Transient Ischemic Attack Workup

Updated: Sep 11, 2017
  • Author: Ashish Nanda, MD; Chief Editor: Andrew K Chang, MD, MS  more...
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Workup

Approach Considerations

Ruling out metabolic or drug-induced causes of symptoms consistent with a transient ischemic attack (TIA) is important. Initial assessment is aimed at excluding emergency conditions that can mimic a TIA (eg, hypoglycemia, seizure, or intracranial hemorrhage). A fingerstick blood glucose test should be performed and blood drawn for a complete blood count (CBC), coagulation studies, and serum electrolyte levels. Obtain a 12-lead electrocardiogram (ECG) with rhythm strip, and evaluate for symptomatic arrhythmias or evidence of ischemia.

Brain imaging is recommended within 24 hours of symptom onset. Although magnetic resonance imaging (MRI) with diffusion-weighted imaging (DWI) is preferred, noncontrast computed tomography (CT) of the head is a reasonable first choice when MRI is not readily available. [1, 8, 4]

The cerebral vasculature should be imaged on an urgent basis, preferably at the same time as the brain. Brain imaging can identify an area of ischemia in as many as 25% of patients, and TIA mimics may be identified as well. Vessel imaging can identify a stenosis or occlusion that may warrant early intervention.

Electroencephalography (EEG) may be indicated to evaluate for seizure activity. Lumbar puncture (LP) may be indicated if subarachnoid hemorrhage, central nervous system (CNS) infection, or demyelinating disease is to be excluded.

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Laboratory Studies

The following tests are considered on an emergency basis:

  • Serum chemistry profile, including creatinine
  • Screening coagulation studies
  • CBC

The following tests may be helpful and often can be performed on an urgent basis:

  • Erythrocyte sedimentation rate (ESR)
  • Cardiac enzymes
  • Lipid profile

Screening for hypercoagulable states (particularly in younger patients with no known vascular risk factors) may be performed, though this practice is not evidence-based. Tests include the following [1] :

  • Protein C, protein S, and antithrombin III activities
  • Activated protein C resistance/factor V Leiden
  • Fibrinogen
  • D-dimer
  • Anticardiolipin antibody
  • Lupus anticoagulant
  • Homocysteine
  • Prothrombin gene G20210A mutation
  • Factor VIII
  • Von Willebrand factor
  • Plasminogen activator inhibitor-1
  • Endogenous tissue plasminogen activator activity

Additional laboratory tests, ordered as needed and on the basis of the history and examination, include the following:

  • Syphilis serology
  • Antiphospholipid antibodies
  • Toxicology screens
  • Hemoglobin electrophoresis
  • Serum protein electrophoresis
  • Cerebrospinal fluid examination
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Noncontrast Cranial Computed Tomography

Noncontrast cranial CT is widely and rapidly available and often serves as the initial imaging evaluation. It can aid in diagnosing the following:

  • A new area of ischemia or infarction
  • Old areas of ischemia
  • Intracranial mass, such as tumor
  • Intracranial bleeding, such as subdural hematoma or intracerebral hemorrhage
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Magnetic Resonance Imaging

MRI is more sensitive than CT for acute ischemia, infarction, previous intracranial bleeding, and other underlying lesions; however, it is less widely available on an acute basis than CT is.

The presence of ischemic lesions on MRI appears to increase the short-term risk of stroke, a finding that highlights the value of this modality in acute risk stratification. [20, 21, 22] In addition, negative DWI in concert with low-risk clinical features can identify patients at minimal short-term stroke risk. [23] Patients with DWI abnormalities, despite low ABCD2 scores (see Risk Stratification Scores), may be at just as high a risk for stroke as patients with high ABCD2 scores but no DWI abnormalities. [24]

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Vascular Imaging Studies

Vascular imaging for TIA includes Doppler ultrasonography, CT angiography (CTA), and magnetic resonance angiography (MRA). CTA is of increasing value in identifying occlusive disease in the cerebrovascular circulation. MRA is another alternative for imaging vessels in both the brain and the neck. Conventional catheter angiography can be performed when the other modalities are unavailable or yield discordant results.

Carotid Doppler ultrasonography of the neck can be used to identify patients in need of urgent surgical or endovascular therapy. Transcranial Doppler can be a complementary examination evaluating the patency of cerebral vessels and collateral circulation.

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Cardiac Imaging and Monitoring

Transthoracic (TTE) or transesophageal echocardiography (TEE) can evaluate for a cardioembolic source or for risk factors such as patent foramen ovale. A 12-lead ECG should be performed as soon as possible after TIA to evaluate for dysrhythmias such as atrial fibrillation. Cardiac monitoring (inpatient telemetry or Holter monitoring) may be useful in patients without a clear diagnosis after initial brain imaging and ECG.

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Risk Stratification Scores

Some patients present to the emergency department (ED) with a transient neurologic disturbance that does not represent a true TIA, and distinguishing between such disturbances and TIAs can be difficult for the busy practitioner. In addition, an emergency comprehensive workup of all patients with “possible TIA” may not be the most cost-effective or appropriate use of limited local resources. Appropriate risk stratification must be employed to ensure that diagnostic and therapeutic interventions are targeted to the highest-risk patients.

A number of risk stratification scores are available to assist in this task, but the most widely validated is the ABCD2 score. [21, 25, 26] (See Table 2 below.)

Table 2. ABCD2 Score (Open Table in a new window)

A: Age ≥60 years 1 point
: Blood pressure: Systolic ≥140 mm Hg or diastolic ≥90 mm Hg 1 point
C: Clinical features  
Unilateral weakness with or without speech impairment 2 points
Speech impairment without unilateral weakness 1 point
D: Duration  
≥60 min 2 points
10-59 min 1 point
D: Diabetes 1 point
Total 0-7 points

Individuals with an ABCD2 score of 6 or 7 have an 8% risk of stroke within 2 days, whereas those with an ABCD2 score lower than 4 have a 1% risk of stroke within 2 days. [8] Some of these patients with lower scores may well have non-TIA events rather than true TIAs. [27]

It has been proposed that this scoring system can be used to risk-stratify ED patients for emergency workup and to predict the severity of recurrent stroke after TIA. [25, 28, 29, 30] Others have suggested that when a comprehensive workup can be obtained routinely in the ED, the value of the ABCD2 score diminishes significantly. [31] Some groups have noted, however, that short-term stroke risk after TIA can be worrisome even in those with low ABCD2 scores. [32, 33]

ABCD3 score

One group has developed 2 variations of the ABCD2 score that may improve risk stratification after TIA in secondary settings. The ABCD3 score assigns 2 points for dual TIA (an earlier TIA within 7 days of the index event), and the ABCD3 imaging score adds stenosis of at least 50% on carotid imaging (2 points) and abnormal DWI (2 points). However, further validation and study are needed before use of the ABCD3 score can be recommended. [34]

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