack: a systematic review and meta-analysis. Arch Intern Med 2007; 167(22):2417-22.
- Giles MF, Rothwell PM. Prognosis and management in the first few days after a transient ischaemic attack or minor ischaemic stroke. Int J Stroke 2006;1:65-73.
- Coull A, LovettJK, Rothwell PM et al. Early risk of stroke after a TIA or minor stroke in a population-based incidence study. BMJ 2004;328:326-8.
- Johnston SC, Gress DR, Browner WS et al. Short-term prognosis after emergency department diagnosis of TIA. JAMA 2000;284:2901-6.
- Rothwell PM, Giles MF, Chandratheva A et al. Effect of ugent treatment of transient ischaemic attack and minor stroke on early recurent stroke (EXPRESS study): a prospective population-based sequential comparison. Lancet 2007;370(9596):1432-43.
- Stroke Foundation of New Zealand. NZ Guidelines for the Assessment and Management of Transient Ischaemic Attack (TIA). 2008. Available from www.stroke.org.nz (accessed January, 2009).
- Sandercook PAG , Counsell C, Gubitz GJ, Tseng M-C. Antiplatelet therapy for acute ischaemic stroke. Cochrane Database Syst Rev 2008;4:CD000029.
- Johston SC, Rothwell PM, Nguyen-Huynh MN, et al. Validation and refinement of scores to predict very early stroke risk after transient ischaemic attack. Lancet 2007;369(9558):283-92.
- Giles MF, Rothwell PM. Risk prediction after TIA: the ABCD system and other methods. Geriatrics 2008;63(10):10-16.
- Josephson SA, Sidney S, Pham TN, et al. Higher ABCD2 score predicts patients most likely to have true transient ischaemic attack. Stroke 2008;49:3096-8.
- Franklin M, McDiarmid T, Mackler L. Clinical Inquiries: Is an outpatient workup safe for patients with a transient ischaemic attack? J Fam Prac 2004;53(7):567- 9.
- Lavallee PC, Mesequer E, Abboud H, et al. A transient ischaemic attack clinic with round the clock access (SOS-TIA): feasibility and effects. Lancet Neurol 2007;6(11):953-60.
- LaRocque P, McBride P. Prevention of secondary stroke/transient ischaemic attack. CME Bulletin, American Academy of Family Physicians 2008;9(5):1-5.
- Kirshner HS. Prevention of secondary stroke and transient ischaemic attack with antiplatelet therapy: the role of the primary care physician. Int J Clin Pract 2007;61(10):1739-48.
- ESPRIT Study Group: Halkes PH et al. Aspirin plus dipyridamole versus aspirin alone after cerebral ischaemia of arterial origin (ESPRIT): randomised controlled trial. Lancet 2006;367(9523):1665-73.
- Sandercock PAG, Counsell C, Karmal AK. Anticoagulants for acute ischaemic stroke. Cochrane Database Syst Rev 2008;4:CD000024.
- New Zealand Guidelines Group. Management of type 2 diabetes. 2003. Available from www.nzgg.org.nz (accessed January 2009).
- Miller ET, Spilker J. Readiness to change and brief educational interventions: successful strategies to reduce stroke risk. J Neuro Nurs 2003;35(4):215-22.
- Lip GYH, Kalra L. Stroke prevention. BMJ Clinical Evidence 2008;9:207.
- Hackman DG, Spence JD. Combining multiple approaches for the secondary prevention of vascular events after stroke: a quantitative modeling study. Stroke 2007;38:1881-5.