What Is a Mini Stroke?
With a mini stroke, or transient ischemic attack, parts of the brain temporarily lose blood supply, resulting in stroke-like symptoms. Like an actual stroke, a TIA can cause impairment in any area of the brain including speech, mobility and memory. Unlike an actual stroke, the effects only last a few minutes to a few hours, and the condition resolves itself without medical intervention. Additionally, once blood flow is restored to the affected area, functionality returns.
TIAs are warning signs for future strokes and the risk of stroke increases in the days and weeks following TIA. The most common causes of TIA are blood clots (in the form of thrombi or emboli), and hemorrhage.
Thrombi
A thrombus is a stationary clot on a blood vessel wall. With TIAs, clots may form on the small arteries in the brain. These clots are usually caused by a combination of narrowing of the vessel and an accumulation of plaque on the artery wall. As the vessel narrows and the clot grows, blood supply to that area of the brain is cut off, starving the tissue for oxygen. However, the blockage may not be complete enough to cause a stroke or the blood vessels may grow collateral vessels, making it possible for blood to flow around the clot.
Emboli
An embolus is a thrombus that has broken off, traveled to a new location and become stuck. The emboli that lodge in the brain often originate in the heart and are formed through atrial fibrillation. In atrial fibrillation, the upper chambers of the heart shake, instead of maintaining a steady beat. This causes blood to pool and form clots. The constant motion of the heartbeat causes some of these clots to break off into the blood stream. These clots have the potential to block any vessel, anywhere in the body, but many make their way to the brain.
Hemorrhage
If a vessel has weakened walls it may rupture, causing bleeding or hemorrhage in the brain. When the vessel ruptures, tissue upstream from the rupture is starved for oxygen. In the case of a TIA, it's usually a smaller vessel that ruptures and the vessel is able to repair itself and stop the bleeding. The most common cause of vessel ruptures is hypertension, which not only leads to increased pressure in the vessel but can actually damage and weaken the vessel walls.
Tags: actual stroke, area brain, atrial fibrillation, blood flow, blood supply, causes blood, clots form