Emissary veins and foramina: topography, incidence, and clinical significance

Abstract

Emissary veins are valveless veins which pass through skull foramina connecting the intracranial dural venous sinuses to the extracranial veins. They equalize the venous pressure on both sides of the cranium, cool the brain, and may transmit extracranial infection to intracranial structures. Parietal, mastoid, sphenoidal and occipital emissary foramina and veins proved to be of great clinical significance. Petro-squamosal sinus and mastoid emissary vein may cause excessive bleeding during skull base and middle ear surgeries. Venous anomalies of some emissary veins could be a rare cause of tinnitus. Their incidence, morphology and course must be determined preoperatively to avoid interventional complications.