Intracranial vascular disease (or stenosis) is a narrowing of any arteries at the base of the skull or inside the brain, and may account for roughly 10 percent of all strokes or TIAs (transient ischemic attacks). Symptoms of intracranial vascular disease are similar to those of a TIA, and may include momentary loss of vision in one eye, weakness or numbness on one side of the body, and language problems, such as slurred speech, inability to get words out, or gibberish speech. Patients suffering from intracranial vascular disease often experience "stereotypic spells," where symptoms involving the same territory of the brain may occur in repetition. In some patients, symptoms are prompted by a drop in blood pressure, due to the effects of medication or blood loss. Intervention may be necessary for patients whose symptoms continue to recur, in spite of blood pressure and/or anemia corrections. In other patients the narrowed artery results in formation of clots that then break off to block a smaller artery downstream.
Moyamoya disease is a special type of intracranial stenosis. It is characterized by the blocking of the main arteries to the brain (usually the carotid arteries) just as they enter the skull. The brain attempts to overcome this blockage and reduction in blood flow by enlarging other smaller blood vessels in a process called forming "collaterals." In patients with moyamoya disease, the enlargement of some of the vessels at the base of the brain leads to a pattern on an angiogram that somewhat resembles a "puff of smoke." Moyamoya disease is most common in the Asian population and the term moyamoya comes from the Japanese word for "puff-of-smoke." Patients with moyamoya disease are prone to strokes and brain hemorrhages. Patients may first require medical attention as children or adults. Symptoms may also vary widely. Medical treatments are often ineffective and surgery is frequently required. The goal of surgery is to provide more blood flow to the brain in order to decrease the future risk of stroke. Several procedures or combinations of procedures may be tried. The most common include:
Intracranial vascular disease is usually diagnosed using MRI/MRA, CT/CTA or angiograms. In the past, surgery was not an easy option, since reaching the affected areas was difficult and complicated. However, in recent years new surgical techniques and minimally invasive tools are providing patients with possible treatments. Angioplasty and/or stenting can also be employed.
None of these techniques has been rigorously studied, but in select patients, these are reasonable treatment options. The controversy in treating intracranial disease is whether placing patients on blood-thinning medication is an effective means of preventing a stroke.
Traditionally, after a carotid artery is completely blocked or occluded, a patient will not continue to suffer additional strokes. However, in rare instances, a patient may continue to experience new strokes or TIAs even after their carotid artery has become completely blocked. When these strokes are caused by lack of blood flow, a procedure called an extracranial to intracranial (EC-IC) bypass may be performed. During the EC-IC bypass procedure, an artery from the scalp is connected to an artery in the brain, providing extra blood flow to the brain.