An Overlooked Venous Sinus

The inferior intercavernous sinus is a venous connection of various sizes joining both cavernous sinuses. It lies under the sella turcica and may be damaged, but rarely, during transsphenoidal surgery. It has been previously described when enlarged, such as with cranial hypotension or cavernous sinus fistulas. Its appearance in normal subjects has been poorly described. It has been recently shown that the diameter of the inferior intercavernous sinus varies with the sphenoid sinus pneumatization. Consequently, this venous structure is visible when sphenoid sinus pneumatization is incomplete, i.e., does not extend beyond the lowest point of the sellar floor–the nadir of the sella turcica. The inferior intercavernous sinus is ideally shown on coronal T2WIs.