Although the symptoms of a migraine and a TIA can be similar and difficult to discern between the two, there is a huge difference.
Migraines are episodes or attacks related to a genetic neurological disease. They can be frightening and painful, but are generally not harmful.
A TIA, often referred to as a mini-stroke, is a "transient ischemic attack" that lasts only a few minutes. It occurs when the blood supply to part of the brain is briefly interrupted. TIA symptoms, which usually occur suddenly, are similar to those of stroke but do not last as long.
If you ever feel that your migraines are worse than usual, or creating different symptoms, it's best for you to see your doctor or go to the emergency room immediately to be sure that it is a migraine, and not a TIA.