Straight sinus: ultrastructural analysis aimed at surgical tumor resection

Abstract

OBJECTIVE Accurate knowledge of the anatomy of the straight sinus (SS) is relevant for surgical purposes. During one surgical procedure involving the removal of part of the SS wall, the authors observed that the venous blood flow was maintained in the SS, possibly through a vein-like structure within the dural sinus or dural multiple layers. This observation and its divergence from descriptions of the histological features of the SS walls motivated the present study. The authors aimed to investigate whether it is possible to dissect the SS walls while keeping the lumen intact, and to describe the histological and ultrastructural composition of the SS wall. METHODS A total of 22 cadaveric specimens were used. The SS was divided into three portions: anterior, middle, and posterior. The characteristics of the SS walls were analyzed, and the feasibility of dissecting them while keeping the SS lumen intact was assessed. The thickness and the number of collagen fibers and other tissues in the SS walls were compared with the same variables in other venous sinuses. Masson's trichrome and Verhoeff's stains were used to assess collagen and elastic fibers, respectively. The data were analyzed using Zeiss image analysis software (KS400). RESULTS A vein-like structure independent of the SS walls was found in at least one of the portions of the SS in 8 of 22 samples (36.36%). The inferior wall could be delaminated in at least one portion in 21 of 22 samples (95.45%), whereas the lateral walls could seldom be delaminated. The inferior wall of the SS was thicker (p < 0.05) and exhibited less collagen and greater amounts of other tissues—including elastic fibers, connective tissue, blood vessels, and nerve fibers (p < 0.05)—compared with the lateral walls. Transmission electron microscopy revealed the presence of muscle fibers at a level deeper than that of the subendothelial connective tissue in the inferior wall of the SS, extending from its junction with the great cerebral vein to the confluence of sinuses. CONCLUSIONS The presence of a structure within the SS that can maintain the venous blood flow despite the dural wall might be considered an anatomical variation. The greater thickness of the inferior wall of the SS compared with the lateral walls is mainly due to the presence of larger amounts of tissues other than collagen. Delamination of the inferior wall of the SS was mostly possible in its inferior wall, but an attempt to delaminate the lateral walls is not recommended. Ultrastructural assessment corroborated a recent report of the presence of muscle fibers in the inferior wall of the SS.

Visualization of the tentorial innervation of human dura mater

“…; Amato et al. ). The Carnegie Collections indicate that at stage 13 of embryo development (when the embryo has a size of 4–6 mm), the ophthalmic division is the clearest of the tripartite divisions of the trigeminal ganglion, and both mesenchymal and neural crest‐derived cells appear to be involved in the formation of the primary meninges (O'Rahilly & Müller, ; Tanaka, ).…”

“…; Tanaka, ; Amato et al. ; Shibao et al. ), and so the present study investigated the straight and transverse sinuses adjacent to the tentorium cerebelli in order to elucidate the course of the nervus tentorii.…”

“…As the brain hemispheres increase in size, the dural mesenchymal tissue of floating parts such as the tentorium cerebelli and falx cerebri become fused and compressed at an earlier stage compared with the dural membrane of the bony structure (Tanaka, ; Amato et al. ). Furthermore, the density of dural innervation decreases due to axon traction, apoptosis of the trigeminal ganglion cells, and changes in neuropeptide expression in trigeminal ganglion cells, mostly during post‐natal days 5–55 (Davidson et al.…”

“…Previous descriptions of the supratentorial innervation have been crude and inconsistent, including the medical illustrations that appear in both textbooks and journal articles (Drake et al 2009;Gilroy et al 2009;Moore et al 2009;Kemp et al 2012;Bauer et al 2005). Accurate knowledge of the anatomy of the venous sinuses in the dura mater is important during neurosurgery involving the arteriovenous fistula or when resecting meningiomas and other types of brain tumours (Tubbs et al 2007;Tatarli et al 2013;Xu et al 2013;Tanaka, 2015;Amato et al 2016;Shibao et al 2016), and so the present study investigated the straight and transverse sinuses adjacent to the tentorium cerebelli in order to elucidate the course of the nervus tentorii.…”

“…3, arrows). Diverse patterns of supratentorial innervation might result from variations in the dynamics of the cranial dura mater and trigeminal ganglion during the early stage of embryo development (O' Rahilly & M€ uller, 2007;Davidson et al 2012;Amato et al 2016). The Carnegie Collections indicate that at stage 13 of embryo development (when the embryo has a size of 4-6 mm), the ophthalmic division is the clearest of the tripartite divisions of the trigeminal ganglion, and both mesenchymal and neural crest-derived cells appear to be involved in the formation of the primary meninges (O'Rahilly & M€ uller, 2007;Tanaka, 2015).…”