Definition and Overview
Transient ischemic attack (TIA) is a condition in which neurological deficit symptoms appear temporarily and disappear completely due to local ischemia of the brain, spinal cord, or retina. In modern definitions, it is limited to cases without tissue infarction. In the past, TIA was defined if symptoms disappeared within 24 hours, but if infarction was confirmed on MRI diffusion-weighted imaging (DWI), it was classified as cerebral infarction regardless of symptom duration.
TIA is a strong precursor to cerebral infarction. The incidence of stroke within 90 days after a TIA is approximately 10-15%, with half of this risk occurring within the first 48 hours. Therefore, TIA is a neurological emergency requiring immediate medical evaluation.
Causes and Mechanisms
Thromboembolic mechanism
The most common cause of TIA is temporary vascular occlusion by an atherosclerotic thrombus. Symptoms disappear when blood clots or emboli formed in the carotid artery, aorta, and heart temporarily block cerebral blood vessels and then naturally dissolve and blood flow is restored.
The main causes are as follows:
- Large vessel atherosclerosis: carotid artery stenosis, intracranial artery stenosis
- Cardiogenic embolism: atrial fibrillation, blood clots after myocardial infarction, heart valve disease
- Small vessel disease: Cerebral small vessel disease caused by high blood pressure and diabetes
- Other: coagulopathy, arterial dissection, vasculitis
hemodynamic mechanism
When there is a sudden drop in blood pressure, orthostatic hypotension, or decreased cardiac output, the ability to automatically regulate cerebral blood flow is reduced, resulting in ischemia.
symptoms
Symptoms of TIA vary depending on the area of ischemia, and last for several minutes to tens of minutes before fully recovering.
Anterior circulation (carotid system) symptoms
- Unilateral limb paralysis or numbness
- Speech impairment: slurred speech (dysarthria), inability to speak or understand (aphasia)
- Temporary loss of vision in one eye (transient monocular blindness, amaurosis fugax)
Posterior Circulation (Vertebral Basilar Artery System) Symptoms
- Double vision (seeing double)
- Bilateral limb weakness
- Balance disorders and gait ataxia
- severe dizziness
- dysphagia
diagnosis
ABCD2 Risk Score
The ABCD2 score is used to rapidly assess early stroke risk after TIA.
- A(Age): Age ≥ 60 years → 1 point
- B (Blood pressure): Systolic ≥ 140 or diastolic ≥ 90 mmHg → 1 point
- C (Clinical features): Hemiparesis → 2 points, dysarthria (without paralysis) → 1 point
- D (Duration): Symptoms persist ≥ 60 minutes → 2 points, 10~59 minutes → 1 point
- D (Diabetes): Diabetes → 1 point
0~3 points: low risk, 4~5 points: moderate risk, 6~7 points: high risk
imaging test
- Brain MRI (including DWI): essential to confirm the presence of infarction, more sensitive than CT
- Carotid ultrasound and MRA/CTA: assessment of carotid artery stenosis and intracranial vessels.
- Cardiac tests: electrocardiogram, echocardiogram (evaluate causes of cardiogenic emboli)
- Blood tests: CBC, coagulation tests, fasting blood sugar, lipid panel
Treatment and Prevention
first aid
As soon as a TIA occurs, visit the emergency room and undergo a brain MRI, blood vessel examination, and heart examination. The EXPRESS study found that immediate access to a specialized TIA treatment clinic reduced stroke rates by approximately 80% within 90 days.
antithrombotic treatment
- Antiplatelet agents: In non-cardiogenic TIA, aspirin ± clopidogrel dual antiplatelet therapy is administered for a short period of time.
- Anticoagulants: If psychogenic causes such as atrial fibrillation are confirmed, NOAC or warfarin treatment is started.
Risk factor management
- Hypertension: Target systolic blood pressure below 130 mmHg
- Hyperlipidemia: Statin treatment, goal of LDL cholesterol less than 70 mg/dL
- Diabetes: Blood sugar control (HbA1c < 7%)
- Carotid artery stenosis: If stenosis is ≥ 70%, consider carotid endarterectomy or stent implantation.