Tentorial venous anatomy: Variation in the healthy population

BACKGROUND AND PURPOSE: A new transtentorial venous system consisting of medial, intermediate, and lateral tentorial veins, connecting infra- and supratentorial compartments, was recently shown in 2 cadaver dissections and 2 patient scans. We sought to characterize the venous patterns within the tentorium and their relation to measures of skull development in a cohort of healthy adults. MATERIALS AND METHODS: We retrospectively reviewed tentorial venous anatomy of the head using CTA/CTV performed for routine care or research purposes in 238 patients. Included studies had adequate contrast opacification of venous structures and a section thickness of #2 mm; we excluded cases with space-occupying lesions and vascular pathologies. Tentorial angle, dural sinus configurations, and measures of skull base development were assessed as predictors of tentorial venous anatomy variation via Cramér V association, the binary encoded Pearson correlation, and nearest-point algorithm with the Euclidean distance metric for clustering. RESULTS: Tentorial vein development was related to the ringed configuration of the tentorial sinuses (P,.005). There were 3 configurations. Groups 1A and 1B (n ¼ 50/238) had ringed configuration, while group 2 did not (n ¼ 188/238). Group 1A (n ¼ 38/50) had a medialized ringed configuration, and group 1B had a lateralized ringed configuration (n ¼ 12/50). Measurements of skull base development were predictive of these groups. The ringed configuration of group 1 was related to the presence of a split confluens, which correlated with a decreased internal auditory canal-petroclival fissure angle. Configuration 1A was related to the degree of petrous apex pneumatization (P value ¼.010). CONCLUSIONS: Variations in the transtentorial venous system directly correlate with cranial development.