How not to miss: TIA
Dr Paul Holmes explains how to differentiate TIA from conditions with similar presentations
Worst outcomes if missed
•Stroke and significant disability
associated with TIA.
•The risk of developing a stroke after a hemispheric TIA can be as high as 30 per cent within the first month, with the
greatest risk being within the first 72 hours.
Epidemiology and Incidence
While there have been a number of studies worldwide of the epidemiology of transient ischaemic attack, the most robust study in the UK is the Oxfordshire Community Stroke Project, carried out between 1981 and 1986. The annual incidence rate per 1,000 population was 0.92 for people aged 55-64, 1.61 for those aged 65-74, 2.57 for those aged 75-84, and 2.32 for people 85 and over.
The overall incidence is similar in males and females, though the incidence in 55- to 84-year-olds is higher in men than in women. Oxfordshire has one of the lowest death rates from stroke in the UK, and so it is likely that TIA incidence is higher elsewhere in the country. Approximately 80 per cent of the TIAs were in the carotid distribution, and 20 per cent in the vertebro-basilar distribution, which is similar to findings elsewhere.
The overall prevalence of stroke is estimated to be 47 per 10,000 and as such is the most common cause of adult physical disability.
Risk factors that play a role in TIA are hypertension, smoking, high cholesterol and diabetes. Being overweight, leading a sedentary lifestyle, excessive alcohol intake and having a poor diet all contribute to cardiovascular risk.
Symptoms and signs
A TIA is characterised by an acute loss of focal cerebral or monocular function with symptoms lasting less than 24 hours. It is due to inadequate cerebral/ocular blood supply as a result of arterial thrombosis or embolism (artery, cardiac, haematological disease). It is a clinical diagnosis without specific diagnostic test and the doctor relies on a constellation of clinical features to make the diagnosis (see diagram below). Symptoms include:
•Sudden loss of motor function in an arm or leg
•Sudden onset of a hemisensory
•Sudden diplopia with vertigo
•Facial sensory disturbance and
•Sudden loss of vision in an eye where
vision fades to grey/black
The box (below left) gives some major pitfalls in diagnosing TIA.
Other conditions may present with focal neurological disturbance and need to be differentiated from TIA. These include:
•Migraine aura (with/without headache)
•Partial (focal) epilepsy
•Labyrinthine disturbances such as
Meniere's disease, BPPV, benign recurrent vertigo, labyrinthitis/vestibular neuronitis
•Transient global amnesia (TGA)
•Intracranial structural lesion such as AVM, chronic subdural
•Metabolic disturbances such as hypo/
•Peripheral nerve lesion such as
•Psychological causes such as
hyperventilation attacks/panic attacks, or somatisation
What to do if you see a patient with a TIA
If the patient is likely to have had a TIA, it is important that he/she is seen and investigated urgently. GPs should refer patients to a neurovascular clinic. The Royal College of Physicians guidelines recommend that patients have the diagnosis and cause established as far as possible within seven days of the event to minimise the risk of progressing to stroke. Patients with hemispheric TIA and hypertension, for example, have a 20-30 per cent chance of developing stroke within the first month after TIA.
Unless there are reasons suggesting cerebral haemorrhage (such as sudden severe head-ache at onset), the guidelines recommend starting aspirin 300mg pending investigation. Patients with more than one TIA in a week should be investigated in hospital immediately. ECG is important in looking for atrial fibrillation.
All these are carried out in secondary care.
The North American Symptomatic Endarterectomy Trial (NASCET) and The European Carotid Surgery Trial (ECST) concluded that carotid endarterectomy was highly beneficial for patients with recent TIAs or non-disabling strokes with ipsilateral carotid stenosis of 70-90 per cent. This benefit is seen early and patients should undergo surgery as soon as possible, preferably within two weeks of symptom onset.
Carotid artery stenting
This is an option for treatment of symptomatic carotid artery stenosis and has been shown in trials to have similar success and complication rates but is still the subject of ongoing trials (ICSS). Stenting is helpful in high surgical risk patients with symptoms, recurrent stenosis, radical neck dissection or irradiation or a high carotid bifurcation.
CT or MRI
Used primarily to rule out haemorrhage or where there is doubt about the symptoms being related to cerebral ischaemia where other pathologies may be shown.
Paul Holmes is a consultant neurologist at Guy's and St Thomas' NHS foundation trust – he works closely with the stroke team
Competing interests None declared
The following non-focal neurological symptoms do not suggest TIA unless accompanied by focal neurological symptoms:
• Non-specific dizziness
• Mental disorientation
• Drop attacks