The cavernous sinus is a centrally located cavity situated at the base of the brain next to the temporal bone and sphenoid bone. Its Latin name is sinus cavernosus. This cavity contains the internal carotid artery and several important nerves including the oculomotor nerve, the trochlear nerve, the ophthalmic nerve, the maxillary nerve, and the abducens nerve. The internal carotid artery and abducens nerve run horizontally through the cavernous sinus while the remaining nerves run vertically. There are two of these sinuses, one for each hemisphere of the brain. The pituitary gland sits between the two.
The anatomy of the cavernous sinus is unique because it is the only place in the human body where an artery moves entirely through a venous structure. In this case, the internal carotid artery moves blood from the brain and face back to the heart to be oxygenated.
Health problems associated with this specific sinus include cavernous sinus thrombosis, a blood clot in the sinus. Thrombosis usually occurs after an external facial injury has lead to a clot in the facial vein. Sometimes pieces of the clot can enter the sinus and cause an infection. Infections in the eyes, ears, nose, throat, or sinuses may also spread to the sinus and cause thrombosis. Common symptoms of cavernous sinus thrombosis are bulging eyeballs, a drooping eyelid, the inability to move the eye in a particular direction, or vision loss. This type of thrombosis is rarely fatal and can be treated with antibiotics. The illness can become more serious, however, if it is left untreated and spreads to the dural veinous sinuses.
Other serious health problems related to this part of the sinus may include the growth of tumors in the sinus cavities or on the pituitary gland. Both situations can cause compression of the nerves in the sinus and lead to sensory damage, especially vision loss. Most tumors found in this region are treatable, although to varying degrees depending on the specific type of tumor. Aneurysms and fistulas can also cause damage to the sinus, and like tumors and thrombosis, lead to cavernous sinus syndrome. Cavernous sinus syndrome is a broad category of pathology that is often difficult to diagnose or define but can encompass damage to the ocular nerves and/or the pupil, bloodshot conjunctiva, a reddening in parts of the face, changes in facial sweating, and other symptoms associated with Horner’s Syndrome.