Diseases And Conditions

Intracranial atherosclerotic disease

ICAD is an important cause of stroke, resulting in 10% to 20% of stroke cases in the U.S. ICAD refers to narrowing of the major arteries of the brain. It is estimated that ICAD results in 90,000 patients each year in the U.S. with stroke or TIA. When these arteries become narrowed, they may ultimately become completely blocked, impeding blood flow to critical areas of the brain. Sometimes, these arteries are not completely blocked, but are so plugged that there is not enough blood flow to the brain, resulting in a stroke.

ICAD is caused by the same processes that lead to narrowing of arteries elsewhere in the body, like the heart and legs. This narrowing of arteries is caused by high blood pressure, high cholesterol, diabetes and smoking. This narrowing is referred to as arteriosclerosis. With years of chronic stress due to the factors described above, arteries become irritated and begin to accumulate blockages, resulting in narrowing. Ultimately these narrowings are severe enough to cause symptoms due to a lack of blood flow to the organs being supplied by these arteries.

ICAD has been studied extensively in recent years and has emerged as a very serious cause of stroke. In a recently completed study, the Warfarin and Aspirin for Symptomatic Intracranial Arterial Stenosis (WASID) study, patients with ICAD were randomized to either high dosage of aspirin (1300 mg as opposed to the commonly available 325mg dose) vs. blood thinning with a drug called Warfarin. In the WASID study, patients with brain artery narrowing of greater or equal to 70% suffered a 23% risk of recurrent stroke in the first year of the study if they initially presented with stroke symptoms. If there initial presentation was a TIA (temporary neurological symptoms) their risk of stroke was 14% in the first year. The WASID study also showed that most patients with ICAD who were going to progress to a major stroke did so after only a few weeks after their presenting symptoms. In addition, women were more likely than men to progress to a serious stroke. Whether patients were treated with high dose aspirin or blood thinners, there was no difference in the risk of developing a subsequent major stroke. The study conclusions were that there is no effective medical management for the prevention of stroke in patients with ICAD. ICAD remains one of the most significant causes of severe stroke.

In 2005, the Wingspan stent and Gateway balloon angioplasty system (Boston Scientific Neurovascular) became the countries’ first FDA approved devices for the surgical treatment of ICAD. In January 2006, a Los Angeles Brain and Spine Institute physician became the first Neurointerventional surgeon to perform this procedure in California. Since its introduction, over 3,000 Wingspan stenting procedures have been performed in the U.S. Currently, a federally funded National Institutes of Health (NIH) trial is under way to study the effectiveness of the Wingspan stent vs. medical therapy for the prevention of stroke in ICAD. The Stenting Vs. Aggressive Medical Management for Preventing Recurrent Stroke in Intracranial Stenosis (SAMMPRIS) trial is expected to get underway late summer 2008, with 50 Neurointerventional surgeons in 30 centers across the country participating. Patients will be randomized to stenting with the Wingspan system and aggressive medical management vs. medical management alone. Medical management will consist of blood pressure control, control of diabetes, strict control of cholesterol and dual anti-platelet drug therapy. The Los Angeles Brain and Spine Institute is one of 3 participating centers for this trial in California.