Update on Stroke

Posted By SHL Librarian

Presented by: Greg Albers, MD
Director, Stanford Stroke Center
May 15, 2014

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About 780,000 Americans suffer from a stroke each year—someone every 45 seconds. It’s the fourth leading cause of death in the U.S. but the greatest cause of long-term disability. Most people do not die from a stroke but its effects cause more than half of all neurologic hospitalizations. The direct and indirect costs from lost work and lost productivity are enormous.

Though it can occur at any age, the risk of stroke doubles for each decade after age 55, and the aging Baby Boomer population is expanding the number of the most susceptible people.

“Stroke is incredibly common,” said Greg Albers, MD, director of the Stanford Stroke Center and the Coyote Foundation Professor of Neurology, who spoke at a presentation sponsored by the Stanford Hospital Health Library. “Almost everybody’s lives have been touched by stroke in one way or another.”

Stroke is defined as a brain injury that occurs from an abrupt disruption of blood flow to the brain. Ischemic stroke, the more common of the two types of stroke, is caused by a clot that blocks an artery in the brain. Hemorrhagic stroke occurs when a blood vessel breaks and leaks blood in or around the brain. Strokes can cause paralysis, language disturbances, coordination or balance difficulties, confusion, or vision loss.

Types of Stroke
An ischemic stroke occurs when a blood vessel becomes blocked with cholesterol deposits, a condition known as atherosclerosis. A thrombotic stroke is caused by a clot that forms inside a blocked blood vessel in the brain; an embolic stroke is caused by a clot that forms elsewhere in the body and travels toward the brain until it becomes lodged in a narrow artery. Since there’s no bleeding, ischemic strokes typically doesn’t hurt and many occurs during sleep therefore the exact time of onset is unclear. About 85 percent of strokes are ischemic and 15 percent are caused by hemorrhage.

The less common hemorrhagic stroke usually stems from years of hypertension (high blood pressure) that eventually causes blood vessel walls inside the brain to weaken and rupture.

“A blocked artery and a ruptured artery are two very different problems that require different solutions,” said Dr. Albers.

Vessel Network
Two carotid arteries supply blood to the front of the brain, and two vertebral arteries supply blood to the back of the brain. A loop of arteries at the base of the brain, called the Circle of Willis, helps determine how well the brain can compensate for a blocked vessel. Some people have a genetic advantage in which a complete Circle of Willis can provide a protective back-up system to compensate for a blocked vessel. The system is made less efficient by smoking or unhealthy lifestyle habits.

The junctions where these arteries come together at the Circle of Willis may develop weak spots that can balloon out, creating sacs called aneurysms that can leak or rupture.

About 25 percent of ischemic strokes occur because of atherosclerosis in the large vessels in the neck. About 20 percent are caused by a heart embolism, and another 20 percent stem from small vessel atherosclerosis in the brain. About one third are undetermined, creating a diagnostic and treatment challenge for stroke specialists.

Location, Location, Location
The symptoms of stroke depend on which vessel is blocked. A stroke in the anterior parts of the brain will often cause numbness, weakness, and partial vision loss. In the left hemisphere  it will typically cause language or speech problems; in the right side it can cause a condition called neglect, in which the person is unaware of his or her neurologic deficits. A stroke in the left hemisphere will affect the right side of the body, and vice versa. A stroke in the posterior part of the brain can lead to bilateral weakness, vertigo, double vision, or blindness.

Behavioral risk factors include smoking, alcohol abuse, diet, and inactivity. Contributing physiological factors include high blood pressure, high cholesterol, atrial fibrillation, diabetes, and prior stroke or a TIA.

A transient ischemic attack, or TIA, is a clot in the brain that dissolves before it has done any damage. A TIA does not cause disability, but the risk of a significant stroke within the next 48 hours is about 5 percent and a warning of more potential trouble ahead.

Control Factors
“Controlling high blood pressure is our most powerful tool for controlling stroke,” Dr. Albers said. “In general, the lower, the better”. Controlling blood pressure can reduce the risk of stroke by 30 to 40 percent.”

Multiple studies have shown that statins reduce risk of stroke in patients with coronary artery disease and high cholesterol. Dr. Albers cited the SPARCL study that found that a high dose of a statin medication reduced the risk of stroke and was well tolerated, with side effects (such as muscle aches) comparable to that of the placebo group.

Studies also have shown that quitting smoking can reduce risk by almost 50 percent within one year, and controlling cholesterol levels can decrease risk by about 20 percent. Dr. Albers suggested that for patients with atherosclerosis, LDL cholesterol (the “bad” cholesterol) should be lowered to below 80 to100 mg/dL.

After the cause of a stroke is determined, different medications are prescribed based on the type of stroke. For most patients with an ischemic stroke, regular use of an antiplatelet agent such as aspirin or clopidogrel (Plavix) can help prevent blood clots from forming. If atrial fibrillation is the cause, anticoagulants, such as warfarin (Coumadin), are typically prescribed.

New Options
While the FDA has approved the use of a clot-busting medication called tissue plasminogen activator (tPA) for up to three hours after a stroke, many people do not recognize the symptoms and do not make it to the emergency room in time. Dr. Albers and his Stroke Center associates typically give tPA up to 4.5 hours after the onset of certain kinds of stroke.

“The reality is that not everyone can make it to the emergency room during that ‘golden window,’” he said. “There’s only a small window of opportunity, so if you think you are experiencing a stroke, call 911 and go the emergency room immediately. You need to act quickly because we need to take some images and do some tests before starting treatment, and that takes time.”

About the Stanford Stroke Center
The Stanford Stroke Center was one of the first centers of its kind in the United States and was the first to be designated a comprehensive stroke center by The Joint Commission, a not-for-profit organization that accredits more than 15,000 health care organizations in the U.S.

The Center incorporates a multidisciplinary approach to stroke care. It’s staffed 24 hours a day with neurologists, neurosurgeons, radiologists, and rehabilitation experts, who use the latest technology when patients come in with signs or symptoms of stroke. In addition to utilizing cutting-edge technology for emergency stroke care, the Center is involved in studies to improve existing therapies and to develop new techniques for treating, diagnosing, and preventing stroke.

About the Speaker
Gregory Albers, MD is director of the Stanford Stroke Center and the Coyote Foundation Professor of Neurology and Neurological Sciences. A nationally known stroke expert, his research and clinical work focuses on the treatment and prevention of cerebrovascular disorders and the use of diffusion and perfusion MRI to expand the treatment window for ischemic stroke. Dr. Albers received his MD from University of California, San Diego, School of Medicine and did his internship, residency and stroke fellowship at Stanford. He is Board Certified in Neurology and in Vascular Neurology by the American Board of Psychiatry and Neurology.

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About Dr. Albers

Stanford Stroke Center

 

Latest Advances in Stroke Treatment

Posted By SHL Librarian

Presented by: Jeremy Heit, MD, PhD
Fellow, Neuro-interventional Radiology
Stanford University Medical Center
April 30, 2015

About 800,000 Americans suffer from a stroke each year—someone every 45 seconds. Stroke is the fourth leading cause of death in the U.S. but the greatest cause of long-term disability. Most people do not die from a stroke, but its effects cause more than half of all neurologic hospitalizations. The direct and indirect costs from lost work and lost productivity are estimated to run about $73 billion each year. May is National Stroke Prevention Month.

A stroke occurs when a blood vessel carrying oxygen to the brain suddenly bursts or becomes blocked and can cause paralysis, language loss, coordination or balance difficulties, and confusion. Ischemic stroke, the most common type of stroke, is caused by blockage from a clot in the carotid arteries of the neck or in the brain, similar to what occurs during a heart attack.

“When blood flow is interrupted, the effect is almost immediate,” said Jeremy Heit, MD, PhD, a fellow in Stanford’s Neuro-interventional radiology program, who spoke at a presentation sponsored by the Stanford Health Library.

Time Element
In an ischemic stroke, the area immediately affected by the blood loss—the core infarction—suffers irreversible damage. However cells in the surrounding area—the penumbra—may remain viable for several hours and have a good chance of being salvaged if blood flow to this region can be restored. Every second the brain survives without blood flow, damage is done. The faster blood flow can be restored, the more cells can be saved, causing less neurological damage and better patient outcomes.

“If the penumbra is not saved quickly, there is likely to be more damage,” he said. “As the number of damaged brain cells grows, the complications increase. Restoring blood flow rapidly is the best chance for a good outcome. Our goal is to get the vessel open as quickly as possible.”

There are several options for reperfusion, or restoring blood flow through blocked arteries. A clot-busting medication called tissue plasminogen activator (tPA), which was introduced 20 years ago, has been shown to open up vessels if introduced within four hours on stroke onset. People who receive treatment within four hours are more likely to recover.

But the window of opportunity after a stroke is small—and many people don’t even realize they are having a stroke or don’t make it to the emergency room in time. As a comprehensive stroke center, Stanford has been instrumental in developing new treatments for stroke patients who are not able to receive tPA.

New Options
A more recent option is known as a mechanical thrombectomy in which the clot is manually removed using endovascular (minimally invasive) surgical techniques. A catheter is introduced at the femoral artery at the groin, and neuro-interventionalist uses X-rays to navigate the catheter up to the brain. An retrievable stent or suction device is then used to physically pull out the clot. These promising mechanical technologies can be done in less than 20 minutes and show benefit up to eight hours after the onset of a stroke.

“The technology is improving rapidly,” said Dr. Heit, “but we need to know what’s going on in the brain before we act so we can identify the patients who are most likely to have a good outcome with this therapy.”

Dr. Heit, who will join the Stanford faculty next year, is an expert in different imaging tools for assessing where the core of the stroke is located and the areas at risk in the penumbra. Using advanced magnetic resonance imaging (MRI), for example, he can identify the areas at risk and pinpoint the exact location of the clot. Using another imaging system called computed tomography, he can conduct a brain CT scan to show bleeding in the brain or damage to the brain cells. Often he will combine MRI with CT to create the most accurate picture of the brain that neuro-interventionalists can use as a map to deliver therapy. The same systems can show response to treatment in just minutes.

“Our challenge is to know who will most benefit from this treatment,” he said. “There are specific questions we have to ask: Where is the clot? How big is the existing stroke? A good candidate will have a small core, have a large amount of tissue at risk, and have a clot that can be reached. Outcomes are better if the patient is selected based on this criteria.”

Recent studies have shown improved outcomes using an endovascular approach over medical treatment with tPA. And now neurologists and neuro-interventionalists are using the two methods in conjunction with excellent results. At Stanford, blood clot removal techniques can be used in 80-85 percent of patients, which maximizes the odds of a good outcome after a stroke, he said.

Dr. Heit emphasized that as a neuro-interventional radiologist, he uses advanced imaging and guidance techniques for both diagnosis and treatment. He is part of a multidisciplinary team made up of neurologists, neurosurgeons, neuroradiologists, intensive care physicians, nurses, and rehabilitation experts who use the latest technology when patients come in with signs or symptoms of stroke.

Stroke Warning Signs

  • Sudden numbness or weakness of the face, arm, or leg, especially on one side
  • Confusion, trouble speaking or understanding
  • Partial loss of vision in one or both eyes
  • Difficulty in walking, dizziness, loss of balance or coordination
  • Sudden, severe headache

What To Do In Case of Stroke

If you spot the signs of stroke, think FAST:

  • Face drooping: Ask the person to smile. Is the smile uneven?
  • Arm Weakness: Is one arm weak or numb?
  • Speech Difficulty: Is speech slurred? Is the person unable to speak or hard to understand?
  • Time to call 9-1-1: Get the person to the hospital immediately. Check the time so you’ll know when the first symptoms appeared.

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Department of Radiology

Stanford Stroke Center

Osteoporosis: Prevention and Treatment

Posted By SHL Librarian

Presented by: Joy Wu, MD, PhD
Assistant Professor, Medicine (Endocrinology)
February 25, 2016

Most people are aware that as they age, their bones aren’t as strong as when they were young. But many don’t realize how common osteoporosis is.

“A pretty significant proportion of the American population has some degree of bone loss,” said Joy Wu, MD, PhD, at a presentation for the Stanford Health Library. “Half of all women over 50 are going to have a fracture from osteoporosis.” Men have a lower but not insignificant lifetime risk of about 20 percent, she said.

Osteoporosis is defined as having “porous bones,” with a decrease in bone mass that leads to fractures. When low bone mass is less severe, it is called osteopenia. Either condition can leave bones vulnerable to fracture.

Altogether, osteoporosis leads to about 1.5 million fractures a year in the United States. About half a million people end up in the hospital.

“That’s a lot of fractures every day in this country. And many of them are sadly preventable,” said Dr. Wu, who is an assistant professor of medicine in the division of endocrinology, gerontology and metabolism at Stanford University Medical Center.

The most frequent fractures from osteoporosis are in the spine, the wrist or hip.

—Spine fractures, which are the most common, account for more than a quarter of fractures. About half are asymptomatic. They may be found on an X-ray or an MRI. Sometimes they are identified when people realize they’ve lost 3 to 4 inches of height, which signals spinal compression fractures. The other half of spinal fractures are very symptomatic—with severe back pain.

“Somebody might be bending over a bathtub or picking something up from the floor,” Dr. Wu said. “Suddenly there’s a pop, and they feel excruciating back pain.”

—The second-most common site for osteoporosis fractures is the wrist. Typically it happens when people extend their hands to break a fall. Dr. Wu has seen many patients during winter snowstorms when they slip on ice and fall. “It’s very, very painful,” she said.

—Hip fractures are the third-most common osteoporosis fracture, and the most serious. “They are devastating,” Dr. Wu said. Hip fractures can leave people unable to walk for a long time. “Many people end up in nursing homes for a prolonged time,” Dr. Wu said. Some people never really recover.

“The number I find most shocking is, after a hip fracture, the estimates are that 20 percent to 30 percent of people will die within a year,” Dr. Wu said. “Half of people never walk again.”

The risk for hip fracture peaks late in life, at about age 75. Spine and shoulder fractures are evenly spread among ages over 50. In contrast, wrist fractures are most common in people age 50 to 60, Dr. Wu said.

Dr. Wu has come to see a wrist fracture in a 50-something woman as a warning sign the woman is more likely to get a hip fracture in her 70s—unless she gets preventive treatment.

In recent years, doctors have begun to realize that men can get osteoporosis as well. About one-third of all hip fractures occur in men, Dr. Wu said. Men getting hip fractures are twice as likely to die within a year as women, a death rate Dr. Wu called alarmingly high. “The consequences, if anything, can be even worse,” Dr. Wu said. “Some of that is because men are older when they get a hip fracture.”

For men and women, these fractures are preventable—if they get treatment. The decision to start treatment is based on whether a person has one or more of the following risk factors:

  • Age
  • Previous fracture
  • Getting glucocorticoid therapy
  • Family history of osteoporosis, fractures
  • Low body weight
  • Cigarette smoking
  • Excessive alcohol (more than two drinks/day for women, three/day for men)
  • Rheumatoid arthritis
  • Taking drugs known to increase fracture risk (including some heartburn drugs)

For each person, it’s the combination of all of these risk factors that determine if they should start treatment, Dr. Wu said. “If you’ve ever had a fracture, you’re at much higher risk for having more fractures.”

Before initiating treatment, many people get a test of their bone density, called a DXA scan. Dr. Wu recommends that women over age 65 and men over age 70 get this test. The test is also recommended for anyone over age 50 who has other risk factors, or who has had a previous fracture not due to trauma after age 50.

DXA scans typically measure bone density in the hips and spine, presenting the results as a “T score.” In general, T scores fall into these categories:

  • A score of -2.5 or lower indicates osteoporosis
  • A score of -1.0 to -2.5 indicates osteopenia (some weakening of bones)
  • A score of -1.0 or higher is normal, with 0.0 normal for age 30

T score doesn’t tell the whole story, however. The other number that tells doctors whether to recommend treatment is age.

“Your fracture risk is very much dependent on both your bone density and your age,” Dr. Wu said. Even those with normal bone density can have a higher fracture risk at an advanced age.

Using the T score and age, doctors can estimate a person’s 10-year probability of fracture, which estimates how likely it is that someone will get a fracture in the next 10 years. The threshold for starting treatment, under current medical guidelines, is a 10-year probability of hip fracture of 3 percent or higher.

That means that T scores alone don’t determine whether a doctor recommends treatment, Dr. Wu said. A woman with a -2.5 T score at age 55 is below the threshold for treatment, but the same score when she is age 65 puts her right on the edge of the threshold. A woman age 75 with the same score should be treated. Still other risk factors can also influence whether treatment is warranted.

“Bone density scan is not a crystal ball,” Dr. Wu said. Even when it’s used to estimate the probability of a fracture, that remains a probability—not a certainty. Many women get fractures even when their T scores don’t indicate osteoporosis. In fact, half of all fractures occur in women whose bones show only the milder weakness called osteopenia rather than full osteoporosis.

Drug treatment can prevent fractures by blocking the breakdown of bone, or by promoting bone formation. The first category includes the most commonly prescribed drugs, the bisphosphonates (Fosamax, Reclast, Boniva), and denosumab (Prolia); the second group includes a newer drug, teriparatide (Forteo).

Many women considering treatment for osteoporosis are concerned about safety, Dr. Wu said. A common side effect of the bisphosphonates is heartburn, which usually can be minimized. Rare side effects include atypical fractures in the thigh bone, or osteonecrosis of the jaw. Dr. Wu said studies have shown 97 percent of the jaw problems have occurred in patients getting much higher doses of bisphosphonates prescribed for cancer rather than the lower doses for osteoporosis. The benefits of treating osteoporosis for five years or less “far, far” outweigh the risks of treatment, Dr. Wu said.

Apart from treatment, people can also make changes in lifestyle to improve their bone health:

  • Be physically active to keep bones strong
  • Avoid falls at home by moving slippery throw rugs out of the way
  • Maintain a healthy weight
  • Avoid smoking
  • Limit alcohol drinking
  • Get enough calcium and vitamin D from food and/or taking supplements

To keep bones strong, most women need 1,000 to 1,200 mg. of calcium per day. Milk, yogurt, cheddar cheese and fortified orange juice are all good sources. But someone would have to drink 3 or 4 glasses of milk a day to get enough calcium—which most adults find difficult—so supplements can help meet the daily goal. For vitamin D, many people rely on supplements to get the recommended 600-800 IUs per day. Taking higher doses of vitamin D isn’t recommended because it can increase the risk for kidney stones, Dr. Wu said.

Taking these lifestyle steps can help maintain strong bones, but they may not prevent fractures in people who already have weak bones, however. “Lifestyle changes can slow—but not reverse—osteoporosis,” Dr. Wu said. “Treatment, when used properly, can be safe.”

About the speaker
Joy Wu, MD, PhD, received her medical degree from Duke University and completed her medical residency at Brigham and Women’s Hospital and her clinical fellowship in endocrinology at Massachusetts General Hospital, both at Harvard Medical School. She is board-certified in internal medicine and a member of the Endocrine Society and the American Society for Bone and Mineral Research. Her medical interests include osteoporosis, metabolic bone disease and disorders of mineral metabolism.

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What is Venous Disease Exactly?

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Presented by:  Eri Fukaya, MD, PhD
Clinical Instructor, Vascular Medicine
June 9, 2016

The basic concept of how blood moves through the body has been observed since the days of Hippocrates, but it wasn’t until the mid-1600s that early scientists realized that the blood’s circulation was based on one interconnected framework.

The network of blood vessels that delivers oxygen and nutrients to the cells is composed of three interconnected systems: The arterial system includes arteries, the thick, muscular vessels that carry blood away from the heart; the venous system, made up of veins that bring blood back to the heart; and the lymphatic system, which removes the blood’s toxins.

Within the venous system there are superficial veins, which are located just under the skin, and deep veins, located in the muscles and along the bones. Veins are not as rigid as arteries, which allow them to dilate and expand. They are able to push blood back to the heart through a series of one-way valves that work like swinging doors that close up once blood is forced through. In the legs, these valves, along with muscles in the calf that contract and relax, push the blood against gravity and back toward the heart.

“Muscle contractions in your lower legs act as pumps, and the vein’s elastic walls help blood return to the heart,” said Eri Fukaya, MD, PhD, a clinical Instructor of vascular surgery, who spoke at a presentation sponsored by the Stanford Health Library.

Reflux and Pressure Problems
Venous disease reflux occurs when these small valves no long function properly, allowing blood to flow backward toward the foot. The flexible walls of the vein balloon outward so the valves do not close properly, causing blood to accumulate and pool in the legs. As a result, the vein tends to bulge and twist, causing a spider vein or varicose vein, depending on the size and location of the vessel. If the condition worsens, the vessel walls may develop chronic inflammation and sustain high venous pressure.

Symptoms of reflux can include dull aching pain, cramps, swelling, or sensations of itching, tingling burning, or throbbing. Advanced cases can lead to skin changes or ulcers.

Occasionally, veins deep within the legs become enlarged and develop a blood clot, a condition known as thrombophlebitis or deep vein thrombosis. The condition is serious since a clot can travel to the lungs, block a major vessel, and cause a pulmonary embolism. Deep vein thrombosis can cause leg pain or swelling, but may occur without any symptoms.

The causes of venous disease are not clearly defined, though there appears to be a genetic factor. Venous disease is more common in women and in people over age 50. Valve damage may occur as the result of aging, obesity, extended sitting or standing, or reduced mobility. Pregnant women often develop varicose veins, and the condition is more prevalent in professions that require long periods of standing, such as food servers, nurses, and factory workers.

Though there is no guaranteed way to prevent venous disease, it’s important to stay active and exercise to keep calf muscles strong. Walking is the best preventive activity, Dr. Fukaya said. Keep weight down, and avoid sitting for extended periods.

Diagnosis and Treatment
Diagnosis is usually done using duplex ultrasound, a noninvasive imaging technology that shows how blood is moving through the arteries and veins. During the exam, if the normally flexible vein does not collapse when pressure is applied, it could imply the presence of a clot.

The first line of treatment for reflux is compression; support stockings create an external scaffold on the legs, reducing pressure and improving calf muscle pump function to slow the progression of venous disease and ease symptoms. Dr. Fukaya suggested starting by using compression stockings or socks at 20 to 30 mmHg (the measurement of pressure) and moving slowly to higher compression.

The history of surgery for varicose veins goes back hundreds of years, and venous disease now can be treated on an outpatient basis with minimally invasive procedures. Endovenous ablation is a catheter-based procedure that shuts down the refluxing vein. Phlebectomy removes varicose veins through a series of tiny skin punctures with small surgical hooks. An option for smaller veins and spider veins is sclerotherapy, in which a solution is injected directly into the vein, which then scars, closes up, and eventually disappears. Newer and less invasive approaches continue to be explored and developed.

“Closing off a vein or part of vein is not an issue because blood will reroute its way back to the heart,” Dr. Fukaya said. “The deeper veins take care of the larger volumes of blood.”

Deep vein thrombosis is treated with blood thinners to prevent the clot from getting bigger or breaking loose and causing a pulmonary embolism. Anticoagulants like warfarin and heparin decrease the blood’s ability to clot but need to be monitored for possible side effects, she said. Novel anticoagulant (NOAC) drugs show promise as a new option.

Clots have historically been treated surgically using clamps or filters to prevent migration but with less than perfect results. Clinical trials for newer therapies such as catheter-based thrombolysis, which target the site of a blood clot and dissolve the blockage, are being explored to minimize long-term complications of post-thrombotic syndrome.

“We still don’t know why venous disease develops, but in the future we hope that genetics will provide a tool to home in on an underlying cause,” Dr. Fukaya said.

About the Speaker

Eri Fukaya, MD, PhD, is a clinical instructor in the Division of Vascular Surgery and a specialist in diagnosing and treating venous disease. She received her MD and PhD from Tokyo Women’s Medical University and completed a fellowship in vascular medicine at the University of Pennsylvania. She did a residency in internal medicine at Lankenau Medical Center in Pennsylvania and in plastic and reconstructive surgery at Tokyo Women’s Medical University. She joined the Stanford faculty in 2015.

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Division of Vascular and Endovascular Surgery

Vascular and Vein Clinic

Vascular and Endovascular Surgery Clinic

Center for Lymphatic and Venous Disorders