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