Extracranial-Intracranial Bypass Surgery Using The Posterior Auricular Artery: A Report Of Three Cases

Occasionally, no branch of the superficial temporal artery (STA) is available for extracranial-to-intracranial bypass (EC-IC bypass) surgery in the territory of the middle cerebral artery (MCA). The posterior auricular artery (PAA) mainly supplies the auricle and postauricular skin. The PAA is often emphasized as the feeding artery of a pedicle skin flap in reconstruction surgery around the auricle. Only five cases have been described in three reports of PAA-MCA bypass in the literature. We report three cases of EC-IC bypass using the PAA for MCA occlusion. The parietal branch of the STA was absent in two cases, and the other branches of the STA had been sacrificed during a previous operation in one case. The PAA had become larger than usual and extended to the parietal scalp in all cases. Two patients underwent double anastomosis of the frontal branch of the STA-MCA and PAA-MCA, and one patient was treated with single anastomosis involving the PAA-MCA. We made separate question mark-shaped, linear, and Y-shaped skin incisions. The bypass remained patent in all the cases. The PAA has a complementary role to those of the STA and occipital artery in the blood supply of the parietotemporal scalp. Presumably, when the STA branch is absent or has already been sacrificed or used, the PAA occasionally extends to the parietal scalp, maintaining an adequate caliber of the vessel. We suggest that the PAA is a potential alternative to the STA as a donor artery in EC-IC bypass. Selection of the proper operative method in PAA-MCA bypass is mandatory.