Treatment of an ischemic stroke is the restoration of blood flow to the brain to prevent and minimize damage.  

A blockage is usually caused by atherosclerosis, an accumulation of "plaque" (deposits of fat) in the arteries that narrows them, reducing blood flow, or by blood clots in the arteries.  The plaque not only blocks the blood flow itself, it can also help create a clot because it forces the blood to flow abnormally.  A clot that stays in one place (usually the place it was formed) is called a thrombus.  A clot that breaks loose, travels to another spot, and wedges itself into a narrower blood vessel, is called an embolism.

The first indication that an artery may be blocked can be an abnormally loud, harsh noise coming from it, heard through a stethoscope during a physical examination. This noise is called a bruit (pronounced "bru-we").  The next step can be one or more tests to look at the arteries that feed the brain and measure the amount and type of blockage in them.  They're the same type of diagnostic imaging tests now used to diagnose a wide range of conditions, including heart problems.  They include: 

• Carotid arteriogram (also called carotid angiogram): This is an x-ray of the carotid arteries to look for blockages. A catheter (a small tube) is inserted through a small incision into a blood vessel and threaded up into the carotid arteries. A contrast dye is then injected into the catheter to make blockages more visible on the x-ray.
• Carotid ultrasound:  Many people are familiar with ultrasound imaging used with pregnant women to produce images of fetuses.  Similarly, carotid ultrasound produces pictures of the carotid arteries.  High-frequency sound waves are sent into the neck, pass through the tissue, and then bounce back.  The results are images that show any narrowing or clotting in the carotid arteries.
• Computerized tomography angiography (CTA):  Many people are also familiar with CT scanning (often called "CAT scanning") which produces detailed images of organs and tissues.  CTA is a form of CT scanning that uses dyes injected into the bloodstream to make blockages and other problems more visible. 
• Magnetic resonance imaging (MRI): This technique uses a strong magnetic field to create a three-dimensional view of the brain to look for the areas damaged by a stroke. 
• Magnetic resonance angiography (MRA) combines an MRI with an injected dye to better see the arteries in the neck and brain. It is used to determine if the stroke was caused by bleeding (hemorrhage) or other lesions and to define the location and extent of the stroke.

If these tests show that either of the two carotid arteries are narrowed, a physical intervention to remove the blockage may be needed.  When an individual has symptoms of a stroke or TIA from a carotid artery that is over 70% blocked, evidence suggests that those individuals should strongly consider undergoing an operation to remove the blockage.  If the individual has not had any symptoms from the severe blockage, or if the amount of blockage is less severe (50-70%), decisions about surgery should be individualized, depending on unique patient characteristics and preferences. 

The process of removing the blockage is called carotid revascularization.  Currently, one of two approaches is generally followed. 

One approach is an operation called a carotid endarterectomy (CEA).  The surgeon opens the affected artery and physically removes the blockage – the plaque, clot, etc. Studies show that this procedure reduces the risk of stroke and is especially helpful to people with severe blockages, even if they have no symptoms at all.  Although all surgery has general and specific risks (the specific risks for carotid endarterectomy is that the surgery itself might cause a stroke or heart attack), the risks for CEA are not great.

The second approach is known as carotid artery stenting or carotid angioplasty-stent (CAS) and may be more appropriate than surgery in some patients.  Angioplasty is the process of opening or widening a narrowed blood vessel. The procedure was first used in the 1970s to treat coronary artery disease; now it has been extended to other arteries, including the carotid artery.  A catheter is threaded up into the arteries.  A tiny balloon at the end of the catheter is inflated to open the narrowed blood vessel.  The process may also involve using a tiny umbrella-like filter (called a "distal protection device") at the end of the catheter to catch any particles that break free from the artery and prevent them from traveling to and blocking some other blood vessel.

A stent is an object put inside a blood vessel to keep it open and unblocked.  Today a stent is usually a tiny tube made of a metallic mesh that looks something like a wire cage or spring.  After a blocked blood vessel has been opened, a stent can be slid along the catheter and put in place to keep the vessel open.  Some stents are coated with medicines to help prevent further blockages.

While carotid stenting is a newer technique and still under investigation, current research has shown it to be as effective as carotid endarterectomy in some cases and a less invasive form of surgery.  Meanwhile, other new techniques to remove clots, such as catheter embolectomy (using a catheter threaded into one of the carotid arteries to remove clots) are being explored.