PERSISTANT OCCIPITAL SINUSES

Abnormal sinuses seen originating from torcula heterophili and coursing posterolaterally.

The sinuses are joining the internal jugular veins bilaterally.

·        Occipital sinuses usually communicate cranially at the torcular Herophili and caudally at the foramen magnum, where a multitude of variations may exist.

·        Occipital sinuses have been reported in up to 10% of normal subjects and may be associated with atretic transverse/sigmoid sinus segments and internal jugular vein. Correlation with CT may bolster confident diagnosis by demonstrating a smaller caliber sigmoid sinus groove and/or jugular foramen.

·        Occipital venous network is believed to regress once most of the venous flow passes through the major dural sinuses when children assume the upright position.

·        Accidental discovery of a persistent occipital sinus during posterior fossa surgery can result in catastrophic hemorrhage and/or occlusion of the occipital sinus that may lead to venous thrombosis/infarction.