DR. ROBERT GUTHRIE
Stroke, or cerebrovascular accident as it is properly known, is a common manifestation of the diseases of the arterial system that I have been discussing in previous columns. Stroke involves a blockage in the arterial system that supplies blood to the brain, or a bleeding (hemorrhage) from one of the arteries into the brain tissue itself, with either of these damaging the brain tissue.
In the United States, we have about 800,000 strokes each year, with the majority, around 600,000 of them, being the initial or primary stroke in that patient. The remainders are recurrent or secondary strokes in people with a previous stroke. Stroke is a relatively common disorder, ranking as the third leading cause of death in the United States with about 140,000 per year, behind only heart disease and cancer. Fortunately, the death rate for stroke has dropped dramatically, with a reduction in fatal strokes of about 60%, since 1970. This reduction in stroke mortality parallels the reduction in heart disease mortality seen over the same time period. These changes reflect the progress in treating high blood pressure that began in 1970, along with the other health measures such as cholesterol reduction, the dramatic decrease in smoking, and improvements in diet and exercise seen in the last several decades.
In contrast to heart disease, stroke rates vary between different American ethnic groups. Specifically, the rates of both fatal and not fatal stroke are noticeably higher in African American patients. Most likely, this increase is directly related to the fact that high blood pressure occurs at a younger age and is much more severe in African Americans. This unfortunate medical issue simply means that African American patients and their physicians need to devote special time and attention to controlling blood pressure in their community.
Elevated blood pressure is clearly the most important risk factor for stroke. Fortunately, with the wide variety of medications that control hypertension, this risk is not difficult to control. Advancing age is another risk factor, but that is something we cannot treat. A further risk factor is elevated cholesterol, and studies show that the cholesterol lowering statin medications (simvastatin, Lipitor®, and Crestor® for example) reduce risk of stroke. Other risk factors are more difficult to manage, often requiring significant personal lifestyle improvements. I think we are much better off if we make significant efforts to control these potential problems by aggressive management of these lifestyle issues early in our lives, rather than trying to repair the damage from them after we have developed medical problems. However, this is often easier said than done.
Lifestyle measures to reduce recurrent stroke:
- no smoking
- control of diabetes (if present)
- dietary control and increased physical activity
- limited alcohol consumption
- reduced psychological stress, if possible
Even though stroke has much less impact on society than the various forms of heart disease do, people are usually much more afraid of suffering a stroke than a heart attack. This fear is clearly driven by the fact that most of us have seen the disability caused by strokes, including paralysis and loss of muscle control, the inability to speak or understand speech, and other problems related to brain functioning.
STROKE PATTERNS, PREVENTION, AND TREATMENT
While strokes affect older patients more often, when we do see a stroke in a younger person it is usually due to bleeding (a hemorrhage) from a congenital abnormality, a problem the patient was born with, in the one of the arteries supplying the brain. These defects are so rare that it is not reasonable to look for them until the patient experiences symptoms. Hopefully, symptoms will be mild enough to allow time for a proper diagnosis to be made and for surgery to correct the blood vessel defect before a tragic stroke happens. Symptoms include a dramatic and unusual headache and usually some other signs of brain disturbance.
In our efforts to avoid the initial stroke in any of our patients, the pivotal action patients and physicians can do is diagnose and treat high blood pressure. As I stated in the previous column, as we age nearly everyone develops hypertension. High blood pressure is confirmed by careful blood pressure measurements in the doctor’s office, followed by appropriate medication therapy to reduce and control the blood pressure.
While many of us want to avoid going onto medication treatment for high blood pressure, sometimes delaying therapy, it is wiser to remember the damage that can occur from a stroke as the result of poorly controlled blood pressure. Also, it is important to remember that most high blood pressure patients require multiple medications, often three or four, to properly control it. Therefore, do not hesitate if your physician tells you to begin taking another medication to control it. Remember that all studies have shown that lowering the blood pressure into the normal range clearly reduces stroke.
Whether other medications can reduce the risk of an initial stroke in an otherwise healthy patient is a point of disagreement among physicians. The statins, as the cholesterol lowering drugs are called, have been shown to reduce stroke in patients with existing heart disease. Reduction of stroke in patients without preexisting heart disease or stroke was seen in a study with aggressive cholesterol lowering with rosuvastatin (Crestor®).
Aspirin has drawn much attention as a preventive treatment and a number of studies have shown the use of aspirin, in a variety of doses, to reduce the risk of initial heart attack or stroke. However, recently some have pushed back against the widespread use of aspirin in patients yet to have a stroke or heart attack. They assert that risk of bleeding from the aspirin, mainly in the stomach and digestive system but also as a bleeding stroke in the brain, outweighs the benefit. I personally disagree with that contention. In my opinion, that belief focuses on much older studies that examined the use of much higher doses of aspirin than we use now, and those higher doses produced the bleeding problems. I think that judicious use of aspirin (81 mg dose) is appropriate if the patient is at risk for heart attack or stroke (i.e., someone with hypertension or diabetes) and does not have a history of bleeding problems. Everyone does need to recognize that the bleeding risk is there, and to monitor for it. Also, for reasons that we do not understand, heart attack and stroke reductions from preventive aspirin therapy are more marked in men and less dramatic in women.
Other than controlling blood pressure along with cholesterol reduction using a statin and possibly taking a daily 81 mg aspirin, prevention of a first stroke involves a healthy lifestyle – no tobacco, good exercise habits, and proper diet.
In many patients, the initial presentation of disease in the arteries affecting the brain is a transient ischemic attack (TIA). This involves a loss of some form of neurological or brain function for a brief period of time. Usually this lasts only a few hours but perhaps as long as 24 hours. While this event clears quickly, it can be an indication of potentially severe problems. A patient with a TIA requires an aggressive work- up, with special attention to the arterial system supplying the brain. A CT scan and/or MRI of the brain to determine if a stroke has occurred are essential. In addition, a careful evaluation of the carotid arteries in the neck that supply blood to the bulk of the brain is necessary. Many TIAs occur from small flecks of cholesterol plaque that break loose from partial blockages in the carotid arteries running up the front part of the neck. These flecks travel up to the brain and produce the transient symptoms of the TIA. Partial blockages in the carotid arteries are evaluated by ultrasound tests, or by CT or MRI imaging of the flow in the arteries themselves. If significant blockages in the carotid arteries are discovered, deciding whether they should be managed by medications or by surgery is a complicated question.
If a patient with blockages is not a candidate for surgery, or if no blockages are found, medication therapy for stroke prevention is always indicated. Medication therapy for a TIA is not significantly different than what is used for prevention of a recurrence after the patient has had a completed or actual stroke.
Medication therapy for a TIA or stroke is directed at reducing the stickiness of the platelets, components of the blood responsible for initiating the complex process that leads to clotting. Research has shown there are several mechanisms in the platelets that activate them and start the clotting process. Inhibiting these platelet activation mechanisms reduces the likelihood of a small or even large clot in the artery. Several medications and one combination medication have been shown to significantly reduce this platelet stickiness and reduce further TIA or strokes. These anti-platelet medications are the cornerstone of medication therapy for TIA and stroke.
The initial medication question in a patient with a new TIA or stroke is whether they had been taking a daily aspirin as a preventive. If the patient has not been taking a daily aspirin, then initiating a daily dose of 81 mg is appropriate, assuming that the patient is not allergic or has a history of intestinal bleeding. However, if the patient was already taking a daily aspirin, just continuing the aspirin without alteration is not enough. By having an event like a TIA (or stroke) while taking a daily aspirin, the patient has to be regarded as an aspirin failure. Aside from aspirin, Aggrenox® and clopidogrel (Plavix®), two other anti-platelet medications are used. Aggrenox® is a twice daily combination of low dose aspirin with dipyridamole, a second drug shown to inhibit platelet function. Aggrenox® has been studied in both TIA and stroke patients, so its effectiveness has been proven in both aspects of this disease process. Clopidogrel (Plavix®) inhibits a different mechanism of the activation of the platelets. It has not been studied directly in TIA, but it has been shown to be better than aspirin at reducing recurrent stroke. Therefore, its effectiveness in TIA is presumed because of its effectiveness in reducing recurrent stroke in patients who experienced a stroke while on aspirin. However, research has shown that if a patient has a stroke while already on aspirin, clopidogrel (Plavix®) should be substituted for aspirin, rather than combining them together (like we do in patients with heart attack). Another crucial diagnostic question, seen primarily in patients with completed strokes, is whether the patient has a particular type of abnormal heart rhythm called atrial fibrillation. Atrial fibrillation requires a different type of medication management.
ATRIAL FIBRILLATION MANAGEMENT
When a person is afflicted with a stroke, prompt medical attention is indicated. In our present era, about 80% of strokes are ischemic meaning blood flow to a particular part of the brain is blocked by a clot or a fragment of cholesterol from a larger artery. About 15% of strokes are hemorrhagic, caused by the rupture of a blood vessel supplying a particular part of the brain—leaking blood into the surrounding brain tissue. 5% are subarachnoid hemorrhage, which is a different kind of bleeding rupture into a different area of the brain. Of the ischemic strokes seen currently, about 15% are due to atrial fibrillation.
Atrial fibrillation is an abnormal heart rhythm in which two small chambers on the top of the heart ( the left and right atrium) are twitching rather than contracting regularly. This lack of effective contraction causes irregular heartbeat and allows the blood to pool in the twitching (not contracting) atria, allowing clots to form. Periodically, a portion of those clots can break loose and float through the arterial system into the brain, blocking blood supply and producing
an ischemic stroke where it lodges. Therefore, when a new patient presents with a stroke, careful evaluation of their heart rhythm is indicated to see if atrial fibrillation is the cause. This type of heart rhythm can be intermittent, coming and going spontaneously. Thus, its detection often requires intensive monitoring, frequently meaning that the patient will need to wear an electronic monitor for 24 hours or even 30 days.
TIMELY RESPONSE TO SYMPTOMS
Like a TIA, a new stroke is an emergency event, usually requiring hospitalization. Some of the more noticeable ischemic strokes require rapid transfer from the Emergency Department to the catheterization lab to inject an anticoagulant, or a clot buster, into the affected artery in the brain. Rapid transportation to the emergency department of a hospital equipped for this type of specialized treatment is required. As mentioned earlier, a new stroke patient needs an MRI of the brain, with a CT scan a less desirable alternative, to identify to presence, type, and location of the stroke. Many patients, particularly those with the typical ischemic stroke, will also need an MRI or CT exam to evaluate the arteries supplying blood to the brain. Frequently called a MR angiogram or CT angiogram, this test will help identify the small number of stroke patients that might benefit from surgery on the arteries supplying blood to the brain as a preventative measure.
For the patient who suffers a stroke (or the transient TIA), the initial symptoms can vary from extremely striking to relatively subtle. The symptoms are, of course, directly related to the area of the brain that is affected by the stroke, and the type of stroke that occurred. Subarachnoid hemorrhage bleeding stroke, the rarer of the two, presents primarily as a severe headache unlike any felt by the patient before. This can be a difficult diagnosis for both the physician and patient, many times requiring a great degree of careful evaluation by the physician. In the more typical stroke presentation, the patient and their family can often recognize the muscle weakness— often arm, leg, or facial, depending on the area of the brain that was damaged. This sudden weakness is usually noticed when the person awakens in the morning, a timing issue for stroke not clearly understood. Certain strokes will affect the special areas on the left side of the brain that control speaking, understanding (recognizing words), or expressing words and speech, such as remembering the words that the person wants to say. Damage to these control areas of the brain can lead to extremely frustrating disabilities.
STROKE WARNING SIGNS
- Sudden numbness or weakness of the face, arm, or leg, especially on one side of the body
- Sudden confusion, trouble speaking, or understanding
- Sudden trouble seeing in one or both eyes
- Sudden trouble walking, dizziness, loss of balance, or coordination
- Sudden, severe headache with no known cause
From the National Stroke Association
In other strokes, the symptoms can be much more subtle. As we have controlled blood pressure better in recent decades, small or mild strokes are more common than the massive ones we saw 30 years ago. If there is an ischemic (arterial blockage) stroke in the thalamus, a small area of the lower brain that contains the nerve pathways between the brain and the body, even small blockages can produce dramatic symptoms. In contrast, the more primitive parts of the brain stem are supplied by the vertebrobasilar artery going up the back part of the lower brain— separating it from the rest of the brain, which is supplied by the carotid arteries going up the front of the neck. Blockages in the vertebrobasilar artery can present very different symptoms, such as garbled speech, that may not be obvious to the patient or even the physician.
TREATMENT AND THERAPY OPTIONS
If someone has been unfortunate enough to experience a stroke, after going through the various evaluations discussed earlier, focus then moves to what we need to do to improve and also to avoid another stroke. Starting treatment for specific disabilities, such as physical therapy to improve their walking or strength training for arm weakness, is an initial step. Also, speech therapy can assist in improving speaking and cognitive or thinking skills and occupational therapy can improve a patient’s ability to care for him or herself.
In the long term, proper medication therapy in patients with a previous stroke is extremely important. As with TIA, medication to reduce the stickiness of the blood platelets is vital. If the patient had not been taking a daily aspirin as a preventive treatment, then low dose aspirin is an effective anti-platelet therapy. Studies have shown that two other alternate medication treatments, either clopidogrel (Plavix®) alone or Aggrenox®, as we discussed earlier in the section about TIA.
Beyond the anti-platelet therapy discussed above, several other medication therapies are also mandatory. Proper control of blood pressure is critical. Most stroke patients have a history of high blood pressure, and aggressive control of blood pressure is extremely important in reducing the risk of another stroke. Also, studies have shown that aggressive control of blood cholesterol is also essential. The statins, as the cholesterol lowering drugs (simvastatin, Lipitor®, and Crestor®) are called, are doubly protective in patients with previous stroke. Firstly, the statin drugs reduce the risk of another stroke. Once you have already had a stroke, the risk of a second stroke goes up dramatically. Secondly, it is surprising to many patients and physicians that most patients with a previous stroke die from heart attack, rather than die from a follow up stroke. The statin drugs are extremely effective in reducing heart attack risk. Therefore, I would recommend that the treatment target for the LDL (bad cholesterol) in stroke patients should be less than 70 mg/dl, the same low target level as if the patient had had a previous heart attack.
In my previous column in Colliers, I expressed doubts that the increasingly popular use of fish oils, or Omega-3 supplements, would actually reduce heart attack risk. Just recently, a very large, multi-year study of the use of Omega-3 supplements was released. The Omega-3, or fish oil, supplements were found to be worthless in preventing heart attack, stroke, and death from heart disease. This is a crucial study that supports my contention that these agents are of no value.
In the group of patients that are found to have atrial fibrillation, the treatment is more complex. Research has shown that medications, different from anti-platelet drugs like aspirin, can reduce the formation of clots in the atria at the top of the heart. For a number of years, we have used warfarin (Coumadin®), to reduce the formation of clots and thus the risk of stroke. Warfarin is an old product, developed in the 1950s. It is inexpensive, but difficult to use safely.
I always joke to the patients that it is the same ingredient in rat poison! Warfarin requires very careful monitoring, because too high a dose can lead to dangerous bleeding risks, and too small a dose will not prevent strokes effectively. Patients on warfarin need to have their blood drawn every three or four weeks to monitor and adjust the warfarin dose.
In the last year, newer agents that reduce the risk of forming clots in the atria have been introduced to the market. These new agents, led by PraDaxa® (Dabigatran), with Xarleta® (rivaroxaban) recently joining it on the market, offer a very different choice. Though the new agents are more expensive, they do not require the frequent regular monitoring or repeat blood drawing like warfarin does. PraDaxa® appears to be somewhat more effective in stroke prevention than warfarin with less risk of bleeding problems from the medication. While there is still some debate over when to use PraDaxa® or the other newer agents, it appears to me that the momentum to move away from the difficult to use warfarin and replace it with one of these newer agents will be very powerful.
Stroke, in spite of significant improvements in the last several decades, remains one of the major health problems facing the American public today. Several medications, including those to control blood pressure and cholesterol, possibly aided by taking a low dose aspirin, can reduce our risk of an initial stroke. If you have already had a stroke, additional medications instead of aspirin may be necessary, while complete control of blood pressure and cholesterol are extremely important. In all aspects of stroke prevention, proper lifestyle, including not smoking, proper diet and weight control, and reasonable exercise are the vital first line of defense. Because the damage from stroke can be so severe, realizing this and forming healthy habits prior to problems arising is very important.
ABOUT THE AUTHOR
Robert Guthrie M.D. is both a family physician and a general internist. He currently serves as Professor Emeritus of Emergency Medicine at the Ohio State University. He has published one book, numerous medical articles, has lectured extensively nationally and internationally, and been a long-term participant on local and national radio broadcasts. His column discusses a wide variety of health topics of interest to the general public. Questions, comments, or topic ideas may be sent in to firstname.lastname@example.org.