The Tentorial Triangles: A Novel Concept of Tentorial Segmentation for Surgical Guidance Using the Supracerebellar Transtentorial Route.

Abstract

Despite the routine use of intraoperative navigation, a meticulous understanding of microanatomical landmarks remains crucial for neurosurgical guidance. Based on a novel concept of tentorial segmentation, cadaveric validation, and clinical application, this study aims to define potential landmarks for surgical guidance in supratentorial lesions through the supracerebellar transtentorial route. Magnetic resonance imaging-based segmentations and 3D reconstructions (n = 28) of the falco-tentorial complex and adjacent anatomical and functional structures were performed and analyzed. The anatomical findings were correlated and verified through a cadaver study (n = 7). The redefined transtentorial corridors were then individually applied in a surgical series involving patients with supratentorial lesions (n = 7). Using 2 previously undescribed anatomical lines, the tentorium was divided into distinct sections. A consistently visible and reproducible line serves as the inflection line separating the horizontal from the ascending portion of the tentorium. The angle between the laterally located horizontal and the medially located ascending portions was consistently identifiable, visible, and reproducible in magnetic resonance imaging studies, cadaver dissections, and surgical procedures. Based on additional microanatomical landmarks, 2 anteriorly located triangles-the medial tentorial triangle and lateral tentorial triangle-were defined as safe pathways for accessing supratentorial lesions without compromising functional structures. This is the first study to describe previously undescribed anatomical landmarks of the tentorium for potential surgical orientation and guidance. The tentorial triangles defined herein could provide additional entry corridors to reach lesions in the mediobasal temporal region, atrium of the lateral ventricle, and upper brainstem and thalamus, as demonstrated through successful clinical applications.