What is intracranial stenosis?
Intracranial stenosis is the medical term for severe narrowing of a cerebral artery that restricts blood flow to areas of the brain. This narrowing is caused by atherosclerosis. Intracranial stenosis is responsible for about 10 percent of strokes annually, and the rate of recurrent strokes without treatment can be alarmingly high.
How is intracranial stenosis diagnosed?
- Computed tomography (CT) angiography
- Magnetic resonance (MR) angiography
- Catheter-based angiography
Typical areas of intracranial stenosis include the internal carotid artery, middle cerebral artery, vertebral artery and basilar artery. Other diagnostic tests can evaluate the adequacy of blood flow to the brain.
How is intracranial stenosis treated?
Current medical treatment includes antiplatelet or anticoagulation medications such as aspirin or warfarin, anticholesterol agents, control of hypertension, and aggressive control of blood glucose in patients with diabetes.
When patients fail medical therapy, neurosurgical and neuroendovascular interventions may be indicated. Surgical treatment can include bypass grafting to increase blood flow to the brain distal to the stenosis. Typically, a superficial temporal artery-to-middle cerebral artery (STA-MCA) bypass is used. Less commonly, when the demand for blood flow is high, a high-flow bypass is placed using a large caliber vein or artery for the graft. When the arterial recipients for a direct anastomotic bypass are poor with a moyamoya-like pattern, an onlay procedure known as encephaloduroarteriosynangiosis (EDAS) or encephaloduroarteriomyosyangiosis (EDAMS) is indicated. The Barrow Neurological Institute is participating in the Carotid Occlusion Surgery Study, a multicenter prospective analysis of STA-to-MCA bypass for the treatment of patients with symptomatic occlusion of the ipsilateral internal carotid artery.
Endovascular treatments include balloon angioplasty of the stenotic artery, with or without placement of an endoluminal stent. A prospective study evaluating the effectiveness of percutaneous transluminal angioplasty and stenting for intracranial stenosis is also underway at Barrow Neurological Institute.