Cavernous sinus

Dissection by Pierre-Hugues Roche
Dissection by Oliver Bozinov

The surgical indications for entering in the cavernous sinus are very limited. However, there are techniques, for exposure of the lesions around the cavernous sinus.

In the following images the cavernous sinus is approached after right-sided orbitozygomatic craniotomy. Two techniques are presented – approach from the superior orbital fissure and from middle cranial fossa. 
The middle fossa floor anatomy and anterior petrosectomy technique after OZ approach is presented additionaly.

Fig. 1. Exposure after right orbitozygomatic craniotomy. The bone over superior orbital fissure (SOF) is drilled away. The anterior clinoid process (ACP) is removed. The exposure to the cavernous sinus from SOF is commenced by cutting the periosteal dural bridge.

Fig. 2. After dividing the periosteal dural bridge the dissection is continued to the superior orbital fissure and the elevation of the dura propria is performed by combination of sharp and blunt dissection.

Fig. 3. Elevation of dura propria from the lateral wall of the cavernous sinus.

Fig. 4. Final view; SOF (superior orbital fissure)

Fig. 5. Opening of the superior orbital fissure and the cavernous sinus

Fig. 6. The intracavernous ICA is seen. V1 nerve elevated with microdissector and shows the VI nerve. Ophthalmic division of V nerve courses in the wall of the cavernous sinus. VI nerve is within the cavernous sinus, deeper to V1 and close to the ICA. The Gruber’s ligament above the Dorello’s canal, where the VI nerve passes is also identified.

Fig. 7. Final view of the structures within the cavernous sinus.

Fig. 8. Final view of the neurovascular structures within the cavernous sinus after microsurgical dissection.

Fig. 9. After that the dissection is continued with unroofing the foramen rotundum around V2.

Fig. 10. The elevation of dura propria from the lateral wall of the cavernous sinus is done by cutting the periosteal dural bridge on V2 after previously unroofing the foramen rotundum.

Fig. 12. Cutting the middle meningeal artery should be done carefully, not too low on its intracranial entrance of the foramen spinosum, where branches to the facial nerve could exit.

Fig. 13. Elevation of the dura from the middle cranial fossa should be done in “back to front manner” because by this is safest for the greater superficial petrosal nerve (GSPN). Other landmarks in the middle cranial fossa are identified too: V3, arcuate eminence.

Fig. 14. Drilling of the middle fossa is begun in the petrous apex and the boundaries of the approach defined by Kawase: GSPN, arcuate eminence, petrous ridge, V3.

Fig. 15. View after drilling the petrous apex. ICA petrous segment is exposed.

Fig. 16. Glasscock’s triangle boundaries: GSPN, V3, and a line connecting the foramen spinosum to arcuate eminence. It contains the petrous portion of the ICA.

Fig. 17. Kawase’s approach boundaries: GSPN, arcuate eminence, petrous ridge, V3. The inferior border of petrous apex drilling is limited to the inferior petrosal sinus. The dura of the posterior fossa is identified. The IAC (internal acoustic canal) is unroofed.