Ask Dr. Pat

Dr. Pat Consults: The Anatomy of a Stroke

Dr. Patricia Yarberry Allen is a collaborative physician who writes a weekly Medical Monday” column for Women’s Voices for Change.  (Search our archives for her posts, calling on the expertise of medical specialists, on topics from angiography to vulvar melanoma.)

This week, Dr, Pat has asked Dr. Baxter B. Allen, a third-year resident in Neurology at Weill Cornell Medical College/New York Presbyterian Hospital, to answer the questions of a woman whose husband could not believe he was having a stroke and refused to go to the hospital. What are the signs of a stroke, and what should you do when you suspect you might be having one?


Dear Dr. Pat:

My husband is only 65, and he had a stroke six months ago. He has high blood pressure and has had problems with occasional heart-rate irregularities, but they were not frequent and never caused him any real symptoms. When he woke up one morning, he was dizzy and could not walk straight. He was slightly confused, but did not think anything was wrong. He refused to go to the hospital, so I called our doctor, who told me to call an ambulance since my husband was certain that “nothing was wrong.” The neurologist at the hospital told us that he had had a stroke sometime during the night because of an obstruction in a blood vessel to a part of the brain. Even though my husband wasn’t a candidate for emergency medication to dissolve the clot, he was lucky. The damage to his brain was small, and with rehabilitation he is now almost back to normal. He saw a cardiologist and is on medication to control the heart-rate abnormality that was probably part of the cause of the stroke.

What causes strokes in general? Can strokes be prevented? Why didn’t my husband know that he had something seriously wrong after that stroke? What part of the brain is usually affected by a stroke?



Dr. Allen Responds:

Dear Marjorie:

I am sorry to hear about your husband’s stroke, but glad to hear that he’s almost fully recovered. There is a strong relationship between heart-rate abnormalities and strokes. Your questions are important ones, but given their complexity, these will be addressed over several upcoming posts. Today let’s focus on what happens in a stroke and what parts of the brain are affected.

Strokes are the fourth leading cause of death in America; they cause nearly 130,000 deaths annually. In addition, strokes cause significant disability and affect roughly 800,000 Americans in this way every year. The vast majority of strokes—roughly 85 percent—are ischemic, meaning that part of the brain is damaged because of a loss of blood flow and oxygen. The remaining 15 percent of strokes are caused by either bleeds into the brain (also called intraparenchymal hemorrhages) or bleeds into the area directly around the brain (the subarachnoid space).

This article will focus on what occurs in ischemic strokes, the most common signs and symptoms, and what you should do if you think a stroke has occurred.

What Happens?

Strokes are caused by many different things, but roughly 25 percent are cardioembolic (i.e. a clot breaks off from the heart and blocks a vessel in the brain; 25 percent large-artery atherosclerosis (plaques forming in the walls of the large arteries in the head or neck, leading to blockages), and 25 percent small-vessel disease. The remaining 25 percent are caused by a number of less common problems, or are cryptogenic, meaning that a cause is unable to be determined.

Cardioembolic strokes occur when a clot or other material breaks off from some part of the heart and is pumped through the blood into the arteries of the brain. These occur in patients with abnormal heart rhythms (most commonly, atrial fibrillation), heart attacks, and heart valve abnormalities (such as having a mechanical heart valve). Because of the well-known association between these issues and strokes, patients with known heart problems are frequently placed on blood thinners to decrease the risk of stroke. Unfortunately, these problems are often not discovered until after a stroke occurs.

Stroke(From National Heart, Lung, Blood Institute,

Large-artery atherosclerosis leads to strokes due to damage in the walls of the large vessels in the neck (internal carotid and vertebral arteries), or within the head (internal carotid, anterior cerebral, middle cerebral, posterior cerebral, basilar, and vertebral arteries). As with atherosclerotic disease of the heart, deposits of cholesterol and other products cause narrowing of the arteries. These narrowings, or plaques, can become 100 percent occluded over time, or small pieces of them can break off and cause a blockage further into the head. In some patients, if there is a significant enough blockage in the neck, surgery can be performed to decrease the risk of stroke; however, most patients are treated with medical therapy to stabilize and, hopefully, decrease the degree of narrowing.

Stroke 2(From National Heart, Lung, Blood Institute,

Small-vessel disease leads to small strokes that frequently go undetected. This is most common in patients with high blood pressure, diabetes, or a smoking history. The small arteries in the head and other parts of the body become thickened, stiff, and damaged over time; when this damage leads to complete occlusion of a small artery in the brain-—whether from a very small clot, from worsening inflammation, or from a spasm in the artery—a small stroke can occur.

Next Page: The signs and symptoms of a stroke

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  • roz warren February 2, 2015 at 8:46 pm

    Terrific information. Thanks.

  • Andrea February 2, 2015 at 7:40 am

    Very informative article. When my elderly dad says “I’m fine Im fine ” I will use the F A S T rule for sure. Thank you Dr Allen. The apple obviously does not fall far from the tree!!