Granular Foveolae in the Groove of the Sigmoid Sinus: An Anatomical Study

Abstract

BackgroundGranular foveolae in the groove of the sigmoid sinus have rarely been reported in the literature compared to numerous published reports on the granular foveolae near the superior sagittal sinus and its sulcus on the internal aspect of the calvaria. The present study was performed to better elucidate their prevalence and locations. Materials and methodsOne hundred and ten adult dry skulls (220 sides) were analyzed for the presence of granular foveolae within the groove of the sigmoid sinus. The exact position of the foveolae was documented, and the diameter of the granular foveola was measured. ResultsGranular foveolae were found in the groove of the sigmoid sinus on 3.6% of the sides. These were at or within a mean of 1.3 cm inferior to the transverse-sigmoid junction. When a mastoid foramen was noted in the groove, it was always located inferior to the granular foveolae when present. The mean diameters of the granular foveolae of the left groove of the sigmoid sinus were 2.8 mm and 4 mm for the right grooves. The mean depth of the granular foveolae in the left groove of the sigmoid sinus was 2.7 mm and 3.5 mm for the right grooves. Granular foveolae were statistically larger and deeper on the right versus left sides (p<0.05). ConclusionsGranular foveolae of the groove of the sigmoid sinus were identified most commonly on the right sides and 3.6% on all sides. If identified on medical imaging, these uncommon structures at the skull base should be considered normal anatomical variations.

Twenty Intracranial Skull Base Variations in the Same Specimen

“…A granular foveola along the midline of the superior sagittal sinus groove is common. However, such depressions due to large arachnoid granulations are uncommon along the sulci for the transverse and sigmoid sinuses [28].…”

Angulation of the dural venous sinuses of the posterior cranial fossa: Anatomical study with clinical and surgical applications

“…Regarding the etiological causes of CVST, several well-known general risk factors such as oral contraceptive use, pregnancy, infections, malignancy, and hypercoagulable states have been documented (Bezerra et al, 2022;Duman et al, 2017;Ferro et al, 2021Ferro et al, , 2004Jianu et al, 2018;Zhou et al, 2022Zhou et al, , 2023. Furthermore, other structural factors such as intraluminal bands, intraluminal arachnoid granulations, TS stenosis, absent TS, and extraluminal tumors have been discussed as causes of venographic filling defects and venous flow abnormalities, and are probably implicated in the mechanisms of development of diseases affecting the DVSs such as CVST (Altafulla et al, 2020;Guduri et al, 2023;Iwanaga et al, 2020;Strydom et al, 2010). Although it is a multifactorial condition, some studies report the etiology of CVST as idiopathic in up to 43%-44% of cases, and the reason for a higher predilection to TS thrombosis is unknown (Bezerra et al, 2022;Duman et al, 2017;Ferro et al, 2004).…”