Surgical Strategies for Incising the Tentorium in Skull Base Approaches

Introduction: Understanding the conventional and topographical anatomy of the tentorium in different surgical approaches is critical when incising the tentorial edge to expand surgical corridors while safely preserving the integrity of the surrounding neurovasculature. We describe safe stepwise techniques for incising the tentorium in skull base approaches.

Methods: Unilateral subfrontal, pterional, subtemporal, anterior and posterior transpetrosal, suboccipital, and supracerebellar approaches were performed on cadaveric specimens. The anatomy of the tentorium and its relationships with all surrounding neurovasculature was studied and safe strategies for incising the tentorium were described for each approach.

Results: In the subfrontal and pterional approaches, the anterior petroclinoid fold can be incised until the tip of the anterior clinoid, exposing the oculomotor nerve, and expanding the carotid-oculomotor widow. In the subfrontal approach, tentorial incision increases lateral exposure beyond the tentorial edge. In the subtemporal approach, the tentorium can be incised based on the target region following identification of the trochlear nerve. Anterior petrosectomy provides anterolateral exposure of the pons and the trigeminal nerve. In the posterior transpetrosal approaches, incising the tentorium from the sinodural angle anteromedially toward the tentorial edge allows for exposure of the cerebellopontine angle up to the clivus. A more limited incision perpendicular to the sinodural angle provides a direct view into the lateral mesencephalic sulcus. A transtentorial view in the extreme lateral supracerebellar approach provides a corridor to the medial temporal lobe and thalamus and improves exposure of the posterior lateral ambient cistern. In the occipital approach, transtentorial extension exposes the pineal region.

Conclusion: Incising of the tentorium can significantly expand surgical corridors but remains technically challenging given the complexity of its anatomical relationships. A thorough knowledge of the tentorium, the venous pathways within, and its superior and inferior neurovasculature relationships is necessary to safely perform a tentorial incision that provides maximum benefit.

Publication History

Article published online:
12 February 2021