**4.1 V1-V2 corridor**

sphenoid sinus, maxillary sinus, pterygopalatine fossa (**Figures 1** and **2**) [8].

The gap between the ophthalmic and maxillary nerve is used to reach the sphenoid, maxillary, or ethmoid sinuses. This approach is useful when the tumor extends from the periorbital to the infraorbital and further into the middle fossa, with extension into the SphS, MaxS, and PPF. The relationship of the periorbital area to the sinus trigeminal nerve should be known when increasing the tumor removal rate of benign tumors or when performing extensive resection of malignant tumors. Maxillary nerve is exposed along the nerve up to the MaxS. Delete the lateral orbital wall and leading to the middle cranium, the MaxS is covered by the fatty tissue of the PPF. The pterygopalatine ganglion is hidden in the fat tissue within this PPF and the connection between V2 and the vidian nerve can be seen. Initially, the ZyN branches off from the maxillary nerve and heads in the direction of the zygomatic arch. This ZyN is then transected, allowing the PPF to be detached from the orbit. The PPF will be able to deploy V2 backward along with PPG and palatine nerve and vidian nerve.

A large area can be developed between V1-V2. In addition, a small bony ridge at the corner of V1-V2, the Maxillary strut, can be removed just below and anterior to the sphenoid sinus. The infraorbital nerve can be traced peripherally to enter the maxillary sinus. A sphenopalatine artery runs between the sphenoid sinus and the

#### **Figure 1.**

*Schematic images of V1-V2 corridor. A. the V1 and V2 are exposed after removing the bone of the anterior inferior temporal fossa. The PPF, which is included V2 and pterygopalatine ganglion, can be translocated posteriorly. The incision line is shown on the schema. B. after removing the maxillary strut, the sphenoid, ethmoid, and maxillary sinus are opened between the maxillary orbit and pterygopalatine fossa. EthS; ethmoid sinus, FO; foramen ovale, FR; foramen rotundum, ICA; internal carotid artery, ION; inferior orbital nerve, GG: Gasserian ganglion, MaxS; maxillary sinus, PPF: Pterygopalatine fossa, SOF; superior orbital fissure, SPA; sphenopalatine nerve, SphS: Sphenoid sinus, SupAN; superior alveolar nerve, V1; ophthalmic nerve, V2: Maxillary nerve, ZyN; zygomatic nerve.*

*Surgical Approach to the Cavernous Sinus and Middle Cranial, Pterygoid Fossa DOI: http://dx.doi.org/10.5772/intechopen.104956*

#### **Figure 2.**

*Stepwise dissections of the anteromedial middle fossa triangle. A. after frontotemporal craniotomy, the middle fossa is exposed with elevation of the dura propria from the cavernous sinus lateral wall. The trigeminal nerve, trochlear nerve, and oculomotor nerve are exposed. B. the lateral orbital wall and orbital roof are removed, and the foramen rotundum is unroofed toward the pterygopalatine fossa. The periorbita and pterygopalatine fossa are exposed. C. an incision is made between the pterygopalatine fossa and orbit. D. the pterygopalatine fossa is translocated posteriorly and the zygomatic nerve is bridged between the pterygopalatine fossa and orbit. E. the bone around the maxillary strut is drilled to get access into the sphenoid sinus. The posterior wall of the maxillary sinus is opened between the maxillary and ophthalmic nerves. F. the maxillary, ethmoid, and sphenoid sinus can be opened through the maxillary and ophthalmic nerves. EthS; ethmoid sinus, FO; foramen ovale, FR; foramen rotundum, ICA; internal carotid artery, ION; inferior orbital nerve, GG: Gasserian ganglion, MaxS; maxillary sinus, PPF: Pterygopalatine fossa, SOF; superior orbital fissure, SPA; sphenopalatine nerve, SphS: Sphenoid sinus, V1; ophthalmic nerve, V2: Maxillary nerve, ZyN; zygomatic nerve.*

maxillary sinus, and the exit of the sphenopalatine foramen is visible. This approach is useful for the removal of tumors extending from the anterior middle fossa to the orbital wall, along the trigeminal nerve, or into the maxillary sinus.

#### **4.2 V2-V3 vidian corridor**


The lateral wall of the SOF is exposed, and the lateral orbital wall is removed anteriorly exposing the periorbita. The temporal fossa floor lateral and anterior

#### **Figure 3.**

*Schema of the V2-V3 corridor. A. the sphenoid sinus is opened through the vidian corridor. The vidian nerve runs between the V2 and V3, parallel with V2. The sphenoid sinus is opened medially to the vidian nerve. B. the maxillary sinus and sphenoid sinus are opened in the infratemporal fossa with translocation of the fat tissue of the pterygopalatine fossa. The maxillary and sphenoid sinus are opened through the V2-V3 vidian corridor with a lateral corridor of the V2. The blue arrows show the direction of the sinus. C, D, E. the root of pterygoid is drilled and the vidian nerve is exposed completely. The sphenoid sinus can be opened medial to the vidian nerve. Between the vidian nerve and V2, a small corridor can be opened and used to access corridor to the sphenoid sinus. The vidian corridor can be enlarged with retraction of V2 and vidian nerve. EP; epipharynx, EthS; ethmoid sinus, FO; foramen ovale, FR; foramen rotundum, ICA; internal carotid artery, ION; inferior orbital nerve, GG: Gasserian ganglion, MaxS; maxillary sinus, MM; Muller muscle, PPF: Pterygopalatine fossa, SOF; superior orbital fissure, SPA; sphenopalatine nerve, SphS: Sphenoid sinus, V1; ophthalmic nerve, V2: Maxillary nerve, ZyN; zygomatic nerve.*

to FO and FR is drilled until the periosteum of the exocranial surface of the bone is reached. The FR is unroofed, and the pterygopalatine fossa is exposed as well as the fascia of the temporalis muscle and lateral pterygoid muscle (LPM). Further elevation of the periosteum of the exocranial surface of the temporal fossa floor can reveal the lateral aspect of the pterygoid process.

Drilling of the antero-superior aspect of the infratemporal fossa, between the LPM and temporal dura mater and lateral orbital wall was done in order to gain additional working space in the pterygoid fossa.

Limits of the pterygoid drilling required are the epipharynx inferiorly, the clivus posteroinferiorly, the posterior wall of the MaxS anteriorly, and the posterior part of the lateral wall of the SphS medially.

Access to the SphS is gained through the V2-V3 vidian corridor, which is in the depth of the FLT and limited superiorly by V2, posteriorly by V3, inferiorly by the superior wall of the pharynx, and anteriorly by the pterygopalatine ganglion (PPG). Following the VN anteriorly, the PPG is identified in the PPF along with the sphenopalatine artery (SPA), which is a branch of the internal maxillary artery (IMA). In some cases, lateral pneumatization of the SphS is extensive and the VN is dehiscent in the SphS. Below V2, the PPF can be opened, and the fat of the PPF removed. This exposes the PPG, SPA, and the posterior wall of the MaxS, which is located between the PPG and the inferior wall of the orbit. Anterior to the PPG and below the orbit, the MaxS can be accessed through this V2-V3 vidian corridor below V2.

The posterior wall of the MaxS is thin and can be opened easily, granting access to a large space to insert the endoscope. At this point, endoscopic assistance is required to provide additional illumination and widen the exposure of the SphS and MaxS.

*Surgical Approach to the Cavernous Sinus and Middle Cranial, Pterygoid Fossa DOI: http://dx.doi.org/10.5772/intechopen.104956*

## **4.3 Combined V2-V3 corridor and anterior petrosal approach with endoscopic assistance**


The posterior border of the temporal muscle was incised and detached from the temporal bone. The temporal muscle is retracted anteriorly and exposed to the posterior point of the root of zygoma. The temporal craniotomy was performed and access to the middle fossa extradullary.

Initially, the MMA is traced to confirm the foramen spinosum (FS), and the dura mater is thoroughly dissected anteriorly and posteriorly. The arcuate eminence (AE) is identified posteriorly, the GSPN is peeled off posteriorly to expose the pyramidal bone.

The middle meningeal artery (MMA) is coagulated and cut 1 mm out of the FS. The foramen rotundum (FR) is identified anteriorly, where the dura mater enters the bone. An incision is made in the dura above the foramen ovale (FO), and

#### **Figure 4.**

*Schematic representation of the infratemporal fossa, with opening of the vidian corridor and petrous rhomboid. A. the blue arrow shows the direction of access to the upper-mid and lower clivus through the vidian corridor. The green arrow shows the trajectory to the petrous apex and inferior cavernous sinus through the petrous rhomboid. The purple arrow shows the posterior view to the medial jugular foramen and hypoglossal canal through the petrous rhomboid. The light green arrow shows the direction to the clivus. B. the cadaveric view of the middle fossa. The blue arrow shows the direction of access to the upper-mid and lower clivus through the vidian corridor. The purple arrow shows the posterior view of the medial jugular foramen and hypoglossal canal through the petrous rhomboid. The light green arrow shows the direction to the clivus.*

one thin layer of dura (osteal dura) is elevated to lift the dura propria and expose the lateral wall of the cavernous sinus [22–26].

After performing the anterior petrosal approach with post meatal drilling, the petrous rhomboid bounded by the GSPN, superior semicircular canal, petrous ridge, and the posterior border of the mandibular verve, gives a working space to the middle and posterior fossa.

The facial, cochlear, and vestibular nerves have a distance from the dura mater of the internal auditory canal (IAC) from this side. Thus, the dura mater can open if they are not compressed and drained by the tumor.

Then, an anterior petrosectomy with extended petrous bone removal toward the petrous apex and ventral cavernous sinus wall through the petrous rhomboid. The bone around the internal auditory canal (IAC) can be removed completely. Usually, the IPS is a landmark of the inferior limit of the anterior petrosal approach.

When the tumor extends to the clivus and/or condyle, the tumor makes a tumor corridor around the petrous and clivus bone. After crossing the IPS, the clivus cancellous bone can be drilled and arrive at the medial aspect of the jugular bulb. A partial clivectomy could be performed by removing bone around the JF.
