The torcular Herophili (confluence of sinuses) is the posterior cranial confluence where the superior sagittal sinus, the straight sinus, and both transverse sinuses meet at the internal occipital protuberance. In the majority of individuals the confluence is asymmetric, with the right transverse sinus receiving dominant flow from the SSS and the left receiving dominant flow from the straight sinus, though this varies considerably. The occipital sinus sometimes empties into the torcular.
The torcular is the primary venous landmark in posterior fossa surgery: suboccipital craniotomy must avoid the torcular and its adjacent transverse sinuses. Posterior falcine and occipital craniotomies border the torcular. Dural arteriovenous fistulae (DAVF) at the torcular produce pulsatile tinnitus, intracranial hypertension, and haemorrhage risk. Endovascular embolisation of DAVF at the torcular must preserve the transverse sinuses. Sinus thrombosis at the torcular from hypercoagulable states or infection produces massive intracranial hypertension with rapidly fatal outcome if untreated.
Dural arteriovenous fistula at the torcular Herophili with arterialisation of the transverse sinuses produces pulsatile tinnitus, headache, and intracranial hypertension from retrograde cortical venous drainage; endovascular transarterial and transvenous embolisation combined with surgical disconnection targets the fistula while preserving the transverse sinuses.
