Stroke

Treatment of Ischemic Stroke and Transient Ischemic Attack (TIA)

Ischemic stroke is caused by a blood clot that blocks or plugs a blood vessel in the brain. About 80 percent of strokes are ischemic. They are divided into two types:

• Thrombotic (cerebral thrombosis) is the most common type of ischemic stroke. A blood clot (thrombus) forms inside an artery in the brain that is diseased or damaged by atherosclerosis (cholesterol-containing deposits called plaque), blocking blood flow.
• Embolic (cerebral embolism) is caused when a clot or a small piece of plaque formed in one of the arteries leading to the brain or in the heart, is swept through the bloodstream to lodge in narrower brain arteries. The clot plugs a vessel in the brain, cutting off the blood supply.

Transient ischemic attack (TIA) is a warning sign of the potential for a future stroke. By definition, the symptoms of a TIA may last up to 24 hours, but they often last only a few minutes. TIA occurs when the blood supply to part of the brain is briefly interrupted. TIA symptoms are similar to those of stroke but do not last as long. Most symptoms of a TIA disappear within an hour. About one-third of strokes are preceded by one or more TIAs that can occur days, weeks or even months before a stroke.

Treatment Options

Medications

Clot-dissolving medications
Much of the damage caused by an ischemic stroke (a stroke due to a blood clot in the brain) occurs in the first few hours. Injection of a clot-busting (thrombolytic) drug — such as a tissue plasminogen activator (TPA) — into the veins to dissolve a blood clot may increase chances of a full recovery compared with other treatment methods.

If used intravenously, therapy with clot-busting drugs for the treatment of an ischemic stroke must be started within three hours. After that, the risks of bleeding or other complications from this type of therapy begin to outweigh potential benefits. After three hours, these medications may sometimes be given directly into the site of the clot (intra-arterial therapy) by a neuroradiologist. With the diagnosis of an acute stroke, the patient or family members, and the doctor must work together to weigh the risks versus benefits of thrombolytic therapy.

Anticoagulants
Often called blood thinners, anticoagulants may be prescribed by physicians following a stroke. By reducing the ability of the blood to clot, they may help to keep blood vessels open and delivering oxygen and nutrients to brain cells.

Antiplatelet drugs
In addition to a stroke-preventive measure, these drugs may be administered during or immediately after a stroke to help prevent clot formation. While they work differently from anticoagulants, the result is similar. They help to keep blood vessels open and delivering oxygen and nutrients to brain cells.

Experimental medications

Neuroprotective drugs
During an ischemic stroke, complex chemical and electrical processes leads to the death of nerve cells. Neuroprotective drugs work to minimize the damage that results when brain cells are deprived of oxygen and nutrients. Although no neuroprotective agents are available commercially, several types of these drugs are in clinical trials for acute ischemic stroke. Like thrombolytics, most neuroprotectives need to be administered quickly after a stroke to be effective.

Surgery and other procedures

Carotid endarterectomy
This procedure is used to remove atherosclerotic plaque from the carotid (neck) artery when it is narrowed. The surgeon makes an incision in the neck, the artery is opened and the plaque is removed. In people with substantial blockages in the carotid artery who are good candidates for the surgery, the procedure may reduce the risk of ischemic stroke.

Revascularization (Bypass)
This technique is used to establish a new route for blood to reach the brain, usually by grafting another vessel to a cerebral artery.

Endovascular therapy
Endovascular therapy is a radiological procedure that is an alternative to surgery. Endovascular procedures are performed within the blood vessel. Mayo Clinic has extensive experience with this technique and has found it is an effective treatment in properly selected patients.

• Angioplasty and stenting
  Angioplasty can widen the inside of an artery leading to the brain. In this procedure, a balloon-tipped catheter is maneuvered into the obstructed area of the artery. The balloon is inflated, compressing the plaque against the artery walls. A metallic mesh tube (stent) is usually left in the artery to prevent recurrent narrowing. A doctor may recommend angioplasty for patients who are not good candidates for endarterectomy, or for narrowing in arteries that are not accessible with surgery.