Persistent fetal superficial middle cerebral vein: an anatomical study

The superficial middle cerebral vein (SMCV) drains the venous blood from most of the superolateral surface of the brain and drains typically into the cavernous sinus as mentioned in standard textbooks. But the drainage of the SMCV is variable as indicated by various radiological studies. Although variations in the drainage of the SMCV exist, there is a shortage in the literature providing cadaveric evidence for the same. The present study was designed to identify the variations in the drainage pattern of the SMCV in fetal cadavers. During the dissection of formalin-fixed full-term fetuses, deviation in the drainage of the SMCV was observed in five out of 30 cases. In three out of 30 specimens (10%), SMCV was observed draining into superior petrosal sinus; and in two specimens (6.6%) into the transverse sinus. In the remaining specimens, the SMCV drained directly into the cavernous sinus. Knowledge of the variations noted in the present study is essential, not only for diagnosing several diseases involving the cavernous sinus or paracavernous sinuses but also in surgeries of paracavernous sinus lesions and endovascular treatment of arteriovenous fistulas. The SMCV and superior petrosal sinus can be a venous refluxing route in patients with arteriovenous fistulas.