**5.1 Pterional approach**

The head is turned away from the side of the craniotomy and the neck should be extended so that malar eminence is at the highest point of the operative field to allow gravity to facilitate brain retraction. The neck should be positioned to avoid excessive compression of jugular veins and the endotracheal tube. Elevation of the head of the bed and ipsilateral shoulder elevation with a pad is used to ensure adequate jugular venous return. The hair is shaved, extending for 3 cm behind the hairline. Skin is incised in a curvilinear fashion from 1 cm anterior to the tragus to the midline. Temporalis muscle is divided by electrocautery and the myocutaneous flap is reflected anteriorly and inferiorly by the subperiosteal dissection with the periosteal elevator and minimal electrocautery, until the root of the zygoma, keyhole, and supraorbital ridge are identified. Posteriorly, the temporalis muscle is retracted for additional temporal exposure.

Adjacent to the Sylvian fissure parts of the frontal and temporal lobes should be widely exposed during the trepanation window formation. The extradural stage includes pterion and lateral orbit drilling. The meningo-orbital band is cut. Dura propria and temporalis are separated from each other. The removal of hyperostotic ACP is impossible without this maneuver. MAC usually involves only temporal dura, thus DP serves as a great orientation layer covering cavernous sinus and protecting its structures during dissection. Intraoperative ultrasound investigation and neuromonitoring should be used during this stage to ensure the ICA and adjacent III and V1 nerves location. Before the intradural stage, it is necessary to visualize the optic nerve in the dural sheath, ICA, and the lateral wall of the cavernous sinus. Arcuate dural incision along the tumoral border allows to use the proximal undamaged dura as brain protection. Incision prolongs to the dura that rostrally covers the optic nerve and then along the upper edge of the cavernous sinus caudally. The edges are connected along the upper part of the cavernous sinus. Mobilized shred is removed together with the adjacent tumor (**Figure 5**).


#### **Table 2.**

*Advantages and disadvantages of pterional and fronto-lateral approaches.*

#### **Figure 5.**

*Final view after tumor removal, right side. 1 – Drilled optic canal 2 – Incised dura around the optic nerve 3 – Optic nerve 4 – Brain tissue 5 – Internal carotid artery 6 – Dural edge 7 – Posterior communicant artery 8 – Oculomotor nerve 9 – Distal dural ring 10 – Superior orbital fissure (connected with optic canal) 11 – Drilled clinoid base; A and B – Preoperative MRI; C – Preoperative CT; D – Preoperative 3D CT bone reconstruction; E – Postoperative 3D CT bone reconstruction.*

At this stage, the ON and supraclinoid segment of the ICA could be visualized. Markedly deprived from the blood supply, the tumor is debulked. Incrementally, the tumor is dissected from ON, chiasm, pituitary stalk, 3rd nerve, bran surface, ICA, PCA, ACA, MCA, and their branches in a sharp manner. Wound hermitization could be conducted with fat or vascularized galeo-aponeurotic flap.

### **5.2 Fronto-lateral supraorbital approach**

The position of the patient is on his back. The head is raised and turned by 30° from the approach side. The skin incision is performed along the edge of hair growth. The musculocutaneous flap is directed toward the superciliary arch. Supraorbitally, a bone flap of approximately 5x3 cm is formed. Avoidance of frontal sinus opening is important and the mucous membrane should be dissected from the bone and sutured by atraumatic sutures if opened. Following the arcuate dural incision, CSF aspiration during Sylvian fissure dissection provides the brain's relaxation and wide working space. There is a tendency to avoid using a retractor for the

frontal lobe. Even if needed, the use should be as the "brain holder" but not for the forced retraction. Tumor dissection is started from the attachment point and after the ICA, 2nd and 3rd nerves visualization the separation from the basal attachment could be safely ended. Following the main arterial supply deprivation, the tumor usually becomes softer and the volume reduction is effectively conducted. This step allows crucial structures to release. The superior and lateral surface of the anterior clinoid bone as well as the optic nerve roof should be skeletonized by excision of the involved dura. The optic canal is opened necessarily and the anterior clinoid process is drilled within its tumor germination. The procedure is ended with the hermetic dural suturing, fixation of the bone flap, and suturing of the skin.
