[Successfully performed STA-MCA anastomosis using a branch of the STA scarcely visible on cerebral angiography in two patients with ischemic type moyamoya disease].

Preparation of a scalp artery as a donor is the first step in the procedure of direct anastomosis for the treatment of ischemic type moyamoya disease. In some cases, the scalp artery is not visualized well on cerebral angiograms. Another scalp artery must be used as a donor or it is interposed between the proximal portion of the firstly selected scalp artery and a branch of the middle cerebral artery in that condition. Skin incision should be planned to include multiple scalp arteries. On cerebral angiograms, in the present two cases, the diameter and length of branches of the STA was thought to be too small and short to anastomose, but direct anastomosis was successfully performed with a single STA branch. In conclusion, skin flap should include multiple scalp arteries prepared for interposition, and each branch of the scalp arteries should be carefully inspected intraoperatively to determine whether an angiographically small and short branch of the scalp can be used to anastomose.