The Tentorial Bridge to Deep Skull Base Exposure: Anatomic Morphometric Study.

BACKGROUND: Skull base surgeons split the tentorium to expand exposure, minimize brain retraction, and combine the supratentorial and infratentorial compartments for resection of large skull base lesions. The aim of this study was to describe stepwise techniques for splitting the tentorium to access deeply located skull base lesions and morphometrically assess gained exposure.

METHODS: Surgical exposures were performed through transsylvian, subtemporal, posterior transpetrosal, and combined posterior supratentorial/infratentorial-transsinus approaches. A custom software program was used to trace the surgical exposure region of interest for area analysis with the ability to accurately assess most irregular areas. Qualitative morphometric assessment was done of the gain in anatomic exposure achieved by splitting the tentorium.

RESULTS: In the transsylvian transtentorial approach, mean surface area increased 154.17%, from 0.14 cm2 before expansion to 0.32 cm2 after expansion. In the subtemporal transtentorial approach, mean surface area increased 137.61%, from 0.66 cm2 before expansion to 1.52 cm2 after expansion. In the posterior transpetrosal transtentorial approach, mean surface area increased 171.06%, from 1.08 cm2 before expansion to 2.81 cm2 after expansion. In the combined supratentorial/infratentorial-transsinus approach, mean surface area increased 222.03%, from 0.78 cm2 before expansion to 2.38 cm2 after expansion.

CONCLUSIONS: With splitting of the tentorium, a substantial area of expansion is obtained, minimizing the need for brain retraction and improving visualization of deep neurovascular structures in the skull base.