Analysis of the superficial middle cerebral vein in sphenoid ridge meningioma using contrast-enhanced dynamic computed tomography angiography

•Sphenoid ridge meningioma (SRM) effects the hemodynamics of intracranial veins.•The superficial middle cerebral vein (SMCV) changes its form and flow due to SRM.•The SMCV sometimes loses the connection to its origin such as the cavernous sinus.•The SMCV can maintain the anterograde flow partially or entirely in such a condition.•Damaging such a SMCV during surgery may cause venous complications. The superficial middle cerebral vein (SMCV) is of clinical importance because of its contribution to the venous drainage of the superficial part of the cerebrum. Sphenoid ridge meningioma (SRM) grows adjacent to the SMCV and its drainage routes, and is thought to occasionally influence the hemodynamics of the SMCV, although this has seldom been suggested in the literature. We investigated the effect of SRM on the SMCV via blood flow analysis using multi-detector computed tomography. Overall, 22 patients with SRM who preoperatively underwent contrast-enhanced dynamic computed tomography at our institution were included in this study. We serially measured the Hounsfield units at each point of the SMCV and its adjacent veins on the side on which the tumor was located. We then obtained a time-density curve for each point via gamma distribution fitting. We determined the time-to-peak at each point by calculating the derivative of the time-density curve function and deduced the direction of blood passing through each vein by comparing the time-to-peak values between several points. In total, 26 SMCVs were measured in 19 out of 22 cases. Of the 26 SMCVs, 16 were patent in the medial portion and contributed to normal venous drainage: 4 of them emptied into the cavernous sinus (CS), and 12 of them into the para-cavernous sinus (ParaCS). Out of the 10 that had their medial portions occluded because of the effects of the tumor, 6 SMCVs mainly drained into the vein of Labbé and/or the vein of Trolard retrogradely. However, in 2 of these, the small medial portions of the SMCVs near the occluded portion were maintained anterogradely by the collateral venous structures. In 4 SMCVs, the blood flow through the collateral veins remained anterograde; this was considered to contribute to normal venous drainage. The SRM is likely to cause occlusion or stenosis in the SMCV and influence its hemodynamics. In cases in which the connection between the SMCV and the CS or the ParaCS has been lost, the SMCV may still be involved in normal venous drainage via the collateral veins in some of t