White matter-guided transtemporal corridors: An anatomical blueprint for safe access through the temporal lobe

Abstract

Background: Transtemporal approaches provide access to deep temporal and intraventricular lesions but may traverse critical white matter pathways, making tract-aware planning important for minimizing postoperative deficits. Therefore, the microsurgical anatomy of commonly used transtemporal corridors, the fibers encountered along each approach, and their tract-specific risk profiles should be defined to guide corridor selection. Methods: Three formalin-fixed cadaveric brain specimens (six hemispheres) were dissected, proceeding stepwise from the cortical surface to the ventricular system. Results: Posterior superior temporal gyrus approaches lay close to the arcuate fasciculus (AF) and superior longitudinal fasciculus, with the middle longitudinal fasciculus encountered at a deeper plane; trajectories toward the roof of the temporal horn or atrium approached the optic radiation (OR) and Meyer's loop. Middle temporal gyrus and inferior temporal sulcus corridors lay adjacent to the OR-particularly Meyer's loop-and the inferior fronto-occipital fasciculus (IFOF) within the sagittal stratum. Inferior temporal gyrus approaches remained distant from the AF and uncinate fasciculus (UF), with the inferior longitudinal fasciculus (ILF) most closely related to the trajectory, while the OR and IFOF remained superior and medial. The transsylvian corridor traversed the temporal stem near the UF and central IFOF, with superior extension toward the ventricular roof placing Meyer's loop and the OR at risk. Conclusion: Safer transtemporal surgery depends on the relationship between the surgical corridor and associated fibers, rather than the cortical entry point alone. These findings provide an anatomical framework for white matter-guided planning and tract-sparing corridor selection.