Venous structures at the craniocervical junction: anatomical variations evaluated by multidetector row CT

Abstract

ABSTRACT. The aim of this study was to evaluate the anatomy of and normal variations in the craniocervical junction veins. We retrospectively reviewed 50 patients who underwent contrast-enhanced CT with a multidetector scanner. Axial and reconstructed images were evaluated by two neuroradiologists with special attention being paid to the existence and size of veins and their relationships with other venous branches around the craniocervical junction. The venous structures contributing to craniocervical junction venous drainage, including the inferior petrosal sinus (IPS), transverse-sigmoid sinus, jugular vein, condylar vein, marginal sinus and suboccipital cavernous sinus were well depicted in all cases. The occipital sinus (OS) was identified in 18 cases, including 4 cases of prominent-type OS. The IPS showed variations in drainage to the jugular vein through the jugular foramen or intraosseous course of occipital bone via the petroclival fissure. In all cases, the anterior condylar veins connected the anterior condylar confluence to the marginal sinus; however, a number of cases with asymmetry and agenesis in the posterior and lateral condylar veins were seen. The posterior condylar vein connected the suboccipital cavernous sinus to the sigmoid sinus or anterior condylar confluence. The posterior condylar canal in the occipital bone showed some differences, which were accompanied by variations in the posterior condylar veins. In conclusion, there are some anatomical variations in the venous structures of the craniocervical junction; knowledge of these differences is important for the diagnosis and treatment of skull base diseases. Contrast-enhanced CT using a multidetector scanner is useful for evaluating venous structures in the craniocervical junction. Intracranial veins and venous sinuses converge to form major dural sinuses, the transverse sinus and the sigmoid sinus, which drain into extracranial veins. These major dural sinuses are connected by other venous structures at the skull base. These venous structures form complex venous networks that drain intracranial venous flow into extracranial veins at the craniocervical junction [1]. These venous structures are also known to have an important role as collateral pathways in cases of venoocclusive disease. The typical relationships between the craniocervical junction veins are shown in Figure 1. Knowledge of the anatomical relationships and variations of these veins is necessary not only for radiological diagnosis, but also when considering surgical or endovascular treatment of skull base diseases. Some investigators have previously reported the anatomy of and variations in these veins using anatomical and radiological methods with conventional angiography or contrast-enhanced MRI [2][3][4][5][6][7][8]. CT has been recognised as inadequate for evaluations of the posterior fossa owing to artefacts from bony structures; however, recent applications of multidetector row CT (MDCT) enable us to evaluate the posterior fossa with thin-sectional axial images and/o...

Anatomical characterization of the inferior petrosal sinus and adjacent cerebellopontine angle cistern for development of an endovascular transdural cerebrospinal fluid shunt

“…Tanoue et al 15 used multidetector row CT to identify the largest diameter of the minimum axis of the IPS on transverse images, at a mean of 0.99 mm and 2.04 mm on the right and left sides, respectively. Zhang et al 12 utilized multislice spiral CT and measured IPS diameter at the cranial exit to be similar bilaterally at 1.95 mm (right) and 1.96 mm (left), and at the internal jugular confluence to be significantly larger on the right (2.65 mm vs 2.36 mm).…”

A Case of Transverse Sinus Dural Arteriovenous Fistula Treated by Transvenous Embolization via the Mastoid Emissary Vein with Femoral Venous Approach

“…The PCV originates from the sigmoid-jugular junction and passes through the posterior condylar canal (PCC) of the occipital bone, flowing in the dorsal side of the suboccipital cavernous sinus (SCS) or DCV. Tanoue et al 7) examined 50 patients (100 sides) using contrast-enhanced CT and reported that the PCV could be identified on 67 sides (67%), and that there were three variations of the PCC and PCV courses: type A (75%): the PCV branches from the inferior medial area of the sigmoid sinus, and passes through the intraoccipital-bone PCC, flowing in the posterior area of the SCS; type B (21%): the PCV passes through the PCC exposed on the intracranial surface of the occipital bone; and type C (4%): the PCV branches from the anterior condylar confluence (ACC), flowing in the SCS. In the present case, the left PCV branched from the ACC, which was consistent with type C.…”

Microsurgical Anatomy of the Lateral Condylar Vein and Its Clinical Significance

“…Previous studies identified the lateral condylar vein in 64% to 79% of paracondylar areas using corrosion cast or radiological data, similar to our findings. 1,20,21 Its origin was described as the internal jugular vein by Arnautovic et al, 26 "generally found on an anastomotic branch between the anterior condylar confluence and the internal jugular vein" by San Millan Ruiz et al, 20 and the anterior condylar confluence by Trolard, 22 Takahashi et al, 21 and Tanoue et al 1 In this study, the vein has been classified based on its origin in either the anterior condylar confluence or internal jugular vein, as described in previous reports.…”

“…1 The drainage pathways of these dural sinuses form complex networks that interconnect the intraand extracranial veins at the craniocervical junction, including the vertebral venous system. In the supine position, cerebral venous drainage occurs primarily through the internal jugular veins, but the vertebral venous system is the major outflow pathway in the erect position.…”

“…5,14,15,18,19 Although the lateral condylar vein has been encountered in some skull base approaches and used for vascular access to the anterior condylar confluence, few descriptions of its morphology can be found. 1,20,21 This study examined the anatomy of this vein. FIGURE 1.…”