How do you know if you had a mini stroke?

By history: Mini strokes don't cause permanent damage, so they don't show up on mri. Diagnosis is by history- temporary loss of nervous system function, causing numbness or weakness, drooping of half of the face, trouble forming or finding words, trouble reading or understanding, etc. It can be hard to tell from migraine, as that can cause similar symptoms. Mini-strokes are warnings, so see a doctor!

Misconception: What people often call a "mini-stroke" is a transient ischemic attack which is just that-transient, it doesn't leave disability or imaging evidence. A non-cortical stroke in the white matter can go un-noticed until they add-up and cause memory loss and cognitive dysfunction. A cortical stroke, unless it was very small or in the front of the brain will usually cause some sort of symptom.

TIA: Diagnosing ministroke or TIA is not staight forward, sometimes you may have a small spot in your brain in mri( in dwi ), but the DX is mostly based on other clinical findings and symprtoms. Using Aspirin can lower the chance of getting tia.