The Safety of Kawase Triangle as an Anatomical Landmark for Anterior Petrosectomy in Petroclival Meningiomas

Objective: Anterior petrosectomy through the middle fossa is a well-described option for addressing cranial base lesions of the petroclival region. To access posterior fossa through middle fossa we evaluate quantitatively the safety of Kawase triangle as an anatomical landmark. Methods: We reviewed pre- and postoperative CT scans of patients with petroclival meningioma between January, 2009 and September, 2013 in which anterior petrosectomy were performed to access the posterior fossa part of the tumor. The distances between drilling start edge and drilling finish edge to the vital anatomical skull base structures such as internal carotid artery (IAC) and superior semicircular and petrous apex also drilling entrance length in coronal and axial views were measured and analyzed. Results: Drilling entrance length is directly related with tumor size. The distances between anatomical structures and drilling points decrease with increasing tumor size but always a safe margin remains between drilling points and internal auditory canal, internal carotid artery and semicircular canals in axial and coronal views. Conclusion: Kawase triangle is a safe anatomical landmark for anterior petrosectomy. Staying in such triangle avoid damages to the vital anatomical structures while accessing posterior fossa via middle fossa.