Anterior Transsplenial Corridor to the Pineal Region: A Microsurgical and MR Venographic Study

The anterior interhemispheric transsplenial corridor, described by Yağmurlu et al. (2018), offers a supratentorial route to the pineal region and falcotentorial junction. Its premise-that few bridging veins cross the precoronal superior sagittal sinus (SSS)-has remained unquantified.

Five silicone-injected cadaveric specimens were dissected along the corridor. MR venograms of 49 adults were reviewed; the SSS was divided into ten equal sagittal zones and 317 bridging veins assigned by dural entry point. The precoronal corridor (zones 2-3) was compared with the parietooccipital corridor (zones 6-7). Galenic angles, and-in exploratory subsets-vein caliber and insertion angle, were measured.

The precoronal corridor contained 69 bridging veins (22%) versus 105 (33%) parietooccipitally-significant on aggregate binomial (p = 0.0078) and per-patient paired testing (Wilcoxon, p = 0.001). It was not vein-free: at least one precoronal vein in 92% of patients (mean 1.4 vs 2.1). Distribution was non-uniform, peaking at mid-convexity (χ² = 132.5, p < 0.0001). In exploratory subsets, precoronal veins were not of smaller caliber (difference <1 mm; p = 0.15) and met the sinus more perpendicularly (94° vs 42°; p < 0.0001). The Galen-straight sinus angle was 68° ± 14° (published: 64°), steep (>80°) in 18%; the straight sinus-transverse angle was 44° ± 12°.

MR venography indicates that the precoronal corridor carries significantly fewer bridging veins than its parietooccipital counterpart, supporting the coronal-suture landmark. Observer reliability was not assessed and cohort demographics were unavailable, so these estimates require confirmation. Fewer veins is not venous safety: the corridor is venographically favorable, not risk-free.