Tests
1st tests to order
blood glucose
Test
Hypoglycemic events can elicit global symptoms such as confusion or syncope, but can also lead to focal symptoms.
Hypoglycemia needs to be ruled out as a mimic of TIA.
Every patient with TIA should be screened for diabetes mellitus by measuring fasting plasma glucose or hemoglobin A1c, or with an oral glucose tolerance test.[13][21]
Point-of-care capillary blood glucose provides rapid information, but venous blood glucose is more accurate.
Result
blood glucose <60 mg/dL suggests hypoglycemia as mimic of TIA
chemistry profile
Test
Severe hyponatremia can trigger seizures or induce generalized weakness.
Extremely low potassium or very high calcium can also cause generalized weakness.
These abnormalities are usually suggested by other elements of the history.
Result
usually normal; very low sodium, low potassium, or high calcium suggests nonischemic cause of symptoms
CBC
Test
Elevated WBC can suggest infection as cause of symptoms.
Profound anemia can cause weakness, but usually this would be generalized.
Polycythemia, extreme thrombocytosis, or extremely high WBC count can contribute to risk of poor cerebral perfusion.
Thrombocytopenia is a risk factor for intracerebral hemorrhage and a contraindication to tissue plasminogen activator (tPA) therapy in cases in which a second stroke occurs.
Result
usually normal
prothrombin time, INR, and activated PTT
Test
This is used if the neurologic deficit persists at time of presentation, there is reason to suspect abnormal coagulation (such as liver disease or use of anticoagulant therapy), and thrombolytic therapy for stroke is being considered.[21] Completing these tests in high-risk patients for early second ischemic events could speed future thrombolysis decisions.
Result
normal unless the patient is already on anticoagulation, or has liver disease or antiphospholipid antibodies
ECG
Test
Should be performed in all patients presenting with acute neurologic deficit to evaluate for atrial fibrillation and other arrhythmias.[21]
Atrial fibrillation increases the risk for embolic cerebral ischemia.
Other abnormalities such as bundle branch blocks or ventricular hypertrophy are more nonspecific findings of underlying cardiac disease that may reflect congestive heart failure or common risk factors for atherosclerotic disease.
Result
atrial fibrillation may be present
brain MRI with diffusion
Test
If positive, MRI can localize infarct, suggest etiology, and distinguish TIA from stroke.[2][13] The presence of infarction confirms ischemia and abnormal diffusion-weighted images increases risk of future events.
Abnormal diffusion images are reversible in some but not all patients who have resolution of clinical deficits.
MRI can also evaluate for alternative etiologies such as plaques of multiple sclerosis or mass lesions.
If diffusion-weighted imaging is negative and there is a strong clinical suspicion of TIA, perfusion-weighted imaging may be performed during the same MRI examination; in 30% of cases, a focal perfusion deficit is identified in the brain area corresponding to the symptoms.[3][64][65]
Result
half will have positive diffusion images
fasting lipid profile
Result
guidelines recommend treatment with statin therapy for all patients with TIA barring contraindication; patients do not require documentation of elevated lipid level to initiate treatment, and guidelines do not recommend the treat-to-target strategy
Tests to consider
head CT
Test
Typically patients undergo a noncontrast head CT, to exclude a brain hemorrhage and guide treatment with thrombolysis.[2][44]
Head CT scan has poor ability to rule out ischemia in TIA or early stroke.[13][60] However, CT has nearly 100% sensitivity in ruling out acute hemorrhage.
Patients with resolved symptoms may not require a CT scan, and may receive an MRI of the brain, if available.
Result
usually normal
erythrocyte sedimentation rate (ESR)
Test
ESR is recommended as part of the workup for central nervous system vasculitis such as temporal arteritis but is not routine in many centers.
Temporal artery tenderness, jaw claudication, or symptoms of polymyalgia rheumatica in an older patient would be an appropriate trigger for ordering this test.
Result
most useful if vasculitis is suspected; generally not markedly elevated unless systemic illness or vasculitis is present
telemetry/Holter monitor
Test
Should be performed in all patients with a TIA to evaluate for atrial fibrillation and other arrhythmias.[21]
Presence of even intermittent atrial fibrillation increases the risk of embolic events. Extended Holter monitoring will identify new atrial fibrillation/flutter in more patients than ECG and short-term telemetry monitoring.[21][66][67]
Result
intermittent atrial fibrillation; cardiac monitoring for 30 days detects paroxysmal atrial fibrillation in 7% of patients that would not have been diagnosed using short-duration ECG monitoring, and often results in change to anticoagulation for secondary prevention
echocardiogram ± bubble study
Test
Transthoracic echocardiography (TTE) is preferred over transesophageal echocardiography (TEE) for the detection of left ventricular thrombus, but TEE is superior to TTE in detecting left atrial thrombus, aortic atheroma, prosthetic valve abnormalities, native valve abnormalities, atrial septal abnormalities, and cardiac tumors.[21] Bubble studies can establish if there are intracardiac shunts for selected patients such as those with TIA under the age of 65 years without risk factors, and patients with cryptogenic TIA or neurologic deficits occurring with Valsalva.[47] Transcranial Doppler with bubble study may help quantify the magnitude of a right-to-left shunt and can be performed simultaneously with a TTE bubble study.
Result
variable; most likely to change management in patients with history of cardiac disease, abnormal cardiac exam, or abnormal ECG
carotid Doppler ultrasound
Test
Ultrasound is a screening test for stenosis.
Presence of ipsilateral carotid stenosis suggests artery-to-artery embolic event as etiology and is a target for surgical or interventional treatment.
CT angiography or magnetic resonance angiography may be used as follow-up tests to expand on abnormal carotid Doppler ultrasound results.[2]
Carotid Doppler is not useful in posterior circulation TIAs. Intracranial vasculature is not visualized with carotid Doppler.[2]
Result
presence of stenosis
CT angiography
Test
Recommended in patients with symptomatic anterior circulation cerebral infarction or TIA who are candidates for revascularization.[2][21] High-resolution imaging of the intracranial large arteries and imaging of the extracranial vertebrobasilar arterial system can also be used to identify atherosclerotic disease, dissection, moyamoya disease, or other etiologically relevant vasculopathies.[21]
Result
presence of stenosis, dissection, moyamoya
magnetic resonance angiography (MRA)
Test
Recommended in patients with symptomatic anterior circulation cerebral infarction or TIA who are candidates for revascularization.[2][21] Owing to the relatively rapid and noninvasive nature of the exam obviating the need for intravenous contrast, MRA may be preferable to CT angiography in patients with renal impairment, x-ray contrast allergy, or repeat presentations.[2] However, noncontrast MRA of the neck tends to overestimate the degree of carotid stenosis when compared with contrast-enhanced MRA, particularly in cases of high-grade stenosis.[2][48] High-resolution imaging of the intracranial large arteries and imaging of the extracranial vertebrobasilar arterial system can also be effective in identifying atherosclerotic disease, dissection, moyamoya, or other etiologically relevant vasculopathies.[21]
Result
presence of stenosis, atherosclerosis, dissection, moyamoya
transcranial Doppler
Test
Not commonly performed. In patients with ischemic stroke or TIA in whom patent foramen ovale (PFO) closure is contemplated, transcranial Doppler with embolus detection might be reasonable to screen for, and detect the magnitude of, right-to-left shunt.[21] Transcranial Doppler compares favorably with transthoracic echocardiography (TTE) for detecting right-to-left shunting, which is usually the result of PFO.[21] In rare cases this may be done as a complementary test to further evaluate intracranial stenosis suggested in the absence of CT/MRI.[2][49]
Result
presence of intracranial circulation stenosis
hypercoagulability studies
Test
Ordered in unexplained TIA in a young patient with self-history or family history of unprovoked thrombosis, prior miscarriages, or coexistence of systemic signs and symptoms suggestive of hypercoagulability.[21]
The thrombophilic states most associated with arterial thrombus are antiphospholipid antibodies or hyperhomocysteinemia.
Result
usually negative unless significant family history or unexplained TIA in a young patient
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