Cerebral thrombosis is the most common type of stroke. It occurs when a blood clot (thrombus) forms and blocks blood flow in an artery bringing blood to part of the brain. Blood clots usually form in arteries damaged by atherosclerosis .

One identifying feature of cerebral thrombotic strokes is that they often occur at night or first thing in the morning, when blood pressure is low. Another is that very often they're preceded by a transient ischemic attack, also called a T.I.A. or "mini-stroke."