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Brain Trauma Stroke
Transient Ischaemic Attack in the Acute Setting –
Diagnosis, Management and Treatment
a report by
Archit Bhatt,
1
Ted Glynn
2
and Mathew J Reeves
3
1. Department of Neurology and Ophthalmology; 2. Department of Medicine; 3. Department of Epidemiology,
College of Human Medicine, Michigan State University
More than 700,000 acute strokes
1
and 300,000 transient ischaemic overall agreement rates varying between 39 and 67%.
18–21
In a recent
attacks (TIAs)
2,3
occur annually in the US. It is estimated that between 15 study of 100 hospitalised patients who had a presumptive ED-based
and 26% of acute stroke cases have a prior history of TIA.
4
TIAs are diagnosis of TIA, a retrospective chart review by two stroke neurologists
important because they are associated with high short-term risk of both found that 60% were misdiagnosed.
22
However, such results should not
stroke and cardiac events. In a widely quoted emergency department (ED) be interpreted as necessarily reflecting the clinical skills of neurologists and
study of over 1,700 TIA cases from California, the three-month stroke risk ED physicians; rather, these data are a reflection of the fact that more
was found to be 10.5%.
5
A recent meta-analysis of 11 TIA cohort studies complete and definitive diagnostic information (e.g. brain imaging, carotid
found that the summary estimate for the 90-day stroke risk was 9.2% – imaging) is typically not obtained until after the patient is admitted to the
very similar to the Californian study.
6
This meta-analysis also confirmed hospital.
22
Difficulties in making an accurate diagnosis of TIA in the ED
that most of this stroke risk occurs in the first few days after the TIA setting arise from several factors. First, time constraints resulting from pre-
event; the risk of stroke was 3.5% at two days and 8.0% at 30 days.
6
hospital delays
23,24
and rapid triage and assessment requirements make
Similar findings were found in another recent meta-analysis of 18 cohort the process especially difficult in a busy ED. Second, differentiating
studies, which estimated that the seven-day risk of stroke was 5.2%.
7
common stroke mimics from TIA can be difficult, particularly for non-
Patients with TIA are also at high risk of other cardiovascular events. In a stroke physicians.
25
Even differentiating TIA from ischaemic stroke can be
meta-analysis of 39 cohort studies, the annual risk of myocardial challenging when reliable information on the exact onset time of
infarction and non-stroke vascular death following TIA was 2.2 and symptoms is lacking. Third, terms such as ‘TIA’, ‘TND’ (transient
2.1%, respectively.
8
These studies, which serve to illustrate the high neurological deficits), ‘mini stroke’ and ‘minor stroke’, which may signify
risk of cardiovascular events following a TIA, suggest that patients different underlying pathology and aetiology, are often liberally applied in
suspected of having a TIA event require an expedited clinical work-up. the ED setting, and may or may not identify a patient who meets the
Historically, TIA has been defined on the basis of focal neurological formal definition of TIA (i.e. transient focal neurological symptoms of <24
deficits due to transient and reversible cerebral or retinal hypoperfusion hours’ duration). Fourth, the frequent use of terms such as ‘rule-out TIA’,
lasting for less than 24 hours.
9
However, because the duration of ‘suspect TIA’, ‘possible TIA’ or ‘TIA/stroke’ in the ED setting may reflect
symptoms for most TIAs is much less than 24 hours – typically less than either a reluctance on behalf of the ED physician to make a definitive
TIA
10
– there has been a proposed change in the definition of TIA to diagnosis based on limited clinical information, and/or the inherent
include only cases with a symptom duration of less than one hour.
11,12
difficulty in ruling out alternative diagnoses in the limited time available.
The advent of diffusion-weighted imaging (DWI) technology adds further
challenges to the traditional definition of TIA – up to 50% of TIA patients
Archit Bhatt is a board-certified internist and Chief
have DWI abnormalities indicating ischaemic changes.
13–15
The presence
Neurology Resident in the Department of Neurology at
of positive DWI changes in TIA cases has been shown to be associated
Michigan State University. He is the founding Editor of
with longer symptom duration (>60 mins), the presence of speech
Neurohospitalist Journal and an elected member of the Delta
Omega Honors Society of Public Health. Dr Bhatt carried
disturbance, atrial fibrillation and ipsilateral carotid stenosis.
13
out his residency training and fellowship in neurology at
Michigan State University.
Accuracy of Transient Ischaemic Attack
Diagnosis in the Urgent Setting
Ted Glynn is a board-certified emergency medicine physician
The diagnosis of TIA has always been a clinical challenge even for
in the Departments of Emergency Medicine at Ingham
Regional Medical Center and Sparrow Health System in
neurologists. Two carefully conducted diagnostic studies undertaken in
Lansing, Michigan. He is also Program Director for the
outpatient or non-acute settings demonstrated that the inter-rater Michigan State University Emergency Medicine Program.
agreement among neurologists for the diagnosis of TIA was actually good
(kappa = 0.65–0.77).
16,17
In one study of 56 patients, the overall
agreement for TIA diagnosis between pairs of neurologists who each
interviewed the patients was very high (85%; n=48).
16
In the other study
Mathew J Reeves is an Associate Professor in the
Department of Epidemiology, College of Human Medicine,
evaluating the validity of TIA diagnosis in 72 patients, the overall
Michigan State University. His areas of interest include
agreement between neurologists was also very high (88%; n=64).
17
translational clinical research in stroke and evidence-
However, many cases of TIA present to the ED, where an ED physician
based medicine.
rather than a neurologist evaluates them. Achieving optimal diagnostic
E:
reevesm@msu.edu
accuracy for TIA is even more challenging in the ED setting. The reported
accuracy of TIA diagnosis among non-neurologists is quite variable, with
© TOUCH BRIEFINGS 2008 47
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