Stroke occurs when a blood vessel to the brain is blocked by a clot or bursts, cutting off oxygen and blood to part of the brain. It is a leading cause of death and disability. Every minute of untreated stroke, the brain loses neurons and tissue. However, early treatment within a few hours can reverse stroke in many patients. Signs of stroke include sudden weakness, numbness, trouble speaking - and it is crucial to immediately go to the hospital for treatment and not wait for potential improvement. With modern interventions like clot-busting drugs or removing clots through interventional techniques, blood flow can be restored and the brain tissue salvaged to fully or partially recover from stroke.