Brain Trauma Stroke Transient Ischaemic Attack – Obtaining a Differential Diagnosis and Predicting Patient Risk Matthew F Giles Consultant Physician, and Geriatrician, John Radcliffe Hospital, and Senior Research Fellow, Stroke Prevention Research Unit, NIHR Biomedical Research Centre, Oxford University
Abstract
Transient ischaemic attack (TIA) is common and the total number of TIAs is likely to increase with the ageing of the population. It is a heterogeneous condition with a range of possible presentations, making diagnosis challenging. The differential diagnosis includes other serious conditions, so accurate, early diagnosis is important. The risk of stroke early after TIA has recently been shown to be approximately 5% at seven days and 10–15% at three months, while overall cardiovascular risk is increased in the longer term. The ABCD2 score is a prediction tool that can be rapidly applied at the time of presentation and reliably predicts early risk of stroke. The vascular territory, aetiology of TIA and findings on cerebral imaging can also be used to predict early risk of stroke, but the degree of interaction between all these factors is uncertain.
Keywords Transient ischaemic attack, stroke, diagnosis, prognosis, risk, prediction, ABCD score
Disclosure: The author has no conflicts of interest to declare. Received: 15 April 2010 Accepted: 7 June 2010 Citation: European Neurological Review, 2010;5(1):44–8 Correspondence: Matthew F Giles, Stroke Prevention Research Unit, NIHR Biomedical Research Centre, Oxford University Department of Clinical Neurology, Level 6, West Wing, John Radcliffe Hospital, Oxford, OX3 9DU, UK. E:
matthew.giles@
clneuro.ox.ac.uk
Transient ischaemic attack (TIA) is common, with approximately 200,000–500,000 reported to medical attention in the US each year.1 The risk of TIA rises steeply with age, with the majority of all events occurring in people over 70 years of age.2
In contrast to major stroke,
Doctors from a wide range of specialities (primary care, neurology, emergency medicine, geriatrics, ophthalmology) are likely to encounter patients with suspected TIA, among whom some will have confirmed TIA with a high risk of stroke or serious non-cerebrovascular pathology; obtaining an accurate differential diagnosis and estimating risk for individual patients is therefore important for many clinicians.
the incidence of TIA is not declining and an increase in overall rates is expected over the next two to four decades as a result of the ageing of the population.3
Over the last decade there have been considerable advances in the understanding of the pathophysiology, prognosis and treatment of TIA and stroke, leading to changes in the proposed definitions and approach to management. This article will discuss the definition of TIA and stroke, how to formulate a differential diagnosis in a patient with suspected TIA and how to predict risk in individuals with a confirmed TIA.
Definitions of Transient Ischaemic Attack and Stroke
Obtaining a differential diagnosis in a condition depends on its definition, and in the case of TIA this has been hotly debated in recent years. The previous distinction between TIA and stroke was established over 30 years ago,4,5
and used time-based criteria. TIA was
defined as “an acute loss of focal brain or monocular function with symptoms lasting less than 24 hours, of presumed vascular cause”, while a stroke caused symptoms that lasted longer than 24 hours (or led to death). A new classification has been proposed that
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distinguishes between TIA and stroke on the basis of the presence or absence of brain infarction on imaging, regardless of symptom duration.6
It is argued that this ‘tissue-based’ distinction is more consistent with current knowledge of pathophysiology and prognosis.
One of the strengths of the old, time-based definition was that it carried a clear differential diagnosis that was clinically helpful when evaluating a patient with suspected TIA, presenting with transient and focal neurological symptoms. For the purposes of this article, I will therefore discuss the differential diagnosis in relation to the old time-based definition, without reference to imaging findings.
Differential Diagnosis
TIA is one of several causes of ‘transient focal neurological attacks’ (alternative causes are often termed ‘mimics’). There is no test to confirm a TIA and the gold standard method of diagnosis remains a thorough clinical assessment as soon as possible after the event by an experienced stroke physician. The advent of new imaging techniques, particularly diffusion-weighted (DWI) magnetic resonance imaging (MRI), has allowed the diagnosis to be made or excluded with more certainty in some patients.
Several tools have been developed to aid diagnosis in different clinical settings, but these have focused more on stroke than on TIA. The Recognition Of Stroke In the Emergency Room (ROSIER)7
tool was
developed for use by paramedic and emergency department (ED) staff for the rapid distinction between stroke and mimics prior to referral for specialist assessment. A further, more complex scoring system8
has
been developed for use at the bedside, again to distinguish between stroke and its mimics, in the hands of non-specialists.
© TOUCH BRIEFINGS 2010
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