creation date: 2026-02-19 16:37
tags: Pathologies
Transient Ischemic Attack
Background
Definitions
Transient ischemic attacks (TIA) refers to a transient episode of neurologic dysfunction caused by focal brain or retinal ischemia without evidence of acute infarction. They are sometimes referred to as “mini-strokes”.
This definition is the currently used tissue-based definition. Historically, a time-based definition was used, defining TIA as a sudden onset focal neurological deficit lasting less than 24 hours.
Etiology and Pathophysiology
There are three main mechanism that results in a TIA.
Embolic TIA
TIA may result from artery-to-artery emboli, a proximal source (eg. cardiac or aortic), or be cryptogenic.
Embolism results in a discrete occlusion which is characterized by a single, more prolonged episode of focal neurologic symptoms. Although typically discrete, recurrent emboli may result in variable symptoms.
Natural thrombolysis occurs as the emboli originate from fresh thrombus, recanalizing the vessel.
Lacunar or small penetrating vessel TIA
Lacunar or small vessel TIA occur due to transient ischemia caused by stenosis of the vessel. The typically affected vessels are the intracerebral penetrating vessels arising from the MCA stem, basilar artery, vertebral artery, or the circle of Willis.
Stenosis is caused by either atherothrombotic obstructive lesions at the origin of the penetrating vessels or by lipohyalinosis distally.
Large artery, low-flow, or hemodynamic TIA
These TIAs are associated with a tightly stenotic atherosclerotic lesion at the internal carotid artery (ICA) origin or in the intracranial portion of the ICA.
Symptoms largely depend on the sites of impaired:
- Anterior circulation: weakness/numbness of hand, arm, leg, face, tongue, and/or cheek
- Posterior circulation: vertigo/dizziness, unilateral numbness
- Rarely: repetitive jerking movement of the arm or leg
Clinical Presentation
Signs & Symptoms
Typical TIA is characterized by transient, focal neurologic symptoms, with sudden onset. It may include one or more of the following:
- Transient monocular blindness
- Aphasia or dysarthria
- Hemianopia (loss of half of visual field)
- Hemiparesis and/or hemisensory loss
Atypical TIA may present with the following characteristics:
- Gradual buildup of symptoms (over >5 mins)
- March of symptom from one body part to another without passing midline
- Progression of symptom from one type to another
- Isolated (positive phenomena) disturbances of vision in both eyes
- Isolated sensory symptoms with markedly focal distribution
- Very brief spells (<30 seconds)
- Identical spells reoccuring
- Isolated brainstem symptoms (dysarthria, diplopia, hearing loss)
- Amnesia, confusion
- Incoordination of limbs
History & Physical Exam
A detailed history of the occurrence including:
- Symptoms present
- Duration and onset of symptoms
Risk stratification can be done using the ACBD2 score. However, studies have found its efficacy uncertain.
A physical exam with neurologic exam may or may not appreciate focal deficits depending on time since onset. Cardiovascular exam should be performed for possible emboli source (eg. rhythm and murmurs)
Risk Factors
Diagnosis
Criteria
Diagnosis of TIA is based on the clinical features of the attack and neuroimaging findings.
It should be noted that patients rarely present when fully symptomatic so diagnosis is made based on history from the patient and bystanders.
Work-up
Brain imaging
Imaging with brain CT or MRI is indicated for patients with suspected TIA or minor, nondisabling stroke within 24 hours of onset.
Brain MRI with DWI is the preferred study as it can detect small infarcts. CT, while is suboptimal, can exclude some TIA mimics such as tumour, subdural hematoma.
Vascular imaging
Vascular imaging is used to determine if there is an obstructive lesion in a larger artery supplying the affected territory.
Options include:
- MR angiography
- CT angiography
- Carotid duplex ultrasonography
- Transcranial Doppler ultrasonography
Cardiac evaluation
Cardiac monitoring should be done in patients with suspected emboli-related TIA.
- 12-lead ECG
- Echocardiography (if no etiology has not been identified)
Bloodwork
- CBC
- PT and PTT
- Electrolytes and creatinine
- Fasting blood glucose, A1C, lipids
- ESR/CRP (if inflammatory stroke suspicion)
Differential
Red Flags / Complications
The complication/sequelae of TIA is recurrent stroke.
- Highest risk in 48 hours after TIA (40% of 90 day risk)
- Highest risk associated with vascular pathologies (rather than cardiac or nonvascular TIA).
Management
Triage and Admission
Whether in-hospital observation is necessary is unclear. The guiding principle is the risk of recurrent stroke is highest in the 48 hours following the TIA.
It is generally recommended to keep the patient in hospital (whether admitted or in emergency department observation room) if any of the following are present:
- High risk of early stroke following TIA suggested by:
- Presence of acute infarction on DWI
- ABCD2 score ≥4
- Ipsilateral large vessel stenosis ≥50%
- Recent TIA within the last month
- Subacute stroke on CT
- Acute cardiac process (eg. arrhythmias, pathologic murmur, recent MI)
- Presence of etiology of brain ischemia that can be treated
- Uncertainty that the diagnostic workup can be completed in an outpatient setting
- Concurrent serious acute medical issues
Initial Management
If the patient does not have a known cardioembolic source, antiplatelet therapy is indicated once hemorrhagic stroke is ruled out.
- High risk: dual antiplatelet therapy - aspirin 81 mg plus clopidogrel 75 mg PO daily; loading dose is typically given
- Low risk: aspirin monotherapy 162-325 mg PO daily
Exceptions include:
- Patients who are on oral anticoagulation
- Patients who require new oral anticoagulation (eg. atrial fibrillation)
Secondary Prevention of Stroke
Intensive medical management
Medical management should be aggressively used to reduce risk. Strategies include:
- Treatment of hypertension
- High-intensity statin
- Evaluation and treatment of obstructive sleep apnea
Lifestyle modifications include:
- Smoking cessation
- Exercise
- Low-salt/Mediterranean diet
- Weight control
- Elimination or reduction of alcohol consumption
Large artery disease
Additional secondary prevention for large artery disease include:
- Revascularization
- Artery stenting
Atrial fibrillation
Patients with atrial fibrillation and TIA should be on oral anticoagulation. This is consistent with atrial fibrillation management.