Intracranial atherosclerosis is hardening of the arteries that supply the brain, causing narrowing and blockage of these vessels. It is similar to hardening of the arteries (atherosclerosis) elsewhere in the body such as the heart or legs. If a vessel becomes completely blocked or even severely narrowed, blood flow to part of the brain can be threatened and a stroke can occur.
The same risk factors that are associated with atherosclerosis elsewhere (such as in the vessels of the heart, causing heart attacks) are associated with intracranial atherosclerosis. They include diabetes, high blood pressure, high cholesterol, and smoking. Intracranial atherosclerosis has recently been recognized as a significant risk factor for ischemic stroke. Stroke rates with maximal medical therapy range from as low as 10% per year to as high as 30% per month, making intracranial atherosclerosis about four to five times more dangerous than an unruptured aneurysm or AVM. Unfortunately, unlike atherosclerosis of the arteries leading to the brain (carotid arteries), which often causes transient ischemic attacks (TIAs or ministrokes), intracranial atherosclerosis often is only found when a major stroke occurs.
Unlike atherosclerosis of the arteries leading to the brain (carotid and vertebral arteries), which often causes transient ischemic attacks (TIAs or ministrokes), intracranial atherosclerosis often is first found when a major stroke occurs. For this reason, it is important to treat intracranial atherosclerosis when it is found. This is accomplished by inserting a catheter into the groin and threading it up through the vessels to the site of the plaque. First, a balloon is deployed and expanded within the narrowing, pushing the plaque back against the artery walls (similar to angioplasty in the heart). As in the heart, stents may then be implanted to cover the plaque and keep the vessel open.
Although medical treatment may help decrease the chance of a stroke, it is not as effective as medical treatment for carotid artery disease. However, this form of treatment is becoming more common.