What is a Stroke and what is a Transient Ischemic Attack (TIA)?A stroke or cerebrovascular accident (CVA) is sudden death of brain tissue resulting in symptoms that last for more than 24 hours. It is usually caused by a vascular problem, either a bleeding artery or vein in the brain or a blockage in an artery that supplies brain tissue. If the symptoms subside within 24 hours the patient is said to have suffered a TIA. A stroke or TIA may involve one or more of the following symptoms:
- • Numbness on one side of the body
- • Weakness, paralysis or loss of coordination on one side of the body
- • Drooping on one side of the face or mouth
- • Blindness or loss of part of the vision in one eye that typically is described as like a shade being drawn over the eye. The medical term for this is amaurosis
- • Loss of speech or garbled speech
- • Inability to write or understand writing
- • Episodes of memory loss
- • Loss of consciousness
The commonest cause of stroke or TIA is a blockage in the internal carotid artery. There are two carotid arteries, one on each side of the neck. These are the main arteries to the brain. Atherosclerotic plaque commonly develops in these arteries at the bifurcation or point where they divide into the artery to the brain (the internal carotid artery) and the artery to the face (the external carotid artery). Plaque can decrease blood flow to the brain and hence a TIA or stroke by narrowing the artery or by breaking loose and blocking an artery in the brain itself.
How will I know that I have carotid plaque?
Your doctor may hear a noise in your neck called a bruit. A TIA or stroke is also often evidence. However, most often the plaque is asymptomatic when it is detected by a noninvasive test called a duplex scan. Patients who may benefit from one of these tests are those at risk for atherosclerosis:
- • Elderly patients
- • Diabetics
- • Those with known atherosclerosis elsewhere
- • People with high cholesterol
- • Patients with high blood pressure
- • Smokers
- • Those with a strong family history of stroke
What is a Duplex scan?In order to get a picture of where the blockage is, very advanced machines using ultrasound can painlessly and non-invasively produce pictures showing the blood vessels and the blood flowing through them. This process is a little like radar. The test is called a duplex or ultrasound scan. When performed in an accredited vascular lab such as ours, this test should be all that is necessary to diagnose and plan treatment.
What is an arteriogram and will I need one?Blood vessels do not show up on regular X-rays. Accordingly, in an arteriogram the doctor will insert a needle into the artery and inject a special dye. This will allow detailed pictures of the inside of the arteries. The needle is usually inserted via the groin or femoral artery. A sensation of heat often accompanies the dye injection however, local anesthesia and sedation is used to eliminate pain. The procedure usually takes about half an hour. After it has been completed the patient is required to lie flat for about 4 hours in order to prevent bleeding. The procedure is performed in an X-ray facility usually in a hospital. Unfortunately, arteriograms of the carotid arteries can cause stroke in as many as 1% of patients. In some instances a Magnetic Resonance Angiogram or MRA can replace the need for arteriograms. MRAs are performed using high energy magnets and result in pictures of the blood vessels and brain very similar to those obtained by arteriograms and CAT scans. They are completely safe and painless but cannot be used in patients who have steel implants such as pacemakers. Some patients also become claustrophobic in the scanners. We have pioneered doing surgery without arteriograms thus avoiding this risk in most patients.
Are their medications that can prevent a stroke?There are no medications that can make the plaque disappear although in some patients strict control of cholesterol can reduce plaque.
However, some TIA and strokes are due to dislodgement of blood clots from the plaque into the brain. These blood "clots" are really aggregations of small blood cells called platelets. Using anti-platelet medication such as Aspirin may prevent this aggregation and subsequent TIA or stroke. Newer more effective medications are being added every year such as Aggrenox® and Plavix®. In patients with mild plaque these medications should be considered. However, side effects can occur and you should discuss the potential risk/benefit with your doctor.
What about surgery and what is an endarterectomy?The surgical procedure to remove plaque is called a carotid endarterectomy. Although usually quite safe, some patients will suffer a stroke, nerve damage or heart attack from the procedure. Accordingly, the benefits of this procedure will depend greatly on the skill of the surgeon. It is imperative that you ask your surgeon about his or her experience. National statistics suggest that the stroke rate approximates 3-5% and the heart attack rate 1%. However our stroke rate is only 1.3% and the heart attack rate 0.5%. This is in keeping with the best-reported statistics in the world and is the reason we are invited to present our data at national and international conferences.
A major study of stroke risk has been conducted under the auspices of the National Institute of Health. This study concluded that surgery is more effective than medication and should be considered for patients who have had a TIA or recovered stroke and a blockage of >70%. A second study performed by the Veterans Administration also suggests that some patients, especially men who have an asymptomatic blockage of >60% should also be considered for endarterectomy.
How is endarterectomy performed and what is the recovery?The operation can be performed under general or local anesthesia. It takes about an hour. The plaque is cut out of the artery and the artery repaired. Most patients are sent to a regular ward following surgery and are discharged the next morning. There is very little discomfort. Normal activity can be resumed but heavy exercise and driving is limited for one week. Thereafter, full return to normal activity is encouraged, including activities such as golf. Most patients will continue taking aspirin after the procedure. Follow up duplex scans will be performed on a 6 monthly basis to assess for the small chance or recurrent plaque or scar tissue that can also re-narrow the artery. This occurs significantly in about 4% of patients.
What about angioplasty or ballooning my arteries?Balloon angioplasty of coronary heart arteries and leg arteries has been proven to be effective. Accordingly, studies are under way to see if this technique can be applied to the carotid arteries. However, it is important to realize the difference in risk when the carotid arteries are treated in this manner. If a small piece of plaque breaks loose and goes into the brain a fatal stroke can result. At present the early results suggest, not surprisingly, that angioplasty carries a higher risk of stroke than surgical endarterectomy. Advances in techniques may improve results, but currently angioplasty is considered experimental and should only be performed as part of an ongoing National Institute of Medicine study trial. On occasion however we will use it for certain patients who would be at increased risk from surgery. These include patients who have had radiation treatment for neck cancer.