A stroke is caused by a sudden interruption in blood flow to the brain. Almost 80 percent of all strokes are ischemic (as opposed to hemorrhagic). Stenosis, which in the context of a stroke describes when a blood vessel is abnormally narrow, is usually the cause of an ischemic stroke, and atherosclerosis (also known as hardening of the arteries) is the buildup of fatty deposits, or plaques, that leads to this abnormal narrowing.
Narrowed arteries may not be wide enough to supply sufficient oxygenated blood to the brain. In addition, clots can form or a piece of the clot or plaque can break off and travel, lodging in a smaller artery and blocking blood flow.
If a person is shown to be suffering from an acute ischemic stroke, medicines known as thrombolytic agents, or clot-busters, may be administered to dissolve the clot and improve blood flow to the part of the brain being deprived. The medication tPA was first approved by the FDA in 1996 to treat strokes within hours of onset.
Recent studies have shown that tPA in combination with mechanical embolectomy can produce the best outcomes. In mechanical embolectomy, a neurosurgeon or interventional neuroradiologist threads a tiny tool through blood vessels starting from a small incision in the upper thigh into the blood vessel in the brain to physically clear the obstruction. (See The Lazarus Effect.)
Reviewed by: Dr. Philip E. Stieg
Last reviewed/updated: October 2020