Sinus pericranii (SP) is a rare vascular anomaly where single or multiple transosseous veins connect extracranial veins and intracranial dural sinuses. The etiopathogenesis is unclear, but mutations in the Tie2 receptor have been found in almost 50% of patients. Thus, a family history can be an important risk factor to consider. There are 2 types of SPs: dominant and accessory. It is essential to know the type of SP when considering therapeutic intervention, as treatment recommendations vary. When the major portion of intracranial venous outflow is through SP, it is considered dominant. When only a minor portion of the venous outflow relies on the SP, it is defined as accessory.

SP typically presents at birth or in childhood as a mass on the midline frontal scalp that is nonpulsatile and that may increase in size with Valsalva maneuvers, Trendelenburg positioning, and crying. Most patients are asymptomatic, but nausea, vertigo, and headache may be associated. The headache may have sudden onset and typically waxes and wanes. 

SP may be an isolated phenomenon, or it may occur in concert with other developmental abnormalities, including craniosynostosis or dural sinus hypoplasia, or syndromes, such as Noonan syndrome and Coffin-Siris syndrome.

Rare complications of SP include hemorrhage, infection, and retrograde sinus thrombosis.