The cavernous sinus is a paired trabeculated dural venous sinus on either side of the sella turcica and body of the sphenoid. The internal carotid artery and abducens nerve (CN VI) pass through the sinus, while the oculomotor (CN III), trochlear (CN IV), and the ophthalmic (V1) and maxillary (V2) divisions of the trigeminal nerve run in the lateral wall. The two sinuses are connected by the intercavernous sinuses passing anterior and posterior to the pituitary gland.
Cavernous sinus syndrome produces a combination of ophthalmoplegia, periorbital pain, and facial numbness from involvement of CN III, IV, VI, V1, and V2, with or without proptosis from venous obstruction. Causes include carotid-cavernous fistula, tumour (meningioma, pituitary adenoma, nasopharyngeal carcinoma), and septic thrombosis from periorbital or dental infections. Cavernous sinus thrombosis is a life-threatening infection requiring antibiotics and anticoagulation. The sinus is a landmark in transsphenoidal pituitary surgery where the cavernous sinus walls define the lateral limits of resection.
Abnormal communication between the cavernous internal carotid artery and the cavernous sinus, from trauma or spontaneous dural fistula, produces pulsating proptosis, chemosis, and orbital bruit with arterialization of the episcleral veins, managed by endovascular coiling or covered stent occlusion of the fistula.
Septic thrombosis from dental, sinus, or periorbital infection produces fever, proptosis, ophthalmoplegia, and periorbital oedema with bilateral involvement due to intercavernous connections; a medical emergency requiring high-dose intravenous antibiotics, anticoagulation, and drainage of any primary source.
