Sigmoid sinus

Sigmoid sinus is an “S” shaped blood vessel on the temporal and occipital bones. It becomes continuous in its inferior limit to the jugular vein, which is the major blood outflow tract of the head into the neck. The sigmoid sinus ends up at the transverse sinus, at the other end of the temporal bone.

The sigmoid sinus should not be injured under normal circumstances. If it is inadvertently injured, there are well established techniques for dealing with the bleeding and the outcome for the patient is usually very good.

The sigmoid sinus can however be occluded if necessary.

It is sometimes intentionally: (1)  divided, particularly when a glomus tumour is invading into the vessel.

2. compressed to gain access to the internal auditory meatus.

3. entered when there is a lateral sinus thrombosis. This vessel is involved in an inflammatory and infectious situation where the blood within it is clotted up, leading to a condition known as benign intracranial hypertension. It is sometimes the intent to open up and evacuate that clot.