Transient ischemic attack

Transient ischemic attack (TIA) is a temporary, focal cerebral ischemic event that results in reversible neurological symptoms but is not associated with a visible acute infarct on neuroimaging. Cardiogenic embolism (e.g., from atrial fibrillation) and atherosclerosis (e.g., carotid artery stenosis) are the most commonly identified etiologies. Symptoms depend on the affected territory and may mimic an acute stroke; however, symptoms are transient. Because patients with TIA have an increased stroke risk, early diagnosis and initiation of secondary preventive therapies for subsequent stroke are vital. Management typically includes urgent neuroimaging, antithrombotic therapy (e.g., antiplatelet therapy), and prompt determination of the underlying cause (e.g., using echocardiography and neurovascular studies) to guide targeted preventative measures, such as the management of underlying atrial fibrillation or carotid artery stenosis. See also ischemic stroke and overview of stroke.

TIA refers to temporary, focal cerebral ischemia that results in reversible neurologic deficits without acute infarction (i.e., imaging findings show no signs of infarction). ^[1]

• Prevalence: ∼ 2.3% ^[2][3][4]
• Incidence ^[3]
  • Increases with age
  • ♂ > ♀
• Risk factors: same as those for acute ischemic stroke (see “Risk factors” in ischemic stroke)

• See “Etiology” in ischemic stroke.
• Classification ^[5]
  • Embolic (e.g., due to atrial fibrillation)
  • Lacunar/small vessel disease (e.g., due to chronic hypertension)
  • Large vessel disease/low-flow state (e.g., atherosclerosis of MCA, severe carotid artery stenosis)
  • Blood disorders/hypercoagulable states

See differential diagnoses of stroke.

The differential diagnoses listed here are not exhaustive.

• Acute, transient focal neurologic symptoms
• Typically, symptoms last < 1 hour (the majority of cases resolve in < 15 minutes).
• Possibly amaurosis fugax
• Symptoms depend on the affected territory (see stroke symptoms by affected vessels and stroke symptoms by affected region) and etiology. ^[6]
  • Embolic: often a single, discrete episode lasting hours rather than minutes
  • Lacunar/small vessel disease: Symptoms usually resemble those seen in lacunar stroke.
  • Large vessel disease/low-flow state: often recurrent episodes lasting minutes
• Atypical symptoms may be seen. ^[7]

Approach

• Perform an initial clinical evaluation , immediate ECG, and point-of-care glucose.
• Complete laboratory studies and neuroimaging (within 24 hours of symptom onset). ^[8][9]
• Stratify the risk of subsequent stroke (see “Risk stratification” section).
• Identify and treat the underlying etiology.
• Initiate stroke prevention measures (e.g., antiplatelet agents).
• Neurology consultation is recommended for:
  • Patients with complex or high-risk TIAs requiring admission
  • All patients in follow-up to help tailor long-term stroke prevention

If there is evidence of an acute infarct on imaging, start immediate management for an acute ischemic stroke.

General principles

• TIA is a clinical diagnosis (see “Clinical features” section).
• The diagnostic evaluation for suspected TIA is similar to that for acute ischemic stroke (see “Diagnosis of ischemic stroke”).
• Ruling out alternate diagnoses and early determination of etiology are key parts of the evaluation.
• Start the workup as soon as possible following symptom onset and within 24 hours of patient presentation. ^[8][10]

Laboratory studies ^[8][10]

• Immediate: serum glucose
• Subsequent (within 24 hours of presentation)
  • CBC
  • BMP
  • Coagulation panel
  • Serum troponin
  • Serum lipid panel ^[10]
• Optional
  • Hypercoagulable workup: Consider after initial diagnostic findings, notably in younger patients with TIA and no vascular risk factors or identifiable cause. ^[1][8]
  • Toxicological screen (e.g., urine drug screen, blood alcohol level): Consider if there is clinical suspicion for drug intoxication (e.g., physical signs, history of substance misuse). ^[11][12]

Neuroimaging ^[8][10]

Neuroimaging is indicated for all patients with suspected TIA within 24 hours of presentation to rule out acute cerebral infarct (i.e., ischemic stroke).

Head CT (without IV contrast)

• Indications
  • Signs or symptoms consistent with an intracerebral hemorrhage or an acute ischemic stroke
  • If a brain MRI is unavailable
• Supportive findings: typically normal or no acute findings

MRI brain

• Indication: DW-MRI is the recommended imaging modality for a suspected TIA. ^[8]
• Supportive findings
  • Signs of reversible brain ischemia
  • Old infarcts
  • Normal study

A brain MRI is preferred for TIA evaluation, but a head CT (without IV contrast) must be performed first and immediately if there is concern for hemorrhage or acute infarction requiring reperfusion therapy.

Neurovascular studies in TIA ^[8][10]

• Indication: all patients with a suspected TIA to determine the etiology and guide secondary prevention measures
• Timing: ideally within 24 hours
• Imaging: Modality is chosen based on patient factors and institutional preferences. ^[8]
  • CTA head and neck
  • MRA head and neck
  • Transcranial doppler/carotid duplex ultrasound (TCD/CUS) ^[13]
• Supportive findings
  • Carotid artery stenosis
  • Intra- or extracranial stenotic atherosclerotic lesion
  • Intracranial embolic lesion
  • Arterial dissection

Cardiac evaluation ^[8][10]

• All patients: ECG to evaluate for atrial fibrillation or acute myocardial infarction.
• Patients with suspected embolic source or unknown etiology: Further cardiac evaluation is indicated. ^[14]
  • Echocardiography
    • TTE is preferred.
    • Consider TEE if identification of a PFO , valvular disease, or aortic arch atherosclerosis will change management. ^[8]
    • Supportive findings
      • Left atrial or ventricular thrombus
      • Dilated or restrictive cardiomyopathy
      • Patent foramen ovale (PFO)
      • Cardiac tumor
  • Cardiac monitoring: for a minimum of 24 hours to detect occult atrial fibrillation ^[1]

General considerations

• Estimating the patient's risk of a future stroke after a TIA helps guide management decisions (e.g., further diagnostic workup, treatment, and disposition).
• Individual risk depends on a combination of clinical and diagnostic parameters.
• Risk score reliability remains limited and a complete clinical risk assessment is recommended.

Clinical scoring systems

The ABCD² risk assessment score is most frequently used to assess short-term stroke risk. ^{[15][16][17][18]}

High-risk imaging findings

• Findings of high early stroke risk require rapid assessment and early secondary prevention measures.
• High risk imaging findings include:
  • Distal vertebral and proximal basilar artery lesion ^[13]
  • Distal basilar artery and middle cerebral artery lesion
  • Severe carotid artery stenosis ^[1]
  • Cerebral or cervical arterial dissection (see dissection of the carotid and the vertebral artery) ^[20]

Disposition ^[8][17]

Hospitalization should be considered for patients with suspected TIA within 72 hours of onset PLUS any of the following:

• ABCD² score: ≥ 3
• ABCD² score: 0 to 2 PLUS inability to complete outpatient workup within 2 days
• ABCD² score: 0 to 2 PLUS other evidence that the event was caused by focal ischemia
• High early stroke risk or need for intervention according to clinician judgment

General principles

• There is no specific treatment for the TIA itself.
• Therapeutic goals consist of preventing subsequent stroke (i.e., secondary prevention) and treatment of underlying conditions.
• For primary prevention measures that decrease the likelihood of a first TIA, see “Prevention” in ischemic stroke.

Antithrombotic therapy for TIA ^[1][10][21]

• Choice of agent should take the following into consideration:
  • Preventative pharmacotherapy the patient was taking at the time of the TIA event
  • TIA severity (and risk of subsequent ischemic stroke)
  • Suspected etiology
  • Patient comorbidities
• Timing: within 24 hours (start as soon as safely possible after establishing ischemic diagnosis and ruling out hemorrhage) ^[22]

Avoid triple therapy (DAPT plus anticoagulation) because of the increased risk of hemorrhage. ^[1]

Long-term stroke prevention based on suspected etiology ^[1][10]

Therapy should be tailored to the suspected underlying etiology.

• Embolic: e.g., anticoagulation for atrial fibrillation or valvular heart disease
• Lacunar/small vessel disease
  • Antiplatelet therapy
  • Treatment of hypertension (general goal < 140/90 mm Hg) ^[1]
  • Statin therapy
• Large vessel disease/low-flow state
  • Treatment of carotid artery stenosis (e.g., revascularization), if present (see “Treatment” in carotid artery stenosis)
  • Treatment of ASCVD risk factors (e.g., statin therapy, anti-hypertensive therapy)
• Blood disorders/hypercoagulable states: e.g., antithrombotic therapy for inherited/acquired thrombophilias

Management of other modifiable risk factors ^[1]

See “ASCVD prevention” for detailed information.

• Diabetes screening and treatment
• Obesity screening and lifestyle counseling
• Physical activity counseling
• Consider nutritionist consultation or assessment. ^[24]
• Consider obstructive sleep apnea (OSA) screening. ^[10]
• Smoking cessation and elimination/reduction of alcohol intake

• Determine the time of symptom onset and resolution.
• Establish IV access.
• Perform immediate ECG and POC glucose.
• Order initial laboratory studies.
• Perform immediate neuroimaging to rule out acute infarct and alternate diagnoses.
• Stratify the risk of stroke and determine appropriate disposition.
  • Low risk: Schedule appropriate outpatient studies prior to discharge.
  • High risk: Admit to hospital under internal medicine or neurology service.
• Consider immediate antiplatelet therapy (see antithrombotic therapy for TIA).
• Complete appropriate neurovascular studies within 24 hours of admission.
• Consider further cardiology studies.
• Initiate secondary prevention measures according to the underlying etiology.
• Address modifiable risk factors.

A brain MRI is preferred for TIA evaluation but a head CT (without IV contrast) must be performed first and immediately if there is concern for hemorrhage or acute infarction requiring reperfusion therapy.

If there is evidence of an acute infarct on imaging, start immediate management for an acute ischemic stroke.

• Increased risk of future ischemic stroke ^[3]
  • Within 2 days: ∼ 3–10%
  • Within 90 days: ∼ 9–17%