What is a Mini Stroke (Transient Ischemic Attack)
A mini stroke, or transient ischemic attack (TIA), is a brief episode of neurological dysfunction caused by focal brain, spinal cord, or retinal ischemia, with clinical symptoms typically lasting less than 1 hour, and without evidence of infarction. 1
Evolution of TIA Definition
- The traditional time-based definition classified TIA as neurological symptoms lasting less than 24 hours, but this has evolved with advancements in neuroimaging 2
- Modern brain imaging has revealed that many patients with symptoms lasting less than 24 hours actually have evidence of brain infarction 1
- The newer tissue-based definition emphasizes:
- Brief duration (typically less than 1 hour)
- Absence of infarction on imaging
- Focal nature of the neurological disturbance 1
Clinical Significance and Risk
- TIA is a medical emergency and an important predictor of future stroke 3
- The risk of stroke following a TIA is substantial:
- 8.8% at 7 days
- 11.6% at 90 days 1
- The greatest stroke risk appears within the first week after a TIA, emphasizing the need for urgent medical attention 2, 1
- In patients with symptomatic carotid disease, the 90-day risk of ipsilateral stroke rises to 20.1% 1
Common Symptoms
- TIA symptoms mirror those of ischemic stroke but are temporary 4
- Common presentations include:
- Unilateral limb weakness
- Speech disturbances
- Sensory symptoms
- Visual disturbances (including monocular blindness which is more common in TIA than stroke)
- Gait difficulties 4
- Some symptoms are more specific to TIA:
- Monocular blindness (amaurosis fugax)
- Limb shaking (almost exclusively in TIA patients) 4
Risk Factors
- Family history of stroke or TIA
- Age above 55 years
- Male sex (higher risk than females)
- Hypertension
- Diabetes mellitus
- Tobacco smoking
- Dyslipidemia
- Race/ethnicity 5
Diagnostic Approach
- Modern imaging plays a crucial role in differentiating TIA from stroke 1
- Recommended diagnostic workup includes:
- Neuroimaging (preferably MRI with diffusion sequences) within 24 hours of symptom onset
- Noninvasive imaging of cervical and intracranial vessels
- Electrocardiography and cardiac monitoring
- Echocardiography in patients with undetermined vascular etiology
- Routine blood tests 6
Clinical Pitfalls and Caveats
- TIA symptoms are often evaluated based on patients' subjective reports, which can be less precise than objective assessment of stroke symptoms 4
- Several conditions can mimic TIA symptoms, including:
- Syncope
- Isolated dizziness
- Drop attacks
- Global amnesia 7
- These "TIA mimics" require careful history taking, examination, and appropriate imaging tests to differentiate from true TIAs 4
- Recognition of TIA symptoms may differ according to race, sex, education, and physician specialty, highlighting the importance of education for both the general population and healthcare providers 4
Importance of Urgent Evaluation
- TIA should be treated with the same urgency as acute stroke due to the high early risk of subsequent stroke 3
- Hospitalization should be considered for patients who:
- Present within 72 hours of symptom onset
- Have an ABCD2 score ≥3 (indicating high risk of early recurrence)
- Cannot complete evaluation rapidly on an outpatient basis 6