Practice Essentials
In 2009, the American Heart Association and the American Stroke Association (AHA/ASA) published a scientific statement that revised the definition of transient ischemic attack (TIA) to the following: “a transient episode of neurologic dysfunction caused by focal brain, spinal cord or retinal ischemia without acute infarction.”
Prior to this revised definition, TIA was often operationally defined based on symptom duration lasting less than 24 hours, with typical episodes lasting less than 1 hour. The de-emphasis on duration was due to multiple studies demonstrating that up to 50% of classically defined TIAs showed brain injury on magnetic resonance imaging (MRI).
On average, the annual risk of future ischemic stroke after a TIA or initial ischemic stroke is 3–4%,
with an incidence as high as 11% over the next 7 days and 24–29% over the following 5 years.
Signs and symptoms
A TIA may last only minutes, and symptoms often resolve before the patient presents to a clinician. Thus, historical questions should be addressed not just to the patient but also to family members, witnesses, and emergency medical services (EMS) personnel regarding changes in any of the following:
Behavior
Speech
Gait
Memory
Movement
Initial vital signs should include the following:
Temperature
Blood pressure
Heart rate and rhythm
Respiratory rate and pattern
Oxygen saturation
The examiner should assess the patient’s overall health and appearance, making an assessment of the following:
Attentiveness
Ability to interact with the examiner
Language and memory skills
Overall hydration status
Development
The goals of the physical examination are to uncover any neurologic deficits, to evaluate for underlying cardiovascular risk factors, and to seek any potential thrombotic or embolic source of the event. Ideally, any neurologic deficits should be recorded with the aid of a formal and reproducible stroke scale, such as the National Institutes of Health Stroke Scale (NIHSS).
A neurologic examination is the foundation of the TIA evaluation and should focus in particular on the neurovascular distribution suggested by the patient’s symptoms. Subsets of the neurologic examination include the following:
Cranial nerve testing
Determination of somatic motor strength
Somatic sensory testing
Speech and language testing
Assessment of the cerebellar system (be sure to watch the patient walk)
See Presentation for more detail.
Diagnosis
It is important to rule out other causes, such as metabolic or drug-induced etiologies, which can present with symptoms similar to that of TIA. The following tests are considered on an emergency basis:
A fingerstick blood glucose for hypoglycemia
Complete blood count
Serum electrolyte levels
Coagulation studies
12-lead electrocardiogram (ECG) with rhythm strip
The following tests typically are helpful and often can be performed on an urgent basis:
Erythrocyte sedimentation rate
Cardiac enzymes
Lipid profile
Additional laboratory tests, ordered as needed and on the basis of the history, include the following:
Screening for hypercoagulable states (particularly in younger patients with no known vascular risk factors)
Syphilis serology
Antiphospholipid antibodies
Toxicology screens
Hemoglobin electrophoresis
Serum protein electrophoresis
Cerebrospinal fluid examination
Imaging of the brain should be performed within 24 hours of symptom onset, as follows
:
Magnetic resonance imaging (MRI) with diffusion-weighted imaging (preferred)
Noncontrast computed tomography (CT; ordered if MRI is not available)
The cerebral vasculature should be imaged urgently, preferably at the same time as the brain. Vascular imaging for TIA includes the following:
Carotid Doppler ultrasonography of the neck
CT angiography (CTA)
Magnetic resonance angiography (MRA)
See Workup for more detail.
Management
The following should be done urgently in patients with TIA
:
Evaluation
Risk stratification (eg, with the California or ABCD score
)
Initiation of stroke prevention therapy
For patients with a recent (≤1 week) TIA, guidelines recommend a timely hospital referral with hospitalization for the following:
Crescendo TIAs
Duration of symptoms longer than 1 hour
Symptomatic internal carotid stenosis greater than 50%
Known cardiac source of embolus (eg, atrial fibrillation)
Known hypercoagulable state
Appropriate combination of the California score or ABCD score (category 4)
In view of the high short-term risk of stroke after TIA, antithrombotic therapy should be initiated as soon as intracranial hemorrhage has been ruled out. For noncardioembolic TIA, the following antiplatelet agents are all reasonable first-line options for initial therapy:
Aspirin (50-325 mg/day)
Aspirin plus extended-release dipyridamole
Clopidogrel
Stroke prevention medication typically recommended for cardioembolic TIA is as follows:
For patients with atrial fibrillation after TIA, long-term anticoagulation with warfarin (target international normalized ratio [INR], 2-3); aspirin 325 mg/day for those unable to take oral anticoagulants
In acute myocardial infarction (MI) with left ventricular thrombus, oral anticoagulation with warfarin (target INR, 2-3; concurrent aspirin up to 162 mg/day for ischemic coronary artery disease [CAD])
In dilated cardiomyopathy, oral anticoagulation with warfarin (target INR, 2-3) or antiplatelet therapy
In rheumatic mitral valve disease, oral anticoagulation with warfarin (target INR, 2-3)
For patients with TIA due to 50-99% stenosis of a major intracranial artery, the following is recommended:
Aspirin 50-325 mg/day rather than warfarin
Maintenance of blood pressure below 140/90 mm Hg and total cholesterol below 200 mg/dL
Angioplasty or stent placement is investigational and of unknown utility
See Treatment and Medication for more detail.