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Occipital Sinus

sinus occipitalis

The occipital sinus is a small and inconstant dural venous sinus running in the attached margin of the falx cerebelli from the confluence of sinuses to the foramen magnum, where it connects with the marginal sinus and the internal vertebral venous plexus. It provides an alternative venous drainage route from the posterior fossa and is the smallest and most posterior of the dural venous sinuses.

Region: Head & Skull

Clinical Relevance

Clinical Notes

The occipital sinus is relevant in posterior fossa and foramen magnum approaches, where unexpected bleeding from this sinus can complicate the approach to the inferior vermis and cervicomedullary junction. It may provide significant venous drainage in cases of transverse or sigmoid sinus occlusion. The marginal sinus at the foramen magnum border, continuous with the occipital sinus, must be protected during suboccipital craniotomy and C1 laminectomy procedures.

Pathology

Common Injuries & Conditions

Occipital Sinus Bleeding in Posterior Fossa Surgery

The occipital sinus and marginal sinus at the foramen magnum rim can be inadvertently entered during suboccipital craniotomy, causing brisk venous bleeding managed by bipolar coagulation and packing, with care to avoid air embolism from the exposed sinus.