TIAs Flashcards
What is a TIA?
A transient ischaemic attack (TIA) is a temporary inadequacy of the circulation in part of the brain (a cerebral or retinal deficit) that gives a clinical picture similar to a stroke except that it is transient and reversible
What is the time cut-off for TIAs?
The duration is no more than 24 hours and a deficit that lasts longer than 24 hours is defined as a stroke.
How long does the majority of TIAs last?
30 minutes
What is a crescendo TIA?
A crescendo TIA refers to two or more episodes of TIA within a week and usually requires urgent specialist evaluation.
What are the risk factors for TIAs?
Hypertension. Smoking. Diabetes mellitus. Heart disease (valvular, ischaemic, atrial fibrillation). Peripheral arterial disease. Polycythaemia vera. Carotid artery occlusion; carotid bruit. Combined oral contraceptive pill. Hyperlipidaemia. Excess alcohol. Clotting disorders.
What is the aetiology of TIAs?
It is usually embolic, may be thrombotic, and occasionally haemorrhagic (unlikely to produce a reversible lesion).
The most common source of emboli is the carotids, usually at the bifurcation.
They can originate in the heart with atrial fibrillation particularly, with mitral valve disease, or aortic valve disease, or from a mural thrombus forming on a myocardial infarct or a cardiac tumour - usually atrial myxoma.
The vertebrobasilar arteries may be a source.
Occasionally there is paradoxical embolism originating from the right side of the circulation.
What should be done in primary care for a patient presenting with a TIA?
A validated tool such as FAST (Face Arm Speech Test) should be used in primary care to screen people with sudden onset of neurological symptoms.
Exclude hypoglycaemia as a cause of these symptoms.
Any person presenting with acute neurological symptoms that resolve completely within 24 hours (i.e. suspected TIA) should be started on aspirin 300 mg, with the first dose given immediately (unless contra-indicated).
Any person presenting with a suspected TIA should be referred immediately and assessed urgently within 24 hours by a specialist physician in a neurovascular clinic or an acute stroke unit.
Scoring systems such as ABCD2 should not be used to inform urgency of referral.
Secondary prevention in addition to aspirin should be offered as soon as possible.
How does TIAs present if the ischaemic event is present in the carotid territory?
Symptoms are usually unilateral and most often affect the motor area, causing unilateral weakness, affecting an arm, leg, or one side of the face. There may be dysarthria.
There may be sensory symptoms in the same areas.
If Broca’s area is involved, there will also be difficulty with speech - called Broca’s dysphasia. This produces inconsistent and unpredictable errors, usually substitution, with spontaneous speech containing fewer errors
There may be amaurosis fugax (fleeting loss of vision), a unilateral loss indicative of retinal ischaemia, usually associated with emboli or stenosis of the ipsilateral carotid artery.
How does TIAs present if the ischaemic event is present in the vertebrobasilar territory?
If the ophthalmic cortex is involved there will be a homonymous hemianopia that may present purely as ignoring one side of the visual field.
There may be bilateral visual impairment. There may be hemiparesis, hemisensory symptoms, diplopia, vertigo, vomiting, dysarthria, dysphagia, or ataxia.
Ask both the patient and, if possible, those around, about weakness such as a drooping face, gait, confusion, dysarthria, loss of memory, or abnormal behaviour. Fleeting symptoms may be more obvious to those around than to the patient.
Ask about duration, intensity and fluctuation of symptoms. Establish whether there were any simultaneous cardiac symptoms.
NB: global symptoms by themselves (unsteadiness, dizziness, syncope) are rarely due to TIA.
What should you ask in the hx of a patient presenting with a TIA?
In addition to enquiring about the nature of the event, there are a number of other matters in the patient’s history that require examination:
- Has this happened before?
- Has there been recent surgery, especially on the heart or carotids?
- Has there been a previous stroke or any coronary heart disease?
- Is hypertension being treated?
- Is there known diabetes?
- Are there any other significant illnesses? There may be a hypercoagulable state or vasculitis such as temporal arteritis.
- If it presents in a person much younger than 60 years, has there been drug abuse, especially cocaine?
Which examinations are performed in a patient presenting with a TIA?
Neurological examination should be performed as for a stroke but, by the time the patient is seen, it may have reverted to normal.
Note overall attentiveness, ability to cooperate and verbal fluency
Examination of the pulse may reveal abnormality of rate or rhythm. The artery may feel hard and rigid.
Check blood pressure (BP) in both arms.Listen for a carotid bruit at the bifurcation and at the base of the neck for a vertebral bruit. However, a bruit can occur with minimal stenosis, and significant occlusion may be silent.
Check peripheral pulses.
Which investigations are performed in primary care for TIAs?
Check urine for glucose. FBC, ESR. U&E, fasting lipids and glucose. LFTs and TSH. ECG may show atrial fibrillation, myocardial infarction or evidence of myocardial ischaemia.
Which investigations are performed in secondary care for TIAs?
Patients with suspected TIA should be assessed by a specialist physician before a decision on brain imaging is made, except when haemorrhage requires exclusion in patients taking an anticoagulant or with a bleeding disorder when unenhanced CT should be performed urgently.
For patients with suspected TIA in whom brain imaging cannot be undertaken within seven days of symptoms, T2-weighted MRI imaging should be the preferred means of excluding haemorrhage.
Everyone with TIA who after specialist assessment is considered as a candidate for carotid endarterectomy should have urgent carotid imaging. If they have symptomatic carotid artery stenosis of 50-99%, people should:
- Be assessed and referred urgently for carotid endarterectomy.
- Receive optimal secondary prevention drug and lifestyle treatment.
Where there is suggestion of problems with the heart (including atrial fibrillation), echocardiogram may show atrial thrombus, aneurysm of the anterior wall of the left ventricle with mural thrombus, atrial myxoma or left-side valve disease.
Cardiac monitoring may show paroxysmal atrial fibrillation.
CT or MRI scan of the brain may show an area of reduced blood flow or an unsuspected infarct. MRI scanning tends to be more sensitive and to give better images of carotid and vertebral arteries. It may also demonstrate the rare cerebral autosomal dominant arteriopathy with subcortical infarcts and leukoencephalopathy (CADASIL).
What are the differentials for TIAs?
Todd’s paralysis
Todd’s paresis
Syncope due to cardiac arrhythmia.
Giant cell arteritis (temporal arteritis) has a very high ESR; there is often thickening and tenderness of the temporal artery, and monocular, temporary visual impairment is a frequent presentation.
Migraine, or migrainous aura.
Retinal or vitreous haemorrhage.
Focal epileptic seizure.
Labyrinthine disorders.
Transient global amnesia.
Psychological disorders (including hyperventilation).
Metabolic disturbance - eg, hypoglycaemia.
Features that do not fully fit for TIA are called transient neurological attacks (TNAs). The risk of subsequent stroke is not as high as for TIA.
Can people who had TIAs drive?
Group 1 (car or motorcycle)
- Must not drive for one month.
- No need to notify DVLA after a single TIA.
- Multiple TIAs over a short period: require three months free from further attacks before resuming driving, and DVLA should be notified.
Group 2 (lorry or bus) Licence refused or revoked for one year following a stroke or TIA.
