Anatomical study of subtemporal anterior transpetrosal approach

Objective To determine the anatomical features of subtemporal anterior transpetrosal (Kawase) approach. Methods Ten adult cadaveric heads were used for microsurgical dissection and measurement. Results After petrosectomy, the horizontal portion and internal auditory of the carotid artery canal was exposed, and the basal turn of cochlea between the carotid artery and canal was skeletonized. The size of the windows in the superior and medial surfaces of petrous bone averaged 2.6 cm2 and 1.9 cm2, respectively. In contrast with the subtemporal transtentorial approach, the additional exposure obtained in Kawase approach extended interiorly to the upper petroclival region, in which the vertebrabasilar and pontomedullary junction could be visualized. The arterial supply to dura in the exposed upper petroclival region mainly arose from meningohypophyseal trunk and ascending pharyngeal artery. Conclusion The Kawase approach can provide access to both the middle and posterior cranial fossa, and the exposed area of the posterior cranial fossa is limited to the upper half of the petroclival region.