Importance of Anatomical Asymmetries of Transverse Sinuses: An MR Venographic Study

Abstract

Time-of-flight (TOF) magnetic resonance venography (MRV) is often used to examine the intracranial dural sinuses, particularly in the evaluation of dural sinus thrombosis. The goal of the study was to evaluate the use of TOF MRV in assessing the normal anatomy of dural sinuses and their variations as sources of potential pitfalls in the diagnosis of venous sinus thrombosis. Cerebral TOF MRV obtained in 105 persons with normal MR studies were reviewed to determine the presence, aplasia and hypoplasia of the transverse sinuses. Twenty-one (20%) aplasias of the left sinus, 41 (39%) hypoplasia of the left sinus, 33 (31%) symmetric, 6 (6%) hypoplasia of the right sinus, and 4 (4%) aplasias of the right sinus cases were determined in the asymmetry in sizes of transverse sinuses. These results suggested that transverse sinus flow gaps or aplasias can be observed in approximately 24% of normal population on MR imaging. The rate of these gaps in normal subjects must be kept in mind because it can be a source of misdiagnosis in cases of suspected dural sinus thrombosis.

The relationship between jugular foramen asymmetry and superior sagittal venous sinus laterality

“…Previous examinations of venous asymmetry have shown the right transverse sinus to be larger in 59% of cases (Ayanzen et al, 2000), and the left transverse sinus to be aplastic or hypoplastic in 59% of cases (Alper et al, 2004)this is congruent with our finding of 54.6% of skulls having a correlation between right-sided SSVS and a larger JF on the right. Significant differences were also observed in the frequency of right SSVS-JF skulls, with Otago skulls having more of this combination than Coimbra.…”

“…The majority of forebrain superficial veins drain into the SSVS (Beards et al, 1998;Brockman et al, 2012); it is located in the sagittal plane at the superior border of the falx cerebri running anterior to posterior from the crista galli of ethmoid bone to termination in the transverse sinus ( Figure 3). The SSVS is described as terminating in (draining into) the right transverse sinus in the majority of individuals (Browning, 1953;Ayanzen et al, 2000;Alper et al, 2004); the transverse sinus then passes anterolaterally to become the sigmoid sinus, then turning medially and passing anteriorly to enter the JF and become the internal jugular vein.…”

“…Interestingly, the transverse sinuses are often of unequal size and sometimes one is absent (Beards et al, 1998;Ayanzen et al, 2000;Alper et al, 2004). It has also been noted that the transverse sinus with the more direct connection to the SSVS is larger (Mas et al, 1990); it is therefore plausible that the higher volume of cerebral venous drainage via SSVS connection to a larger transverse sinus may consequently necessitate a larger JF on the ipsilateral side.…”

Variations in the cerebral venous anatomy and pitfalls in the diagnosis of cerebral venous sinus thrombosis: Low field MR experience

“…Alper et al, [12] described flow gaps in 24% of normal population. Our study revealed flow gaps [ Table 1] more at the sigmoid transverse junctions or in the lateral most aspect of the transverse sinus and to a lesser extent in the sigmoid sinus.…”

“…Alper et al, [12] described about transverse sinus abnormalities -20% aplasia and 39% hypoplasia of the left sinus, 6% hypoplasia and 4% aplasia of the right sinus and 31% symmetric sinuses. Our results also show most of the hypoplastic and aplastic transverse sinuses were on the left side only.…”