[Infection transfer between the maxillary sinus and endocranium]

Rhinogenous brain abscesses usually originate from a frontal sinusitis, rarely from the ethmoidal system or the maxillary sinus. However, there are different pathways that can lead to the transfer of a maxillary infection to the endocranial compartment.

A patient with frontal brain abscesses originating from a maxillary sinus infection is presented and diagnostic steps, therapy as well as pathophysiology are discussed.

The venous plexus of the maxillary sinus drains through the posterior wall of the antrum of Highmore into the deep facial vein that leads into the pterygoid plexus and then through the rete foraminis ovalis into the cavernous sinus. In addition, numerous small veins perforate the osseous roof of the maxillary sinus and enter the orbit joining the superior or inferior ophthalmic vein. They are also connected to the cavernous sinus or the pterygoid plexus. A number of veins perforate the anterior wall of the maxillary sinus communicating with the angular vein that drains into the superior ophthalmic vein and into the cavernous sinus. From the cavernous sinus, the blood arrives at the deep middle cerebral vein that usually communicates through the white substance towards the brain's superficial venous system.

The presence of these maxillo-cerebral venous anastomoses explains the spread of infection from the maxillary sinus to the white substance of the brain without any direct association with the base of the skull.