Transzygomatic-Subtemporal Approach for Middle Meningeal-to-P2 Segment of the Posterior Cerebral Artery Bypass: An Anatomical and Technical Study.

We evaluated the use of a bypass between the middle meningeal artery (MMA) and P2 segment of the posterior cerebral artery (PCA) as an alternative to an external carotid artery (ECA-to-PCA) anastomosis. Five adult cadaveric heads (10 sides) were used. After a temporal craniotomy and zygomatic arch osteotomy were performed, the dura of the floor of the middle cranial fossa was separated and elevated. The MMA was dissected away from the dura until the foramen spinosum was reached. Intradurally, the carotid and sylvian cisterns were opened. After the temporal lobe was retracted, the interpeduncular and ambient cisterns were opened and the P2 segment of the PCA was exposed. The MMA trunk was transsected just before the bifurcation of its anterior and posterior branches where it passes inside the dura and over the foramen spinosum. It was anastomosed end to side with the P2 segment of the PCA. The mean caliber of the MMA trunk before its bifurcation was 2.1 +/- 0.25 mm, and the mean caliber of the P2 was 2.2 +/- 0.2 mm. The mean length of the MMA used to perform the bypass was 32 +/- 4.1 mm, and the mean length of the MMA trunk was 39.5 +/- 4.4 mm. This bypass procedure is simpler to perform than an ECA-to-P2 revascularization using long grafts. The caliber and length of the MMA trunk are suitable to provide sufficient blood flow. Furthermore, the course of the bypass is straight.