頭蓋内狭窄病変に対する抗血栓療法と脳血管内治療  [in Japanese] Antithrombotic Therapy and Endovascular Therapy for Atherosclerotic Intracranial Stenosis  [in Japanese]

Atherosclerotic intracranial stenosis is a common etiology for ischemic stroke and TIA in Japan. The natural history of intracranial stenosis is poorer than that of patients with extracranial stenosis, with annual stroke rates that approximate 5% to 15%. There are no conclusive answers about the best medical treatment of intracranial stenosis. Retrospective data suggest that long-term anticoagulation with warfarin is more effective than antiplatelet therapy. However, recent data of a randomized prospective study suggest that aspirin rather than warfarin should be used to treat intracranial stenosis, because warfarin was associated with significantly higher rates of adverse events and provided no benefit over aspirin. Patients with symptomatic intracranial stenosis who fail antithrombotic therapy appear to have a high incidence of subsequent cerebral ischemic events. The optimal treatment strategy for patients with this disease remains undetermined. Intracranial balloon angioplasty and stenting has recently been proposed as a promising treatment for patients with ongoing cerebral ischemic events despite standard medical therapy. The success rates of angioplasty alone and stent-assisted angioplasty have been reported to be approximately 85% and 95%, respectively. The complication rates of these procedures have been reported to be approximately 15%. Despite the recent advances in technology and experience, there are potential technical problems with the procedure, including dissection, vessel rupture, acute closure, elastic recoil, perforator occlusion, distal embolism, in-stent thrombosis, and hemorrhage due to hyperperfusion. Currently the efficacy of endovascular therapy versus medical therapy for patients with symptomatic intracranial stenosis has not been compared in a randomized prospective trial. Therefore, for symptomatic patients with a severe intracranial stenosis who have failed medical therapy, balloon angioplasty with or without stenting should be considered. Patients who have an asymptomatic intracranial arterial stenosis should first be counseled regarding optimizing medical therapy. There is insufficient evidence to make definitive recommendations regarding endovascular therapy in asymptomatic patients with severe intracranial atherosclerosis.