Anatomical variants of the emissary veins: unilateral aplasia of both the sigmoid sinus and the internal jugular vein and development of the petrosquamosal sinus. A rare case report.

We report a case of hypoplasia of the right transverse sinus and aplasia of the ipsilateral sigmoid sinus and the internal jugular vein. In addition, development of the petrosquamosal sinus and the presence of a large middle meningeal sinus and sinus communicans were observed. A 53-year-old Caucasian woman was referred for magnetic resonance imaging (MRI) investigation due to chronic headache. On the MRI scan a solitary meningioma was observed. Finally MR 2D venography revealed this extremely rare variant.