Neurovascular DiseaseNew Options for Neurovascular Disease
Brian-Fred Fitzsimmons, MD
Froedtert & Medical College of Wisconsin Neurologist/Neuro-interventionalist
Neurovascular disease is the number one cause of adult disability. More than four million Americans have survived a stroke, and few will recover completely. Statistics show that four out of five families, at some time, will be affected by stroke. But new technology is helping physicians minimize the impact of neurovascular disease.
Q. What is neurovascular disease?
Neurovascular disease encompasses any abnormality of the blood vessels within or supplying the brain and spine. This includes narrowing of arteries, which reduces blood flow to the brain and increases the risk of stroke (particularly “ischemic” stroke), and weakening of arteries, which may create brain aneurysms and increases the risk of intracranial bleeding (or “hemorrhagic” stroke.)
Q. Are there signs and symptoms I should be aware of regarding neurovascular disease?
Frequently, people having a stroke will have the sudden onset of weakness or numbness on one side of their body. They may also have difficulty speaking or seeing, or feel a loss of balance or coordination. Sometimes people will have only mild or brief symptoms that will completely resolve. For example, they may feel weak or clumsy in one hand, but then it completely goes away after several minutes. Or they may suddenly lose vision in one eye, but after a short time it completely returns to normal. They may ignore it or think it’s nothing, but it’s a warning sign. That’s a TIA, or transient ischemic attack, and it’s a warning that they are at risk for a large stroke in the future.
Q. What are neurovascular stents used for?
Stents are used to treat ischemic neurovascular disease. We use them to treat arteries that have narrowed within the neck or the brain, usually because of atherosclerosis (“hardening of the arteries”) associated with high blood pressure, high cholesterol, smoking or diabetes. Narrowing in these arteries can significantly limit the blood flow to the brain, increasing the risk of stroke. Stents restore the arteries to normal size, thereby reducing the risk of stroke.
Q. What’s the difference between a neurovascular stent and a stent used for the heart; aren’t they the same?
The new stent that has been developed specifically for use in the brain is called the Wingspan stent, and it’s much more flexible than a stent used in the heart. The brain arteries are much more tortuous than arteries of the heart, so we need a stent with greater flexibility to successfully navigate the brain arteries. The other main difference is that the Wingspan stent is self-expanding. When we release it, it gently opens up on its own to the desired vessel diameter. Stents used in the heart are almost exclusively balloon-mounted, which means a balloon is used to stretch the stent open. But brain arteries are much more delicate, so it’s safer to use a self-expanding stent.
Q: How does it work?
First, we approach the narrowed artery with a catheter placed through an artery in the leg and brought up into an artery in the neck under X-ray guidance. Through this catheter, we introduce a smaller catheter, about the size of a thread, which we bring all the way up to the narrowed artery within the brain. A very small balloon that has been made specifically for the brain is then advanced into the narrowed segment and slowly inflated so that it begins to partially open up the artery. We then remove the balloon and deploy the Wingspan stent, which opens up and restores the normal diameter of the vessel in a minimally traumatic fashion.
Q: What are the outcomes?
The results that we’ve seen so far have been very encouraging. Recent studies demonstrate a 97 percent chance of successfully opening a narrowed brain artery with the Wingspan stent. People with severely narrowed brain arteries who have already had a stroke or TIA have about a 20 percent chance of having another stroke within the next year, if the narrowed artery is not opened. The risk of having a stroke during the stenting procedure is about 5 percent to 6 percent, so we generally think that risk is worth taking for these patients. The ongoing question is whether stenting will significantly reduce the long-term risk of stroke. Everything we’ve gathered so far suggests that it will.
In the past, there was no treatment for these arteries at all, except for blood thinners, like aspirin or Coumadin, with the hope that by thinning out the blood, the risk of future stroke could be reduced. Unfortunately, we’ve found through multiple, very large clinical trials, that the use of medications in this situation isn’t very effective. People still have a very significant risk of future stroke, particularly if they have arteries that are narrowed more than 70 percent. So we’ve been looking for an alternative treatment that will be better, safer and much more effective. Therefore, the development of the Wingspan stent has been a real revolution in the field.
Q: Are there other options for neurovascular treatment?
Stenting can also be used to open narrowed arteries in the neck supplying blood to the brain. Stenting of the carotid artery has been around longer than stenting of brain arteries and has become a very popular alternative for patients with carotid disease.
In the past, patients with narrowed carotid arteries were treated with an open surgery called carotid endarterectomy. Now we have evidence that in patients who are high-risk for surgery (including older patients, or those with heart or lung disease who might not tolerate general anesthesia), we can successfully open their arteries with a balloon and a stent, and we can do that with mild sedation only; we don’t have to use general anesthesia, and these patients can go home the next day. Clinical evidence has proven that this procedure is safer, better tolerated, and equally efficacious for patients who are high risk for open surgery.
Hemorrhagic neurovascular diseases, such as cerebral aneurysms that predispose people to bleeding within the brain, can also be successfully treated with either endovascular coiling or microsurgical clipping
Aneurysms are like small balloons that stretch off the side of a blood vessel and can rupture. Microsurgical clipping is an effective treatment that has been around for several decades. Under general anesthesia, an incision is made in the scalp and the aneurysm is found. Then a metallic clip is placed across the aneurysm to exclude it from the rest of the circulation, so that it can never bleed.
The newer treatment, endovascular coiling, has only been routinely offered within the last ten years. Using a catheter placed through an artery in the leg and advanced into the brain under X-ray guidance, soft platinum coils are placed within the aneurysm, so that instead of a big, pulsatile balloon filled with blood, it becomes a hard sac filled with metal. Blood no longer gets into it, so it can no longer bleed, and over time the aneurysm heals around the coils and is excluded from the circulation. This procedure is also done under general anesthesia because it can take several hours and people need to be very still during the procedure for their own safety. However, the procedure is very well-tolerated, and if it’s an unruptured aneurysm, people can often go home the next day.
Q: Are these options readily available anywhere?
No. Neurovascular procedures like these are generally only performed at large, tertiary care centers, particularly academic medical centers where there are specialists who have the experience and expertise to perform these procedures safely and successfully.
Q: What does the future look like for neurovascular medicine?
This is a very, very exciting time for the field of neurovascular medicine. The technology is really growing and expanding by leaps and bounds. Almost every year, it seems, there’s a new group of patients and a new group of diseases that we can treat more effectively and more safely. I think treatment options are just going to continue to expand, particularly for patients who are having or are at risk for or are experiencing a stroke.