Introduction: 

Glomus tumors of the temporal bone are histologically benign, but they can cause severe clinical problems, such as invasion to and destruction of the skull base structures.

Objective: 

We have examined the anatomical background aiding the surgical ablation of C1 type glomus jugulare tumors, especially the landmark stuctures and potential sites of venous blood loss.

Materials and methods: 

Both temporal bones and jugular foramina of 6 dry skulls were investigated, following penetration with a dental drill. We also have dissected 10 blocks from formaline-fixed cadaver heads. The key stuctures of the highest surgical importance were also visualised on these specimen. In 3 formaline-fixed block the vessels were injected with red or blue colored polyurethane.

Results: 

The inferior petrosal sinus has reached the superior bulb of the internal jugular vein beyond the point where it has merged with the venous plexus of the hypoglossal canal. No direct connection was found though.

These sinuses have found to contain other venous plexuses, entering the superior bulb of the internal jugular vein via one or two apertures. A double aperture was noticed only in two cases, in the other eight specimens only a single ostium wasobserved.

The venous plexus of the hypoglossal canal together with the inferior petrosal sinus approach the superior bulb of internal jugular vein between cranial nerves IX and X, either as a duplicated or a single branch.

The condylar emissary vein is connected to the superior bulb of internal jugular vein too. The ostium of this vein has opened proximal from the terminal crista, as it was apparent from the terminal area of the sigmoidal sinus. The distance from the highest point of terminal crista, to the internal aperture of condylar emissary vein was between 1–10 mm with the lumen showing great variability. The largest diameter was found to be 3 mm, but in some cases it appeared so small that its cannulation was hardly possible.

Conclusion: 

The last step in tumor resection is the opening of the superior bulb of internal jugular vein. The origin of an extensive bleeding is likelyto be the condylar emissary vein, which is situated dorsal and rather far from the more ventrally lying cranial nerves. Further quenching if the venous bleeding has to be made between the cranial nerves IX. and X and always, it has to be below the cranial nerve XI., where the venous plexus of the hypoglossal canal and the inferior petrosal sinus are joining the superior bulb of internal jugular vein. The accurate identification of the site is especially important, to avoid excessive blood loss.