The transverse sinuses are paired dural venous channels running laterally in the attached margin of the tentorium cerebelli from the confluence of sinuses to the sigmoid sinuses at the petrous-occipital suture. The right transverse sinus is typically dominant and larger, receiving most of the flow from the superior sagittal sinus. Each transverse sinus receives the vein of Labbe (inferior anastomotic vein) from the temporal lobe and communicates with the overlying diploe.
The transverse sinus runs across the inner surface of the occipital bone and is at significant risk during posterior fossa craniotomy and during mastoidectomy surgery where it defines the posterior limit of mastoid air cell removal. Transverse sinus thrombosis may extend from superior sagittal sinus thrombosis or occur in isolation, producing lateral sinus thrombosis historically associated with otitic hydrocephalus from mastoiditis. The vein of Labbe draining into the transverse sinus must be protected during temporal craniotomy approaches.
Extension of mastoiditis infection into the sigmoid and transverse sinuses produces lateral sinus thrombosis with fever, headache, and signs of raised ICP; CT venography confirms the diagnosis and treatment requires mastoidectomy, sinus debridement, and prolonged antibiotic therapy with anticoagulation.
The transverse sinus crossing the posterior cranial fossa marks the superior limit of posterior fossa craniotomy; inadvertent opening of the sinus causes significant haemorrhage requiring immediate sinus packing and repair.
