Why should we report posterior fossa emissary veins?

Posterior fossa emissary veins are valveless veins that pass through cranial apertures. They participate in extracranial venous drainage of the posterior fossa dural sinuses. The mastoid emissary vein, condylar veins, occipital emissary vein, and petrosquamosal sinus are the major posterior fossa emissary veins. We believe that posterior fossa emissary veins can be detected by radiologists before surgery with a thorough understanding of their anatomy. Describing them using temporal bone computed tomography (CT), CT angiography, and cerebral magnetic resonance (MR) venography examinations results in more detailed and accurate preoperative radiological interpretation and has clinical importance. This pictorial essay reviews the anatomy of the major and clinically relevant posterior fossa emissary veins using high-resolution CT, CT angiography, and MR venography images and discusses the clinical importance of reporting these vascular variants.