[Maxillary artery to middle cerebral artery anastomosis in dog-- a new experimental model (author's transl)]

End-to-side anastomosis between the maxillary artery and a branch of the middle cerebral artery was performed in the dog. The technique was devised as a new experimental model for extracranial-intracranial arterial shunt operation. The middle cerebral artery was ligated at the origin through a subtemporal small burr hole under the operating microscope in 13 dogs. Then, the shunt operation was carried out in 8 dogs 4 hours after the ligation(acute state), and in 5 dogs 3 weeks after(chronic stage). The patency of the anastomotic site was evaluated by the selective external carotid angiography 2 weeks after the shunt operation. In the acute stage of 8 dogs, 7 cases showed patency of anastomosis (88%), and in the chronic stage of 5 dogs, arteriogram revealed 4 patent anastomosis (80%). In successful cases, arteriogram showed excellent filling of the entire territory of the middle cerebral artery through the shunts (Fig. 4, 5). Various types of experimental shunt operation were attempted in our review of the literature. Among them, the anastomosis between the superficial temporal artery and a branch of the middle cerebral artery by Yasargil (1967) is rather popular and this procedure has been used by some investigators including us to investigate the effect of the extracranial-intracranial shunt on experimental acute stroke. So far as dog's experiment is concerned, the superficial temporal artery appeared to be not suitable for a donor artery, because the superficial temporal artery runs far from the middle cerebral artery and its distal part is extremely small in caliber. Therefore, the superficial temporal artery was often obstructed by compression, kinking or narrowing by surrounding tissues and by adhesion to the bone edge of the burr hole. On the other hand, the maxillary artery of the dog, which is the largest terminal branch of the external carotid artery, has plenty of blood flow and suitable size for end-to-side anastomosis to the middle cerebral artery. In addition, maxillary artery is located very close to the proximal part of the middle cerebral artery. These anatomical and spatial advantage of the maxillary artery seemed to be favorable donor artery to the middle cerebral artery and have brought hight patency rate in our series of anastomosis than that of the other previous experimental extracranial-intracranial shunts. To our knowledge, this is the first report on successful patent shunt formation after long-term occlusion of the middle cerebral artery in animals. Now, it is in our mind that progress of the study can be expected in the field of extracranial-intracranial shunt operation for cerebral infarction by this experimental procedure.