[History and Current Situation of Indirect Bypass Surgery for Moyamoya Disease].

In indirect bypass surgery for moyamoya disease(MMD) angiogenesis is induced by attaching extracranial tissues to the brain surface, and the external carotid artery system supplements hemodynamic insufficiency in the internal carotid artery system. This procedure is specific to patients with MMD. The history of this procedure includes the development of blood supply sources and ways to efficiently supply blood to various areas of the brain. The mechanism underlying the angiogenesis induced by this procedure remains unclear. Evaluation of the indications for this procedure in adult patients with ischemic MMD and elucidation of its preventive effect on hemorrhagic MMD are warranted.